Velocity Dependence of the Differential Cross Sections for the Scattering of Atomic Beams of K and Cs by Hg
dc.contributor.author | Morse, Fred A. | en_US |
dc.contributor.author | Bernstein, Richard B. | en_US |
dc.date.accessioned | 2010-05-06T21:20:21Z | |
dc.date.available | 2010-05-06T21:20:21Z | |
dc.date.issued | 1962-11-01 | en_US |
dc.identifier.citation | Morse, Fred A.; Bernstein, Richard B. (1962). "Velocity Dependence of the Differential Cross Sections for the Scattering of Atomic Beams of K and Cs by Hg." The Journal of Chemical Physics 37(9): 2019-2027. <http://hdl.handle.net/2027.42/69910> | en_US |
dc.identifier.uri | https://hdl.handle.net/2027.42/69910 | |
dc.description.abstract | Measurements of the velocity dependence of the angular intensity distribution of potassium and cesium beams scattered by a crossed beam of mercury are presented. The alkali beam was velocity selected, with a triangular velocity distribution (half‐intensity width 4.7% of peak velocity); the velocity was varied over the range 185–1000 m/sec. The Hg beam had a thermal distribution; the average Hg speed was ∼235 meters per second. The scattering data have been converted to the center‐of‐mass system. The angular distributions show the expected strong forward scattering and evidence the phenomenon of rainbow scattering. The energy dependence of the rainbow angle is used to evaluate the interatomic potential well depth, interpreted as the dissociation energy De of the 2Σ+ molecular ground state. Values (in erg×1014) thus obtained (±5%) are 7.46 for KHg and 7.72 for CsHg. Absolute values of differential cross sections could not be obtained; only relative cross sections D(θ) are reported. The observed low‐angle behavior D(θ) ∝θ‐ 7/3 serves as direct experimental confirmation of the r—6 dependence of the long‐range attractive potential for K☒Hg and Cs☒Hg systems. | en_US |
dc.format.extent | 3102 bytes | |
dc.format.extent | 605565 bytes | |
dc.format.mimetype | text/plain | |
dc.format.mimetype | application/pdf | |
dc.publisher | The American Institute of Physics | en_US |
dc.rights | © The American Institute of Physics | en_US |
dc.title | Velocity Dependence of the Differential Cross Sections for the Scattering of Atomic Beams of K and Cs by Hg | en_US |
dc.type | Article | en_US |
dc.subject.hlbsecondlevel | Physics | en_US |
dc.subject.hlbtoplevel | Science | en_US |
dc.description.peerreviewed | Peer Reviewed | en_US |
dc.contributor.affiliationum | Chemistry Department, University of Michigan, Ann Arbor | en_US |
dc.description.bitstreamurl | http://deepblue.lib.umich.edu/bitstream/2027.42/69910/2/JCPSA6-37-9-2019-1.pdf | |
dc.identifier.doi | 10.1063/1.1733421 | en_US |
dc.identifier.source | The Journal of Chemical Physics | en_US |
dc.identifier.citedreference | F. A. Morse, R. B. Bernstein, and H. U. Hostettler, J. Chem. Phys. 36, 1947 (1962). | en_US |
dc.identifier.citedreference | H. U. Hostettler and R. B. Bernstein, Rev. Sci. Instr. 31, 872 (1960). | en_US |
dc.identifier.citedreference | H. U. Hostettler and R. B. Bernstein, Phys. Rev. Letters 5, 318 (1960). These experiments involved the scattering of velocity‐selected Li beams by Hg. Because of the lower reduced mass μ of this system and the deeper potential well depth ϵ12ϵ12 (compared to the K‐Hg and Cs‐Hg systems), comparable values of the reduced relative kinetic energy K would have required higher Li speeds than attainable with the apparatus. Thus rainbow angles1 for the Li‐Hg system would be expected to be well outside the angular range of the experiments. | en_US |
dc.identifier.citedreference | F. A. Morse, Ph.D. dissertation, University of Michigan, Ann Arbor, Michigan, June 1962. | en_US |
dc.identifier.citedreference | P. Kusch, Notes on Angular Resolution (unpublished notes), Columbia University, New York July 1960. | en_US |
dc.identifier.citedreference | The c.m. data‐conversion problem for crossed molecular beams has been considered and analyzed (in part) by several workers: (a) H. U. Hostettler and R. B. Bernstein, University of Michigan (unpublished notes), September 1958; (b) D. R. Herschbach, University of California, Rept. UCRL‐9379, April 1960; (c) R. Helbing and H. Pauly, Diplomarbeit (Helbing) University of Bonn, 1961; (d) S. Datz, D. R. Herschbach, and E. H. Taylor, J. Chem. Phys. 35, 1549 (1961); (e) E. F. Greene and J. Ross, Brown University (private communication), March 1962. | en_US |
dc.identifier.citedreference | The averaging of n2n2 is not a serious problem since it may be regarded as constant; for most crossed beam experiments the secondary beam path length across the primary beam is usually very short and its transmission through the scattering zone is. nearly 100%. | en_US |
dc.identifier.citedreference | H. S. W. Massey and C. B. O. Mohr, Proc. Roy. Soc. (London) A144, 188 (1934). | en_US |
dc.identifier.citedreference | H. Pauly, Z. Naturforsch. 14A, 1083 (1959). | en_US |
dc.identifier.citedreference | H. Pauly, University of Bonn (private communication), March 1961. | en_US |
dc.identifier.citedreference | TK = 450 °K,TK=450°K, THg = 365 °K.THg=365°K. | en_US |
dc.identifier.citedreference | See, for example, E. H. Kennard, Kinetic Theory of Gases (McGraw‐Hill Book Company, Inc., New York, 1938), p. 120. Assume V(r) = −C/r6V(r)=−C∕r6 and small θ (i.e., sinθ ≅ θsinθ≅θ). | en_US |
dc.identifier.citedreference | R. Helbing and H. Pauly [Z. Physik (to be published); also reference 6(c)] have obtained similar evidence for the systems K‐Ar, ‐Xe, ‐Br2,‐Br2, etc., from measurements of the low‐angle scattering of thermal K beams (no velocity selection). | en_US |
dc.identifier.citedreference | See, for example, procedures in J. O. Hirschfelder, C. F. Curtiss, and R. B. Bird, Molecular Theory of Gases and Liquids (John Wiley & Sons, Inc., New York, 1954). | en_US |
dc.identifier.citedreference | E. A. Mason, J. Chem. Phys. 26, 667 (1957). | en_US |
dc.identifier.citedreference | K. W. Ford and J. A. Wheeler [Ann. Phys. (N.Y.) 7, 287 (1959)] have shown that the classical rainbow infinity (cusp) becomes a smooth maximum according to the semiclassical analysis. | en_US |
dc.identifier.citedreference | One of the major difficulties in evaluating 2n̄2 is the question of “cloud formation” in front of the secondary oven slit, and the attendant scattering which produces a serious alteration of the velocity distribution and an appreciably lower net intensity of the secondary beam at the target zone. For THg = 365 °K,THg=365°K, PHg = 0.16 mm Hg;cf.PHg=0.16mmHg;cf. TK = 450 °K,TK=450°K, PK = 2.5×10−3 mm Hg.PK=2.5×10−3mmHg. | en_US |
dc.identifier.citedreference | E. W. Rothe and R. B. Bernstein, J. Chem. Phys. 31, 1619 (1959). | en_US |
dc.identifier.citedreference | From Landolt‐Börnstein, Physikalisch‐Chemische Tabellen (Springer‐Verlag, Berlin, 1950) 6th ed., I. Band, 3. Teil, with α calculated from molar polarization on p. 514; a corresponding value is listed in I. Band, 1. Teil, p. 401. Since the calculated C depends nearly linearly upon α (Hg) and also upon α (K or Cs), the uncertainty in α values lead to serious errors. In addition, the SK formula is only approximate; thus the C values quoted must be regarded as semiquantitative estimates. Ratios of C’s are, of course, more reliable due to cancellations. | en_US |
dc.identifier.citedreference | A. Salop, E. Pollack, and B. Bederson, Phys. Rev. 124, 1431 (1961). | en_US |
dc.owningcollname | Physics, Department of |
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