2900-116-R Memorandum of Project MICHIGAN SPIN RESONANCE of V2+, V3+, V4+ in 0-AI203 JOHN LAMBE CHIHIRO KIKUCHI November 1959 SOLID-STATE PHYSICS LABORATORY THE UNIVERSITY OF MICHIGAN Ann Arbor, Michigan

DISTRIBUTION OF REPORTS Distribution control of Project MICHIGAN Reports has been delegated by the U. S. Army Signal Corps to: Commanding Officer U. S. Army Liaison Group Project MICHIGAN Willow Run Laboratories Ypsilanti, Michigan It is requested that information or inquiry concerning distribution of reports be addressed accordingly. The work reported herein was carried on by the Willow Run Laboratories for the U. S. Army Signal Corps under Project MICHIGAN, Contract No. DA-36-039 SC-78801, and for the Air Force Office of Scientific Research under Contract No. AF49(638)-68. University contract administration is provided to the Willow Run Laboratories through The University of Michigan Research Institute.

WILLOW RUN LABORATO R I ES TECHNICAL MEMORANDUM 2900- 116-R PREFACE Documents issued in this series of Technical Memorandums are published by Willow Run Laboratories in order to disseminate scientific and engineering information as speedily and as widely as possible. The work reported may be incomplete, but it is considered to be useful, interesting, or suggestive enough to warrant this early publication. Any conclusions are tentative, of course. Also included in this series will be reports of work in progress which will later be combined with other materials to form a more comprehensive contribution in the field. A primary reason for publishing any paper in this series is to invite technical and professional comments and suggestions. All correspondence should be addressed to the Technical Director of Project MICHIGAN. Project MICHIGAN, which engages in research and development for the U. S. Army Combat Surveillance Agency of the U. S. Army Signal Corps, is carried on by the Willow Run Laboratories as part of The University of Michigan's service to various government agencies and to industrial organiz ations. The work reported herein was jointly sponsored by the U. S. Army Signal Corps and the Air Force Office of Scientific Research. Robert L. Hess Technical Director Project MICHIGAN iii

WILLOW RUN LABORATORIES TECH N ICAL MEMORANDUM 2616- 12-R/2900- 116-R ABSTRACT Divalent vanadium has properties similar to those of trivalent chromium in sapphire, which has wide application in masers. The electron-spin resonance absorption properties of vanadium sapphire are reported here. It is shown that vanadium normally is predominantly trivalent, with a small amount being in the tetravalent state. By x- or gamma-irradiation, vanadium is converted to the divalent state. The hyperfine-structure component separ2+ 3+ 4+ ation for V, V, and V are about 88, 110, and 140 gauss, respectively. Because of its readily recognizable spin-resonance signature due to its nuclear spin, and because of the ease of producing different oxidation states, it is suggested that vanadium may be a suitable probe with which to study ionization effects in certain solids. 1 INTRODUCTION The purpose of this memorandum is to present some of the spin-resonance properties of various oxidation states of vanadium which were reported earlier (Ref. 1 and 2) and to complement the optical measurements of vanadium sapphire reported by Low (Ref. 3) and by Pryce and Runciman (Ref. 4). Experiments were designed to provide further information concerning the nature of impurities in corundum in various oxidation states. The need for this further information became apparent following extensive preliminary investigation of maser action in ruby (Ref. 5). The initial measurements on the spin-resonance properties of ruby were reported by Manenkov and Prokhorov (Ref. 6), by Zaripov and Schamonin (Ref. 7), and by Geusic (Ref. 8), and more detailed studies have been made by Schulz-DuBois (Ref. 9). The temperature dependence of the zero-field splitting was made by Cross and Terhune (Ref. 10). But these It is a pleasure to acknowledge the technical assistance of R. Ager and J. Baker, who carried out many of the measurements during the progress of the present investigations. 1

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM 2616-12-R/2900-1 16-R measurements merely indicate that some, if not all, of the chromium in corundum is in the form of Cr and that the crystalline electric field about this ion has axial symmetry; these measurements do not reveal to what extent the chromium is present in other oxidation states, and, furthermore, do not show the degree of pairing and clustering. An attempt to obtain this information directly by means of spin-resonance measurements has met with difficulties because chromium does not have an easily recognizable signature. Natural chromium consists largely of the isotope of masses 50, 52, 54, but only 9. 5% of the odd isotope Cr-53. Rubies containing Cr-53 can be prepared, but the hyperfine structure (hfs) is comparable to the line width; furthermore, nothing is known about the effect of the oxidation state upon the hfs. Consequently, it appeared that a better approach would be to bracket the properties of chromium in corundum by substituting other paramagnetic ions in the lattice. The suitable candidates with well-recognizable signatures are vanadium (V-51, I = 7/2, 99. 75%) and manganese (Mn-55, I = 5/2, 100%), flanking chromium to the left and right, respectively, in the periodic table. Molybdenum consisting of Mo-95 (I = 5/2, 15. 7%) and Mo-97 (I = 5/2, 9. 5%) offers another possibility. This element occurs directly beneath chromium in the periodic table, and spin-resonance studies in the paramagnetic salts have shown that it behaves somewhat like Cr (Ref. 11). When vanadium sapphire is grown from a mixture of Al203 and V205 powder, spin-resonance measurements show that vanadium is 4+ predominantly trivalent with a small concentration of V. If this sample is subjected to ionizing radiation, some of the vanadium is converted to V. Also, an interesting result is the monotonic increase of the hfs coupling constant with increasing degree of ionization. There is a similar effect in atomic hfs, but the resemblance appears to be only superficial (Ref. 12 and 13). Recently, J. Wertz and his collaborators (Ref. 14) have made a systematic study of the spin-resonance properties of various iron-group elements in MgO. It should be noted, however, that a-A203 has an advantage in that the various oxidation states of vanadium can be distin4+ 3+ 2+ guished unambiguously. The reason for this is that the spin of the states V, V, and V are 1/2, 1, and 3/2, respectively; and in a crystalline field of trigonal symmetry, each spin state can be distinguished from the others by the number and the angular dependence of the fine-structure groups. Since the crystalline field in MgO is cubic, no fine-structure splitting is produced; thus each of the three valence states is expected to give a single group of 8 isotropic, or almost isotropic, hfs lines. The three vanadium oxidation states can then be distinguished only by the differences, if any, of the hfs coupling constant. 2

WILLOW RUN LABORATORIES TECH N ICAL MEMORANDUM 2616-12-R/2900-116-R 2 EXPERIMENTAL METHODS Measurements were made with X- and K-band magnetic resonance spectrometers. The ++ latter was used for V measurements in order to avoid some of the complications arising at X-band frequencies. Most of the measurements, however, were carried out at 9400 mc/sec. The X-band cavity was made of coated ceramic so that 5-kc/sec magnetic-field modulation could be used (Ref. 15). The vanadium sapphire was irradiated either in the Co-60 gamma-ray source or by means of 50-kv x-rays. For x-ray irradiation at liquid-nitrogen temperature, a styrofoam boat containing liquid nitrogen and the sample was placed adjacent to the exit port of the x-ray machine. With this arrangement it was possible to transfer the sample into the magnetic-resonance spectrometer without any appriciable warm-up. 2+ The measurements of T1 of V at liquid-helium temperature were made by comparing 3+ 3+ saturation of this resonance to that of trace impurities of Cr. The T of Cr, according to our earlier measurements, is known to be about 50 msec at 4.20K. 3 EXPERIMENTAL RESULTS 3+ 3.1. V 3+ The spin resonance of V was observed in a-A203 grown from a powder mixture of 2 3 Al203 and 0.1% V205 prepared by The Linde Company. The results presented here are essentially the same as those of Zverev and Prokhorov (Ref. 16), but some points should be noted. These workers reported following the spectrum up to an angle of about 600 between the c-axis and the magnetic field. Our measurements were made to 800. For larger angles the spectrum fell beyond the magnetic-field range of the Varian 12-in. magnet with 5 1/4-in. gap. Figure 1 shows the spectra for 00, for which the hfs components, about 20 gauss wide, are 110 gauss -4 -1 apart, giving A = 1.02 x 10 cm. As the angle is increased, the center of the spectrum shifts to higher fields and the separation between the components increases. As expected, the signal showed no sign of saturation up to power of 50 mw. No signal was observed at 770K and 3000K. It was found that maximum absorption is obtained when the sample was placed in the cavity so that the rf field is parallel to the static magnetic field. This indicates that the transition under study is one for which AM = 2. 3

WI LLOW RUN LABO RATO R I ES TEC H N I CAL MEMO RA N D UM 2616-12-R/ 2900-1 16-R V3+0= 0o 1440 gauss 1414- T=4.20K 2240 gauss 3+ FIG. 1. SPECTRUM OF V IN a-A1203 AT 4.2K FOR 0 = 00 3+ The spin-Hamiltonian applicable to V is given by = g,1 OH S + g(HS + H S ) + DS 2+ E(S - S ) + AI S + B(I S + IS ). (1) 1z z x yx y z x y z z xx yy The rhombic-field coefficient E causes the mixing of S = ~1 states, resulting in the observed -l1 transitions. Since these levels are about 10 cmr above the S = 0 level, the effective Hamiltonian can be written as:- = gll H S + AS I, (2) obtained by deleting from Eq. (1) those terms that give only off-diagonal elements and also by omitting the axial field term DS, which is the same for both S = ~1. From Eq. (2) it follows z z immediately that hu = gll OH cos 0 + 2 Am, so that the position of the m-th hfs component is given by Hm = 2 + Am) /(gl] cos 0). (3) -1 The center of the spectrum then should vary as (cos 0), as shown in Fig. 2. A more detailed calculation (Appehdix A) gives l sin +B2[ I(I + 1) - 2] hv = (gllH cos 0 + Am) - 2 D 4

WI LLOW RU N LABORATORIES TECH N ICAL MEMORANDUM 2616-12-R/2900-116-R +E A } HE sin Bm g E 2 D cos 0 D 2 2 2 (gllOH cos 0 + Am) J 4gl o H cos 0 Another characteristic seen from l0 l lFig. 1 is the equal-spacing hfs components. This is in contrast to the appre8000 ciable deviation from equal spacing for 2+ the V hfs. The reason for the equal 3+ ~~7000 |_~ l_ l~~ Lspacing of the V hfs lines sters from 7000 V3+T=4.2OK the fact that the levels S = ~1 are not Position of Center of I connected to each other by the term Hyperfine Group H e G p B(I S + I S ). This term does connect 6000 = Experiment I x y y = perim e T the S = ~l levels with S = 0, but the - = Approximate Theory z -1 z ^ T |. fn=Ho\cH- 1 l i /latter is about 10 cm away. m^ H:^H=Ho(0~") X cos Q M 5000 { 3.2. V X2^~~~~ Il^~~~~~~ IIn examining the spin resonance of our crystals at 3000K, a group of lines 4000 / were noted in the region of g 2. Closer study revealed that there are 8 such lines separated by 140 gauss and that the center B3~'000 of the group remained in the same position as the angle between the c-axis and the /^^^5~) ~ static magnetic field was varied. At 2000 0_ C = 900, a fairly clean spectrum is obtained, as shown in Fig. 3. The strong 0 15 30 45 60 75 90 0 line is due to a trace impurity of iron, FIG. 2. ANGULAR DEPENDENCE OF which is usually found in sapphire. The POSITION O CENTER OF HFS FOR spectrum at 0 = is complicated by the V3 AT 4.20K 3~ presence of a trace of Cr The spectrum of 8 lines is found in materials as received. The absorption strength is not increased by x-irradiation. The concentration was estimated to be about 10 /cm. Observations suggest that both the g-value and the hfs constant are isotropic, having the values 5

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM 2616-12-R/2900-116-R -4 -1 gll = g1- 1.97 and A =B = 1.32 x 10 cm The fact that only one isotropic group of 8 lines is detected suggests that the spectrum is due to tetravalent vanadium. Furthermore, this assignment is consistent with the suggestion 4+ by McConnell, Porterfield, and Robertson (Ref. 17) that the hfs constant A for V is greater 2+ than that of V. V4+O=90o T=300~K 2980 gauss 4000 gauss FIG. 3. SPECTRUM OF V4+ IN ra-A123O AT ROOM TEMPERATURE FOR 0 = 900 6

WI L LOW R UN LABO RATO R I ES TEC H NICA L MEMORANDUM 2616-12-R/2900-116-R 3.3. V2+ 2+ The V spectrum was the first of vanadium sapphire detected in our laboratory. Brief comments have been made on two earlier occasions (Ref. 1 and 11). Upon gamma- or xirradiation at room temperature, a spectrum consisting of three groups of 8 lines is produced. The presence of three groups shows that the electron spin of the paramagnetic center is 3/2. 2+ 3+ Consequently, the spectrum is due to V, which is isoelectronic with Cr. The spectrum was examined at both X- and K-band frequencies. Figures 4 and 5 show the typical spectra obtained at X-band frequencies for 0 = 00. The spectrum is complex near the magnetic field of about 3300 gauss (Fig. 4) because the levels S = 1/2 and 3/2 cross each other and the states z become scrambled through the hyperfine interaction. At higher fields, the two levels become well separated so that the admixing decreases, resulting in a simple spectrum as shown in Fig. 5. V2+; 0=0o T =3000K 0 11 11 0 Co CD (M If I CO FIG. 4. SPECTRUM FOR V2+ IN a-A203 AT 3000K FOR 0 = 00 NEAR S = 1/2 AND 3/2 CROSSOVER z 7

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM 2616-12-R/ 2900- 16-R 6600 gauss -88- 7224 gauss v 2+I 00 T =300K FIG. 5. SPECTRUM FOR V2+ AT 3000K FOR 0 = 00 WELL ABOVE THE CROSSOVER POINT The spin- Hamiltonian is given by = g3S -H - D (S -) +AI.S, (4) in which it is assumed that g and A are isotropic and that the sign of D is negative, as in 3~ Cr. If the magnetic field is along the c-axis ( = 00), the energy-level diagram consists of four groups of 8 lines, depicted in Fig. 6. The energy-level diagram is simple, except in the region of H O and 2D/g3, the latter being marked by a circle. Figure 7 shows the details of the crisscrossing of energy levels in this region; Fig. 8 gives the behavior of the wave functions and the energy levels of a pair of perturbing levels. The unperturbed electron and nuclear spin functions are represented by m and Xm, respectively, and X and m are defined by m m m m X = A I(I + 1)- m(m- 1), (5) m 2 and g11 3LAH m 2X m in which AH is measured from the point where the levels would cross were it not for the m perturbing action of the hyperfine interaction. Furthermore, 8

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM 2616- 12-R/2900-1 16-R 2 2 (1 + + m - ) 1 N and + +Vl+ 2 m m (6) N = - - ^ ~. H FIG. 6. ENERGY LEVEL DIAGRAM OF V2+ FOR 0 = 00 9

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM 2616-12-R/2900- 116-R M = 3/2 FIG. 7. DETAILS OF ENERGY LEVEL CRISSCROSSING NEAR CROSSOVER POINT The effect of this admixing of wave functions at the crossover point is to produce a spectrum consisting of more than 8 lines predicted by a simple theory. The theoretically expected spectra for three different resonance frequencies are shown in Fig. 9. Note that the spectrum becomes progressively simpler as the resonance frequency is moved away from 2D + 3/2A. As indicated already, the spectrum is also complex near zero magnetic field, because of the near-degeneracy of the S = ~1/2 states. It should be noted, however, that the z energy levels are simple where the levels S = -1/2 and 3/2 cross over (H- D/gS), if both z the crystalline field and hyperfine interaction have axial symmetry. If such is not the case, the spectrum should again be complex. For this reason, a study of the region should reveal small deviations from the spin-Hamiltonian given by Eq. (4). This can be done by examining the transition -3/2-> -1/2 with resonance frequency hv - gjH + 2D 3D = 14, 200 me/sec, 10

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM 2616- 12-R/ 2900- 116-R -8 /- 4 2 // 2 4 6/ 8 /// I / // / I / E+=2D+3/4A + Hm(m+Vl1+-m2) // /- 4 6/ 8 / / / -i / / //'___ =(-A+3 /4 gl FIG. 8. ENERGY AND WAVE FUNCTIONS OF PERTURBING STATES 11 H (OL<2 A/+/4A/ FIG. 8. ENERGY AND WAVE FUNCTIONS OF PERTURBING STATES~~~~~~~~~~~~~~~ 11~~~

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM 2616- 12-R/2900- 116-R or the transition (see Appendix B). hv -~ gjH = 4700 me/sec. ITT T hTT F TT_ hf =2D + 3/2A TT T T T IT T T I TIT T 2D+3/2A+5A r T1 1~ T T T T T T =2D+3/2A+IOA FIG. 9. CALCULATED SPECTRUM FOR DIFFERENT RESONANCE FREQUENCIES Some details of the x-ray process were noted. It was seen that the x-ray production of 2+ 2+ V saturated quite rapidly. After about 3 hr of irradiation, no significant increase of V was observed. There was a slight relaxation of the V concentration immediately after x-irradiation, but thereafter the concentration remained essentially constant at 3000K. The V ions, however, can be bleached by heating to 7000C. X-irradiation did not appear to produce any new 3+ 3+ spin-resonance centers. Furthermore, the lines of Cr and Fe were not affected by the x-rays. Vanadium sapphire crystals were also irradiated and measured at 770K. It was 2+ found that V ions are produced, but the effects are similar to those of room-temperature irradiation. 2+ 4+ It is of interest to note that the observed hyperfine splitting going from V to V increases 4+ as might be expected on the basis of the charge mismatch with the lattice. The V should tend 2 + 3+ to pull in the electron charge cloud more strongly than V. V is then roughly in between. The hfs coupling constants are a measure of the electron charge density at the V-51 nucleus. 12

WILLOW RUN LABORATO R I ES TEC H N I C AL MEMORANDUM 2616- 12-R/2900-116-R 4 IRRADIATION PROCESS 2+ The production of V by means of x-rays is of special interest in the study of electrontransfer processes in sapphire. The process that suggests itself immediately is V ++ hv (x-ray) —>V + V+ This process is ruled out, however, because there is no apparent increase in the V signal 2+ 4+ upon irradiation and because the final V signal is much larger than the V signal. Further3+ 3+ more, the reasonance absorption signals of the trace impurities, Cr and Fe, were carefully examined, but no observable effects due to x-rays were detected. This suggests that some unknown center in the sapphire can yield an electron which can be trapped at V3+ to give 2+ 2+ V. Since a fairly high concentration of V is produced (about 0.01%), a substantial number of of the electron-donor defects are likewise produced; these centers do not appear to show spin resonance. It has been noted that the addition of Cr3+ and V3 to sapphire increases the sensitivity to 3+ x-ray coloration (Ref. 18). In the case of V, it may be that, by trapping out electrons, the V tends to stabilize a color center which would then be a trapped hole. As yet, however, no definite statement can be made as to the nature of the electron donor. 5 DISCUSSION In contrast to those for manganese, which has been studied in a variety of host materials, liquid or solid (Ref. 19 and 20), the spin-resonance investigations of vanadium have been limited thus far to only a few materials. A list of some of the materials is given in Table I. It would be of interest to investigate the properties of vanadium in other materials such as ZnS, ZnO, CdS, etc., single crystals or powders. The advantage of using vanadium over manganese is that the latter appears to be always divalent, whereas with vanadium, the oxidation state can be readily altered by ionizing radiation. During the course of this investigation, it appeared that it might be possible to obtain information about the nature of atomic displacements produced by nuclear radiation by examining the spin-resonance spectrum of ruby near the first crossover, occurring near 2000 gauss. If lattice vacancies produced by nuclear radiations become associated with the chromium ions, the crystalline electric field will no longer have axial symmetry, so that the appropriate 13

WILLOW RUN LABORATORIES T E C H N I C AL MEMORANDUM 2616-12-R/2900-116-R spin-Hamiltonian will contain a rhombic-field term. This will have the effect of admixing the states S = -1/2 and 3/2. This particular region of the energy level diagrams can be exz plored with frequencies near 5.75 kmc/sec and/or 17.25 kmc/sec. The advantage of using chromium rather than vanadium is that the results will not be complicated by hyperfine interactions. TABLE I. HYPERFINE STRUCTURE FOR VANADIUM IN VARIOUS MATERIALS 4 -1 Material Valence A x 10 cm State Ref. V(NH )2 (S0)2 6H20 V 88 Crystal 21, 22 4 2 (SO 4)2 2 K4V(CH) 3H2 V -56 Crystal 23 V(C H ) V 26 Benzene solution 17 5 5 2 ++ VO(CH 5)2 V 71 Benzene solution 17 VOSO4 V 114 Solution 24, 25 Vanadium (IV)-Cupferron Chelate V --- Solution 26 ++ MgO: V V 76 Single crystal 14, 27 Chelate VanadylacetylAcetone V 107 Solution 28 Vanadyl Eteoporphyrin I V 52 Benzene solution 29, 30 (B = 159) 14

WILLOW RUN LABORATORIES TECH N ICAL MEMORANDUM 2616- 12-R/2900-116-R APPENDIX A 3+ Crystalline Field Calculations for V 3+ 23 The ground state of V is (3d) F3. In a cubic field, the orbital septuplet is split into an upper singlet and two triplets. The lowest triplet is split further by a trigonal field into a lower singlet and an upper doublet. When the spin is taken into account, with S = 1, the triplet becomes a ninefold level, which under the combined action of the trigonal field and the spinorbit coupling is split with a singlet (M = 0) lying lowest then, fairly close, a doublet (M = ~1l), and the remaining levels some hundreds of wave numbers higher. The magnetic susceptibility measurements indicate that the separation of the singlet and the doublet is of the order of 5 cm (Fig. 10)., ~ ^ - r. (1) rS 3FF 3F3 (2) \ (3)2 Cubic (1) Axial XL.S FIG. 10. CRYSTALLINE ELECTRIC FIELD SPLITTING OF THE GROUND STATE OF V3+ 3+ The Hamiltonian for the V ion is given by = S S. g. H +D 2 + +SAIS S +I S+) (7) 3 2 + - z z 2 in which D and E are the axial and rhombic crystalline field lines, and A and B the parallel and perpendicular hfs coupling constants. 15

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM 2616-12-R/2900-116-R Consider first the case in which the nuclear effects are neglected. The matrix elements of the Hamiltonian' = 3SgH +D S + + S (8) are <MIl1' IM> = fglH M + D(M2 ) <M + 141 M> = -g g1H /2 - M(M + 1) <M - lI'IlM> =-g1H+ V2- M (M - 1) (9) <M + 21' IM> =-E V[ 2 - M(M + 1)] [2 - (M + 1)(M + 2)] 2 <M - 21 4' M> = - [ 2 - M(M - 1)] [2 - (M - 1)(M - 2)]. This gives rise to the matrix M =-1 0 1 -g1 Hz +D 1 -X V -2+ I ^g^H_ " ---? 2 - 1 OH g3 OjO O |g-L - H- V 3I 3H+ (10) -X D g1 g11 PH +1 L E |J2 g j |H_ This leads to the characteristic equation 12 \( \2 2\2 2 2 -(D + X 3D -X + +D gl1 f Hz 2 g 2H (D t ) E 2 2(H 2 + H) 0. (11) 16

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM 2616- 12-R/2900- 116-R If the magnetic field is along the z-axis, H = H = 0, H = H, and the roots of Eq. (11) are + - z 2 X =3 and 1 2 222 X =-7D E gll 3 H (12) The associated wave functions are 2 X = —D: o =o 3 o o + 1 1/ 2 1 X = -D V 2g1 H -(c + c + 3 N2 -l 11 with - gll OH + E + 2 g13 H E g z "1 N' 2 N and 2 2 222 2 222 N =2E +2g(_ HH + 2g 3H E + gll 3 H These functions can be used to obtain the approximate angular dependence of the eigenvalues, and hence of the absorption spectrum. The Hamiltonian of Eq. (8) can be written in the form (0)+4 (14) with j0) = glIIS H + D 2 2+) (+2 S) and g-L3(H S +HS).:- - + + - The Hamiltonian (0 is diagonal in the wave functions of Eq. (13). f/ be taken as the perturbation Hamiltonian, its matrix elements with respect to the wave functions of Eq. (13) are 17

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM 2616- 12-R/2900-116-R gl. <01'>" j(+> H + c H )V 2N 1H- 2+ aind (15) gil <ol l'" [-> (- c H H) /, 2N 2- 1 + so that E+ 1 2 ^ 2~22~ 22 2 (CH + c2H )(c H + c H) 2 9- + 1 + 2 X (0):-D + + gll H + 2N2 1 2 (16) 2N D+/E2+ g11H and - 1 2)~ —-— 3~5~; 21 2f2 j-c2 H.. + c1H 2 2 20- +gc1iH+ X (0) =-3D - E + gll 13 H + (17) 3 I z 2 2 2 2 ( D- /E+gl H Therefore, hv =k (0) - X(0) 2 2 22 22 f2 2 2 2 22 g- 3 H H E + gll 3 HZ g_ /2 ~2 z-2-T 2 2 2 22 2 2 2 2 22 2 D - E - g 3H N D - E - gllj H 22 2 2 2 2 g2 ~_ +g, / H g_2/2 C 2 2 2 2 2 z 2 2 2 - 2 2 E H - H H +,+H (18) D NH 2 N D if gll3H >> E. Assume E small. I+ E + D E +' = + O H X+(0) = + 3H + E, 2gH -131 2gllH II z II z (19) -E D E2 -1 - 2g ljH z 1 X(0) =-3 - g13H - EH The above expression becomes 18

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM 2616- 12-R/2900-116-R 2 g 2l g 33 2 2 E 2 E sin 0 hv = 2gllH cos 0 + sin s cos 0 + (20) gllH cos D2 gll D cos 0 Return now to the original problem. (0) - gll, 2 2 ES 2 S 2 AIS z z z "3 + - z z (21) B 4-, "=-(H S +H S )+ (I S +IS). 2 -+ 2 + +The wave functions that diagonalize 4() are obtained from the solution of -1 1 - gll3H - Am E -X - + gll3H + Am 3 11 z 1 E The eigenvalues and the corresponding wave functions are + =D + E + (gllH + Am)2 z (22) + 1 N(C l + C24 ) N 1- I 2 1 and -D 2 /2 X 3 /E +(gll3H +Am), z (23)' N(-c 2- 1 11)' 19

WILLOW RUN LABORATO R I ES TECHNICAL MEMORANDUM 2616-12-R/2900-116-R with c E (24) c2 gll3H +Am +E + (gll3H +Am) and 2 2 2 N = c + 2 The off-diagonal elements corresponding to Eq. (15) are now gl1 <0, ml t I + m> (c H + c H ) I2N 1 2 and (25) glP <O, ml4,I -,m>: (-c H + c H+), N 1/ 2 - 1 + and the additional elements are: Bec <0, m+ll^l"I +,m>= YI(I + 1) - m(m + 1) Be <0,m- 1ll"~ +,m>= V-(I+ 1) - m(m - 1) Be <0, m+ll^"I -,m>= 1 I(I + 1)- m(m + 1) Be <0,m -lI/I -,m>= - 1 VI(I + 1) - m(m - 1). N V-2 Therefore, +( D 2~g2 2 IclH + c2H+2 ) +Am)32 22 2 X(O)=-~ E + (gll3H +Am)+ 32z 222 + ~ I(I + 1) - m(m + 1)] ^2N D +YE2 + (g12H + Am) 20z~~~Z 2 20

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM 2616-12-R/2900-116-R 2 2 C + 2 [I(I + 1) - m(m - 1)]. (26) 2N D + (gllE3H +Am) X (0) = — E +(gH + Am)+Ar) + 1H + 2N D-/E + (gll3H + Am) ^ )i z (27) 22 22 B1 I(I + 1) -m(m + 1) 2 1(1 + 1) - m(m - 1) 2N2 - + 2 2 /- 2+(gH +Am) 2N D - + (gll H + Am)2 Consequently, + 2 hv = X (0) - X (0) g2 g2 Dc(E2 + H g2 1 2 + (glH +Am)2 =2 E + (gIH +Am)+ 2 2 2 2 2- 2 2 HH N D - E -(gll3pH +Am) D - E - (gl13H + Am) l /H ) l. +2 2 2 2 B E + (gc H + Am) B ( 1- C 2 1 2 Dm B 1) 3 c-[l m + + AI(I + 1- (28) D - E - (giH +Am) N D -E - (g1H + Am) If gii PHz + Am ~>> E, the above result becomes 222 2 22 2 g1_3DE(H +H H ) g 2(gPHz +Am) E + hv = 2(ggllH + Am)2 + H H - O +^- D Am 2 2+ ~11z2gj0z z B 2(giglH + Am) 2 2 2 [1(+1) m -D (1- ^,). (29) or 2 g1 23HE sin2 0 g1 13 H (g1OHcos 0 +Am) sin 0 hv = 2(g(lOH cos 6 + Am) +~ + 2A gH cos 0 + Am g D cos D 2 9 2 2 9 f(g1PHncos 0+ AAm)[ I(+ 1)-r -Bh2 cos o). (30)m 21

WILLOW RUN LABORATORI ES TEC H NICAL MEMORANDUM 2616- 12-R/2900- 116-R APPENDIX B 2+ Crystalline Field Calculations for V 2+ 3+ 4 The ground state of the V ion, like Cr, is F3/2, and its splitting in a crystalline 3/2 2+ field is as shown in Fig. 11. The spin-Hamiltonian of the V ion is given by 3S - g H - D - ) + AIS + IS + I S), (31) z 4/ zz 2+ -+ with S = 3/2, and I = 7/2. The sign of the crystalline field term, D, was taken to be negative, 3+ as in Cr (B) I! ~r4 F3/2 (3) F5 L~ ^ r2:, Cubic Trigonal XL*S FIG. 11. CRYSTALLINE ELECTRIC FIELD SPLITTING OF THE GROUND STATE OF V2+ Of primary concern here will be the case in which the magnetic field is parallel to the c-axis. The Zeeman term then becomes glnSZ H. so that the matrix elements are given by: 22

WILLOW RUN LABORATORI ES TECHNICAL MEMORANDUM 2616-12-R/2900-116-R 3 3 3 3 <~ ml r>= ~-2gll H - D ~-2Am 1 1 1 <~2 ml +I~7 m>= ~gl13H + D ~-Am 1 l3 <2,m+ltll m>= - B I(I + 1) - m(m + 1) (32) 2 2 I/T <- 2m+-il-m>= -B I(I + 1) - m(m + 1) <-2,m-14l-2,m>=2B (I+ 1) - m(m + 1). The term values are then given by: 33 m) 3 3B I(I + 1) - m(m + 1):2-g 11IgD A 4 + -gj43H - 2D+A (m-) m)+ B 2[ I(I + 1) - m(m + 1)] 3B 2 I(I + 1) m(m 1) 11 m -Am OH + D + 33-m - - "'2 giOH+1 A(m1 2 glltH g - 2D +A(m 2-) E(1 H + 1 3B I(I + 1) - m(m + 1) 2 + 1)- m(m - 1) )HAm,+ -3 1 B of theglH s+ 2D + A (m +-) glH+A(m2 32 4 glH + 2D +A (m + - hv -2 If the second-order terms are neglected, the term values are linear in H. The dependence of the energy levels upon the magnetic field is then as shown in Fig. 6. The resonance conditions 2 2 E gO^ - ^^ H - 2D + Am I 1 B[ I(I+)-m(m+l)] 3B I(I + 1) - m(m - 1) (34) hv + 2D +- hv — A 2 2 1 1 2 2 23

WI LLOW RUN LABORATORIES TECHNICAL MEMORANDUM 2616-12-R/2900-116-R (1 ^ -/ I( \ +, B [ 1(1 +1)- m(m+ 1)] hv = E( - E (-, = g3H +Am + hv +2 (35) 2 2 2 3B (I+ 1) - m(m - 1) 3B I(I+ 1)- m(m +1) B [ I(+ 1) - m(m - 1)] _ +^M^^^~ _~~~^~ -{4 3 4 3 + hv - 2D —3A hv + 2D+-3A hvA 2 2 2 In the analysis given thus far, it has been assumed that all energy levels are distinct. However, in the region indicated by a circle in Fig. 6, the levels M = 1/2 and 3/2 cross, so that E(2~ m) = E( m + I). Consequently, it is necessary to revamp the perturbation calculation. For the degenerate or almost degenerate case, the submatrix for M = 1/2 and 3/2 partitions into two 1 x 1 matrixes and seven 2 x 2 matrixes. The 1 x 1 matrixes correspond to the states with the following wave functions and eigenvalues 737 3 03/2X7/2 E( ) =-2gH - D + A (36) 1/2X-7/2 E(2 )=gH + D 4A. The remaining 2 x 2 matrixes are of the form Q1/2Xm 3/2X m-1 |g2 XH + D y VI(I + 1) - m(m - 1) 1/ 2 Xm +-Am (37) 3 B I(I + 1) - m(m - 1) — g OH- D 3/2 Xm- 1 +3A(m- 1) 24

WI LLOW RUN LABORATORIES TEC H NICAL MEMORANDUM 2616-12-R/2900-1 16-R which gives for the eigenvalues E = E + 3H- D A — 4 (38) m 2 4 with 0 3 E = gllfH + Am -A (39) and X = ~B /I(I + 1) - m(m- 1). m 2 The above expressions can be written in a little more convenient form. Were it not for the off-diagonal elements, the levels for 01/2X mand 3/2Xm1 would cross when 1 1 3 3 lH + D +Am =l H - - D + —A(m - 1). (40) g11H 2 2 2 The magnetic field at which the levels cross then is given by (0) 3 g3H = 2D - Am + -A Writing then, H H (+ AH m m from Eq. (38) /2 1 2 2 2 E = E + gll m (41) and the 2 x 2 matrix can be written in the form l1/2Xm 03/2Xm-1 1/2Xm rn (bi!2Xm E0 - Oglif3AH X 0 2 ^4^^m rm (42) 01 3/2 Xm-l m E m+0 1 H 25

WI LLOW RUN LABORATORIES TECH N ICAL MEMORANDUM 2616- 12-R/2900-116-R The eigenvalues and the corresponding wave functions are E =E +X 1+ (43) = N (l/2Xm (3 + )3/2XmN m m03/ 2m -1' and / ~2 E =E0 -X I/ _ / 2 ~(44) E 0 = EEoy rmVl mm'/ 2 N[ (m ) 1l/2 m 3/2 m-1 where _m = gl/3AH /2.;m l m m 2 2 ). N = 2 (1 + + 1 + ). The dependence of the energies and wave functions are shown in Fig. 7 and 8. The resonance condition for the transition between levels -1/2 and Q is then given by hv = E E m hv = E ~-E (-+2' m) (45) = 2D + gll H - k' 2 ~ll' m m m Physically, this means that each of the hfs components will be split into two, with intensities in the ratio (a ) /(1), where 1 a - N ^~~~~~~~and~~ ___(~_46____~_ ~(46) and m +/1 + m N Consider then 3 hv = 2D + -A + hv. 26

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM 2616-12-R/2900- 116-R The resonance magnetic fields can be obtained by solving this equation. Suppose first, that Av = 0, i. e., 3 hv = 2D +-A 2 1 =m m 2X X AH ~ m gl3m Y }/-2g1j3 /3 B TVht- VI(I + 1)- m(m 1). The calculated spectra for several resonance frequencies are shown in Fig. 9. 27

WI LLOW RUN LABORATORIES TECHNICAL MEMORANDUM 2616- 12-R/2900- 116-R REFERENCES 1. Kikuchi, C., "Experimental Work on Ruby Masers," Am. Phys. Soc. Bull., 1958, Vol. 3, p. 369. 2. Lambe, J., Ager, R., and Kikuchi, C., "Electron Spin Resonance of V++ and V+++ in Corundum, " Am. Phys. Soc. Bull., 1959, Vol. 4, p. 261. 3. Low, W., "A Note Regarding the Spectrum of V3+ Complexes in Octahedral Fields," Z. Physik Chem., 1957, Vol. 13, p. 107. 4. Pryce, M. H. L., and Runciman, W. A., "The Absorption Spectrum of Vanadium Corundum," Disc. Faraday Soc., 1958, Vol. 26, p. 34. 5. Kikuchi, C., Lambe, J., Makhov, G., and Terhune, R. W., "Ruby as a Maser Material," J. App. Phys., 1959, Vol. 30, p. 1061. 6. Manenkov, A. A., and Prokhorov, A. M., "The Fine Structure of the Spectrum of the Paramagnetic Resonance of the Ion Cr3+ in Chromium Corundum," Soviet Phys. JETP, 1955, Vol. 1, p. 611. 7. Zaripov, M. A., and Shamonin, I., "Paramagnetic Resonance in Synthetic Ruby," Soviet Phys. JETP, 1956, Vol. 3, p. 171. 8. Geusic, J. E., "Paramagnetic Fine Structure of Cr+++ in a Single Ruby Crystal," Phys. Rev., 1956, Vol. 102, p. 1252. 9. Schulz-DuBois, E. O., "Paramagnetic Spectra of Substituted Sapphires - Part I. Ruby," Bell System Tech. J., 1959, Vol. 38, p. 271. 10. Cross, L., and Terhune, R. W., "Temperature Dependence of the ZeroField Splitting of Ruby," Am. Phys. Soc. Bull., 1958, Vol. 3, p. 37. 11. Bowers, K. D., and Owen, J., "Paramagnetic Resonance II," Repts. Prog. in Phys., 1955, Vol. 18, p. 304. 12. Fisher, R. A., and Goudsmit, S., "Hyperfine Structure in Ionized Bismuth," Phys. Rev., 1931, Vol. 37, p. 1057. 13. Tolansky, S., Hyperfine Structure in Line Spectra and Nuclear Spins, London, Methuen, 1948. 14. Wertz, J. E., Auzins, P., Griffiths, J. H. E., and Orten, J. W., "Electron Transfers Among Transition Elements in Magnesium Oxide, " Disc. Faraday Soc., 1958, Vol. 26, p. 66. 15. Lambe J., and Ager, R., "Microwave Cavities for Magnetic Resonance," Rev. Sci. Instr., 1959, Vol. 30, p. 599. 16. Zverev, G. M., and Prokhorov, A. M., "Electron Paramagnetic Resonance of the V+++ Ion in Sapphire, " Soviet Phys. JETP, 1958, Vol. 7, p. 1023. 17. McConnell, N. M., Porterfield, W. W., and Robertson, R. E., "Paramagnetic Resonance of Bis-Cyclopentadienyl Vanadium," J. Chem. Phys., 1959, Vol. 30, p. 442. 18. Mathews, J. H., and Lambe, J., "X-Ray Coloration of Ruby," Am. Phys. Soc. Bull., 1959, Vol. 4, p. 284. 28

WI LLOW RUN LABORATORIES TECH NICAL MEMORANDUM 2616-12-R/2900- 116-R REFERENCES (Continued) 19. Van Wieringen, J. S., "Paramagnetic Resonance of Divalent Manganese Incorporated in Various Lattices, " Disc. Faraday Soc., 1955, Vol. 19, p. 118. 20. Matsummura, O., "Electron Spin Resonance of Mn-Activated Phosphors," J. Phys. Soc. Japan, 1959, Vol. 14, p. 108. 21. Bleaney, B., Ingram, D. J. E., and Scovil, H. E. D., "Paramagnetic Resonance in Vanadous Ammonium Sulfate, " Proc. Phys. Soc., 1951, Vol. 64A, p. 39. 22. Kikuchi, C., Sirvetz, M. H., and Cohen, V. W., "Paramagnetic Resonance Hyperfine Structure of V50 and V51,", Phys. Rev., 1953, Vol. 92, p. 109. 23. Baker, J. M., and Bleaney, B., "Nuclear Spin of Vanadium 50, " Proc. Phys. Soc., 1952, Vol. 65A, p. 952. 24. Pake, G. E., and Sands, R. H., "Hyperfine Structure in the Paramagnetic Resonance of Vanadium Ions in Solution, " Phys. Rev., 1955, Vol. 98, p. 266A. 25. Pake, G. E., Weissmann, I., and Townsend, J., "Paramagnetic Resonance of Free Radicals," Disc. Faraday Soc., 1955, Vol. 19, p. 147. 26. Weiss, M. M., Walter, R. I., Gilliam, O. R., and Cohen, V. W., "Paramagnetic Resonance of V, " Am. Phys. Soc. Bull., 1937, Vol. 2, p. 31. 27. Low, W., "Paramagnetic Resonance Spectrum of Some Ions of the 3d and 4f Shells in Cubic Crystalline Fields, " Phys. Rev., 1956, Vol. 101, p. 1872L. 28. Anderson, W. A., and Piette, L. H., "Forbidden Ams = ~1, AmI = +1 Transitions in Vanadyl Chelate," J. Chem. Phys., 1959, Vol. 30, p. 591. 29. O'Reilly, D. E., "Paramagnetic Resonance of Vanadyl Etioporphyrin I," J. Chem. Phys., 1958, Vol. 29, p. 1188. 30. O'Reilly, D. E., "Erratum: Paramagnetic Resonance of Vanadyl Etioporphyrin I," J. Chem. Phys. 1959, Vol. 30, p. 591. 29

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM 2900-116-R DISTRIBUTION LIST 5, PROJECT MICHIGAN REPORTS 1 November 1959- Effective Date Copies - Addressee Copies - Addressee 2 Commanding General 1 Commandant, U. S. Army Engineer School U. S. Army Combat Surveillance Agency Fort Belvoir, Virginia 1124 N. Highland Street, Arlington 1, Virginia ATTN: Combat Developments Group 26 Commanding Officer U. S. Army Signal Research and Development Laboratory 1 Commandant, U. S. Army Aviation School Fort Monmouth, New Jersey Fort Rucker, Alabama ATTN: SIGFM/EL-DR 1 Commanding Officer, U. S. Army Signal Electronic Research Unit Post Office Box 205, Mountain View, California 1 Commanding General, U. S. Army Electronic Proving Ground Fort Huachuca, Arizona 1 Office of the Chief of Naval Operations, Op-07T, Building T-3 ATTN: Technical Library Department of the Navy, Washington 25, D. C. 1 Chief of Engineers, Department of the Army 3 Office of Naval Research (Code 463), Department of the Navy Washington 25, D. C. 17th and Constitution Avenue, N. W;, Washington 25, D. C. ATTN: Research and Development Division 1 Chief, Bureau of Ships, Department of the Navy ~~~1 ~~~Commanding General ~Washington 25, D. C. 1 Commanding General Quartermaster Research and Engineering Command ATTN: Code 312 U. S. Army, Natick, Massachusetts 2 Director, U. S. Naval Research Laboratory 1 Chief, Human Factors Research Division Washington 25, D. C. Office of the Chief of Research and Development ATTN: Code 2027 Department of the Army, Washington 25, D. C. 1 Commanding Officer, U. S. Navy Ordnance Laboratory 2 Commander, Army Rocket and Guided Missile AgencyCalifornia Corona, California Redstone Arsenal, Alabama ATTN: Library ATTN: Technical Library, ORDXR-OTL ATTN: Library 1 Commanding Officer and Director 1 Commanding Officer, Headquarters, U. S. Army Commanding Officer and Director Transportation Research and Engineering Command S N Electronics Laboratory Fort Eustis, Virginia California ATTN: Chief, Technical Services Division ATTN: Library 1 Department of the Air Force, Headquarters, USAF 1 Commanding General, Ordnance Tank-Automotive Command Department of the Air Force, Headquarters, USAF Washington 25, D. C. Detroit Arsenal, 28251 Van Dyke Avenue Washington 2,. C. Center Line, Michigan ATTN: Directorate of Requirements ATTN: Chief, ORDMC-RRS 1 Commander, Air Technical Intelligence Center Wright-Patterson Air Force Base, Ohio I Commanding General Army Medical Research and Development Command ATTN: AFCIN-4B/a Main Navy Building, Washington 25, D. C. 10 ASTIA (TIPCR) ATTN: Neuropsychiatry and Psychophysiology Research Branch Arlington Hall Station, Arlington 12, Virginia 5 Director 7 Commander, Wright Air Development Center U. S. Army Engineer Research and Development Laboratories Wright-Patterson Air Force Base, Ohio Fort Belvoir, Virginia (5) ATTN: WCLROR (1) ATTN: Chief, Topographic Engineer Department (1) ATTN: WCOSI - Library (3) ATTN: Chief, Electrical Engineering Department (1) ATTN: WCLDBFV (1) ATTN: Technical Documents Center 3 Commander, Rome Air Development Center 1 Commandant, U. S. Army War College Griffiss Air Force Base, New York Carlisle Barracks, Pennsylvania (1) ATTN: RCVSL-1 ATTN: Library (1) ATTN: RCWIR (1) ATTN: RCVH 1 Commandant, U. S. Army Command and General Staff College Fort Leavenworth, Kansas 2 Commander, Air Force Cambridge Research Center ATTN: Archives Laurence G. Hanscom Field, Bedford, Massachusetts ATTN: CRIS, Stop 36 2 Assistant Commandant, U. S. Army Artillery and Missile School ATTN: CRIS, Stop 36 Fort Sill, Oklahoma ~~~~Fort Sill, Oklahoma ~4 Central Intelligence Agency 2430 E. Street, N. W., Washington 25, D. C. 3 Assistant Commandant, U. S. Army Air Defense School Fort Bliss, Texas ATTN: OCR Mail Room 30

WI LLOW RUN LABORATORIES TECH N ICAL MEMORANDUM 2900-116-R DISTRIBUTION LIST 5 1 November 1959- Effective Date Copies - Addressee Copies - Addressee 5 National Aeronautics and Space Administration 1 Operations Research Office, The Johns Hopkins University 1520 H. Street, Northwest, Washington 25, D. C. 6935 Arlington Road, Bethesda, Maryland, Washington 14, D. C. ATTN: Chief Intelligence Division 1 U. S. Army Air Defense Human Research Unit Intelligence Division Fort Bliss, Texas ~~~Fort Bliss, Texas ~2 Cornell Aeronautical Laboratory, Inc. ATTN: Library 4455 Genesee Street, Buffalo 21, New York 2 Combat Surveillance Project A Li Cornell Aeronautical Laboratory, Inc. THRU: Bureau of Aeronautics Representative Box 168, Arlington 10, Virginia 4455 Genesee Street, Buffalo 21, New York ATTN: Technical Library ~ATTN: Technical Lihb~rary ~2 Control Systems Laboratory, University of Illinois 1 The RAND Corporation Urbana, Illinois 1700 Main Street ATTN: Librarian Santa Monica, California THRU: ONR Resident Representative ATTN: Library 1209 W. Illinois Street, Urbana, Illinois 1 Chief, U. S. Army Armor Human Research Unit 2 Director, Human Resources Research Office Fort Knox, Kentucky The George Washington University ATTN: Administrative Assistant P. O. Box 3596, Washington 7, D. C. ATTN: Library 1 Director of Research, U. S. Army Infantry Human Research Unit Massachusetts Institute of Technology 1 Massachusetts Institute of Technology P. O. Box 2086, Fort Benning, Georgia Research Laboratory of Electronics Research Laboratory of Electronics Cambridge 39, Massachusetts 1 Chief, U. S. Army Leadership Human Research Unit ATTN: Document Room 26-327 ATTN: Document Room 26-327 P. 0. Box 787, Presidio of Monterey, Calfiornia ATTN: Librarian 1 The U. S. Army Aviation HRU P. 0. Box 428, Fort Rucker, Alabama 1 Chief Scientist, Research and Development Division 2 Visibility Laboratory, Scripps Institution of Oceanography Office of the Chief Signal Officer, Department of the Army University of California, San Diego 52, California Washington 25, D. C. 1 U. S. Continental Army Command Liaison Officer I Stanford Research Institute, Document Center Project MICHIGAN, Willow Run Laboratories, Ypsilanti, Michigan Menlo Park, California 1 Commanding Officer, U. S. Army Liaison Group ATTN: Acquisitions Project MICHIGAN, Willow Run Laboratories, Ypsilanti, Michigan 31

AD Div. 25/6 UNCLASSIFIED AD Div. 25/6 UNCLASSIFIED Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Vanadium- Properties Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Vanadium-Properties SPIN RESONANCE OF V2+, V3+, V4+ IN a-Al203 by John Lambe I. Lambe, John, and SPIN RESONANCE OF V2+, V3+, V4+ IN a-A1203 by John Lambe I. Lambe, John, and and Chihiro Kikuchi. Technical memorandum. Nov 59. 29 p. Kikuchi, Chihiro and Chihiro Kikuchi. Technical memorandum. Nov 59. 29 p. Kikuchi, Chihiro incl. illus., table, 30 refs. II. Air Force Office of incl. illus., table, 30 refs. II. Air Force Office of (Technical memorandum no. 2616-12-R/2900-116-R) Scientific Research (Technical memorandum no. 2616-12-R/2900-116-R) Scientific Research (Contract AF49(638)-68/DA-36-039 SC-78801) III. U. S. Army Signal Corps (Contract AF49(638)-68/DA-36-039 SC-78801) III. U.S. Army Signal Corps Unclassified report IV. Contract AF49(638)-68 Unclassified report IV. Contract AF49(638)-68 Divalent vanadium has properties similar to those of trivalent SCo7r01 Divalent vanadium has properties similar to those of trivalent V. Conact chromium in sapphire, which has wide application in masers. chromium in sapphire, which has wide application in masers. The electron-spin resonance absorption properties of vanadium The electron-spin resonance absorption properties of vanadium sapphire are reported here. It is shown that vanadium normally sapphire are reported here. It is shown that vanadium normally is predominantly trivalent, with a small amount being in the is predominantly trivalent, with a small amount being in the tetravalent state. By x- or gamma-irradiation, vanadium is con- tetravalent state. By x- or gamma-irradiation, vanadium is converted to the divalent state. The hyperfine-structure component verted to the divalent state. The hyperfine-structure component separation for V2+, V3+, and V4+ are about 88, 110, and 140 gauss, Armed Services separation for V2+, V3+, and V4+ are about 88,. 110, and 140 gauss, Armed Services respectively. Because of its readily recognizable spin-resonance Technical Information Agency respectively. Because of its readily recognizable spin-resonance Technical Information Agency (over) UNCLASSIFIED (over) UNCLASSIFIED AD Div. 25/6 UNCLASSIFIED AD Div. 25/6 UNCLASSIFIED Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Vanadium -Properties Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Vanadium-Properties SPIN RESONANCE OF V2+, V3+, V4+ IN a-A1203 by John Lambe I. Lambe, John, and SPIN RESONANCE OF V2+, V3+, V4+ IN a-A1203 by John Lambe I. Lambe, John, and and Chihiro Kikuchi. Technical memorandum. Nov 59. 29 p. Kikuchi, Chihiro and Chihiro Kikuchi. Technical memorandum. Nov 59. 29 p. Kikuchi, Chihiro incl. illus., table, 30 refs. II. Air Force Office of incl. illus., table, 30 refs. II. Air Force Office of (Technical memorandum no. 2616-12-R/2900-116-R) Scientific Research (Technical memorandum no. 2616-12-R/2900-116-R) Scientific Research (Contract AF49(638)-68/DA-36-039 SC-78801) III. U. S. Army Signal Corps (Contract AF49(638)-68/DA-36-039 SC-78801) III. U.S. Army Signal Corps Unclassified report IV. Contract AF49(638)-68 Unclassified report IV. Contract AF49(638)-68 V. Contract DA-36-039 V. Contract DA-36-039 Divalent vanadium has properties similar to those of trivalent V. Contract DA-36-039 Divalent vanadium has properties similar to those of trivalent V. C - chromium in sapphire, which has wide application in masers. chromium in sapphire, which has wide application in masers. The electron-spin resonance absorption properties of vanadium The electron-spin resonance absorption properties of vanadium sapphire are reported here. It is shown that vanadium normally sapphire are reported here. It is shown that vanadium normally is predominantly trivalent, with a small amount being in the is predominantly trivalent, with a small amount being in the tetravalent state. By x- or gamma-irradiation, vanadium is con- tetravalent state. By x- or gamma-irradiation, vanadium is converted to the divalent state. The hyperfine-structure component verted to the divalent state. The hyperfine-structure component separation for V2+, V3+, and V4+ are about 88, 110, and 140 gauss, Armed Services separation for V2+, V3+, and V4+ are about 88, 110, and 140 gauss, Armed Services respectively. Because of its readily recognizable spin-resonance Technical Information Agency respectively. Because of its readily recognizable spin-resonance Technical Information Agency (over) UNCLASSIFIED (over) UNCLASSIFIED -+ -H +

AD UNCLASSIFIED AD UNCLASSIFIED signature due to its nuclear spin, and because of the ease of UNITERMS signature due to its nuclear spin, and because of the ease of UNITERMS producing different oxidation states, it is suggested that vanadium may Vanadium producing different oxidation states, it is suggested that vanadium may be a suitable probe with which to study ionization effects in certain C m be a suitable probe with which to study ionization effects in certain Chromium ~~~~~~~~~~~~~~~~~~Chromium solids. Chromium solids. Sphr ^^- ~~~~~~~ ~ ~ ~~~~~~~~~Sapphire " -Sphr Electron-spin Electron-spin Resonance Resonance Oxidation Oxidation Ionization Ionization Irradiation Irradiation UNCLASSIFIED UNCLASSIFIED AD UNCLASSIFIED AD UNCLASSIFIED signature due to its nuclear spin, and because of the ease of UNITERMS signature due to its nuclear spin, and because of the ease of UNITERMS producing different oxidation states, it is suggested that vanadium may Vanadium producing different oxidation states, it is suggested that vanadium may V be a suitable probe with which to study ionization effects in certain. be a suitable probe with which to study ionization effects in certain solids. Sapphire Sapphir Electron-spin Electron-spin Resonance Resonance Oxidation Oxidation Ionization Ionization Irradiation Irradiation UNCLASSIFIED UNCLASSIFIED

AD Div. 25/6 UNCLASSIFIED AD Div. 25/6 UNCLASSIFIED Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Vanadium - Properties Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Vanadium-Properties SPIN RESONANCE OF V2+, V3+, V4+ IN 0e-A203 by John Lambe I. Lambe, John, and SPIN RESONANCE OF V2+, V3+, V4+ IN 0-A1203 by John Lambe I. Lambe, John, and and Chihiro Kikuchi. Technical memorandum. Nov 59. 29 p. Kikuchi, Chihiro and Chihiro Kikuchi. Technical memorandum. Nov 59. 29 p. KikuchiChihiro incl. illus., table, 30 refs. II. Air Force Office of incl. illus., table, 30 refs. II. Air Force Office of (Technical memorandum no. 2616-12-R/2900-116-R) Scientific Research (Technical memorandum no. 2616-12-R/2900-116-R) Scientific Research (Contract AF49(638)-68/DA-36-039 SC-78801) III. U. S. Army Signal Corps (Contract AF49(638)-68/DA-36-039 SC-78801) III. U.S. Army Signal Corpa Unclassified report IV. Contract AF49(638)-68 Unclassified report IV. Contract AF49(638)-68 Divalent vanadium has properties similar to those of trivalent C C 70ata Divalent vanadium has properties similar to those of trivalent Cont chromium in sapphire, which has wide application in masers. chromium in sapphire, which has wide application in masers. The electron-spin resonance absorption properties of vanadium The electron-spin resonance absorption properties of vanadium sapphire are reported here. It is shown that vanadium normally sapphire are reported here. It is shown that vanadium normally is predominantly trivalent, with a small amount being in the is predominantly trivalent, with a small amount being in the tetravalent state. By x- or gamma-irradiation, vanadium is con- tetravalent state. By x- or gamma-irradiation, vanadium is converted to the divalent state. The hyperfine-structure component verted to the divalent state. The hyperfine-structure component separation for V2+, V3+, and V4+ are about 88, 110, and 140 gauss, Armed Services separation for V2+, V3+, and V4+ are about 88,. 110, and 140 gauss, Armed Services respectively. Because of its readily recognizable spin-resonance Technical Information Agency respectively. Because of its readily recognizable spin-resonance Technical Information Agency (over) UNCLASSIFIED (over) UNCLASSIFIED AD Div. 25/6 UNCLASSIFIED AD Div. 25/6 UNCLASSIFIED Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Vanadium - Properties Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Vanadium-Properties SPIN RESONANCE OF V2+, V3+, V4+ IN e-A1203 by John Lambe I. Lambe, John, and SPIN RESONANCE OF V2+, V3+, V4+ IN a-A1203 by John Lambe I. Lambs, John, and and Chihiro Kikuchi. Technical memorandum. Nov 59. 29 p. Kikuchi, Chihiro and Chihiro Kikuchi. Technical memorandum. Nov 59. 29 p. Kikuchi, Chihiro incl. illus., table, 30 refs. II. Air Force Office of incl. illus., table, 30 refs. II. Air Force Office of (Technical memorandum no. 2616-12-R/2900-116-R) Scientific Research (Technical memorandum no. 2616-12-R/2900-116-R) Scientific Research (Contract AF49(638)-68/DA-36-039 SC-78801) III. U. S. Army Signal Corps (Contract AF49(638)-68/DA-36-039 SC-78801) III. U.S. Army Signal Corps Unclassified report IV. Contract AF49(638)-68 Unclassified report IV. Contract AF49(638)-68 V. Contract DA-36-039 V. Contract DA-36-039 Divalent vanadium has properties similar to those of trivalent Divalent vanadium has properties similar to those of trivalent chromium in sapphire, which has wide application in masers. chromium in sapphire, which has wide application in masers. The electron-spin resonance absorption properties of vanadium The electron-spin resonance absorption properties of vanadium sapphire are reported here. It is shown that vanadium normally sapphire are reported here. It is shown that vanadium normally is predominantly trivalent, with a small amount being in the is predominantly trivalent, with a small amount being in the tetravalent state. By x- or gamma-irradiation, vanadium is con- tetravalent state. By x- or gamma-irradiation, vanadium is converted to the divalent state. The hyperfine-structure component verted to the divalent state. The hyperfine-structure component separation for V2+, V3~, and V4+ are about 88, 110, and 140 gauss, Armed Services separation for V2+, V3+, and V4+ are about 88, 110, and 140 gauss, Armed Services respectively. Because of its readily recognizable spin-resonance Technical Information Agency respectively. Because of its readily recognizable spin-resonance Technical Information Agency (over) UNCLASSIFIED (over) UNCLASSIFIED -H +

AD UNCLASSIFIED AD UNCLASSIFIED signature due to its nuclear spin, and because of the ease of UNITERMS signature due to its nuclear spin, and because of the ease of UNITERMS producing different oxidation states, it is suggested that vanadium may Vanadium producing different oxidation states, it is suggested that vanadium may be a suitable probe with which to study ionization effects in certain C m be a suitable probe with which to study ionization effects in certain solids. SChromium solids.Chromium ^^- ~~~~~~~ ~ ~ ~~~~~~~Sapphire "'Sapphire Electron-spin Electron-spin Resonance Resonance Oxidation Oxidation Ionization Ionization Irradiation Irradiation UNC LASSIFIEDUNLSIED ^ ^S AD UNCLASSIFIED ADUNCLASSIFIED signature due to its nuclear spin, and because of the ease of UNITERMS signature due to its nuclear spin, and because of the ease of UNITERMS producing different oxidation states, it is suggested that vanadium may Vanadium producing different oxidation states, it is suggested that vanadium may adium be a suitable probe with which to study ionization effects in certain Chroiumbe a suitable probe with which to study ionization effects in certain " ~~~~~~~~Chromium soldsnCromium solids. Sapphire Sapphire Electron-spin Electron-spin Resonance Resonance Oxidation Oxidation Ionization Ionization Irradiation Irradiation UNCLASSIFIED UNCLASSIFIED