Electron‐Diffraction Structural Study of Polymeric Gaseous Hydrogen Fluoride
dc.contributor.author | Janzen, Jay | en_US |
dc.contributor.author | Bartell, Lawrence S. | en_US |
dc.date.accessioned | 2010-05-06T21:38:45Z | |
dc.date.available | 2010-05-06T21:38:45Z | |
dc.date.issued | 1969-04-15 | en_US |
dc.identifier.citation | Janzen, Jay; Bartell, L. S. (1969). "Electron‐Diffraction Structural Study of Polymeric Gaseous Hydrogen Fluoride." The Journal of Chemical Physics 50(8): 3611-3618. <http://hdl.handle.net/2027.42/70108> | en_US |
dc.identifier.uri | https://hdl.handle.net/2027.42/70108 | |
dc.description.abstract | Electron diffraction patterns with molecular interference features extending beyond s = 35Å−1s=35Å−1 were obtained for gaseous self‐associated HF introduced under its own vapor pressure at −19° and at +22°C through a conventional nozzle system into a 40‐kV electron beam. The diffraction patterns and their dependence on temperature are best explained with the hypothesis that the monomer and a puckered, cyclic hexamer were the only appreciable constituents of the scattering vapors. Mean FFF angles in the hexamer were found to be only about 104°, in contrast with the 120° angles reported for the infinite planar zigzag chains in crystalline HF at −125°C. This pucker may simply be a consequence of thermal bending of the extremely flexible ring. Indeed, the experimental radial distribution function is so smeared out by large ring‐bending amplitudes that the data cannot distinguish between boatlike and chair conformations. It is likely that the free (HF)6 molecules sweep randomly through both conformations in their thermal undulations. At the two temperatures studied the hydrogen‐bonded FF distances were 2.525 and 2.533 Å, with standard errors of 0.003 Å, in comparison with the solid‐state result of 2.49 ± 0.01 Å. Corresponding FF amplitudes of vibration were 0.089 and 0.101 Å (±0.003 Å), respectively. Perhaps 70% at −19° and 45% at 22° of the hydrogen bonds were asymmetric with covalent FH distances 0.040 Å longer than those in the monomer molecules. The data suggest, however, that the remainder of the ring protons migrate a substantial distance off‐axis to a more symmetrical disposition between the fluorines. | en_US |
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dc.format.extent | 631644 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 | Electron‐Diffraction Structural Study of Polymeric Gaseous Hydrogen Fluoride | 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 | Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48104 | en_US |
dc.description.bitstreamurl | http://deepblue.lib.umich.edu/bitstream/2027.42/70108/2/JCPSA6-50-8-3611-1.pdf | |
dc.identifier.doi | 10.1063/1.1671593 | en_US |
dc.identifier.source | The Journal of Chemical Physics | en_US |
dc.identifier.citedreference | J. Janzen and L. S. Bartell, U.S. Atomic Energy Commission, IS‐1940, 47 pp., 1968. This supplement of the present study reviews relevant HF literature, refines and extends published analyses, and concludes in favor of the description of Ref. 2, below. The essential conclusions are that the principal constituents of HF vapor are monomer, dimer, and a cyclic hexamer, and that the amount of dimer is minor under the present conditions. The existence of other oligomers is likely, but in concentrations which are, for most nonspectroscopic experimental purposes, completely negligible by comparison with the HF+(HF)2+(HF)6HF+(HF)2+(HF)6 total at room temperature and below. The possibility of ring formation from six‐membered chains at a very small cost in entropy of ring closure is viewed as the source of special stability which makes the cyclic hexamer the predominating polymeric species. | en_US |
dc.identifier.citedreference | E. U. Franck and F. Meyer, Z. Elektrochem. 63, 571 (1959). | en_US |
dc.identifier.citedreference | The Ph.D. thesis of J. Janzen (Iowa State University, 1968) may be consulted for additional details. | en_US |
dc.identifier.citedreference | L. S. Bartell, Kozo Kuchitsu, and R. J. deNeui, J. Chem. Phys. 35, 1211 (1961). | en_US |
dc.identifier.citedreference | B. L. Carroll, unpublished Ph.D. thesis, Iowa State University, Ames, Iowa, 1963, pp. 5–8. | en_US |
dc.identifier.citedreference | J. P. Guillory, unpublished Ph.D. thesis, Iowa State University, Ames, Iowa, 1965, p. 60. | en_US |
dc.identifier.citedreference | S. Shibata and L. S. Bartell, J. Chem. Phys. 42, 1147 (1965). | en_US |
dc.identifier.citedreference | L. S. Bartell and L. O. Brockway, Phys. Rev. 90, 833 (1953). | en_US |
dc.identifier.citedreference | L. S. Bartell, D. A. Kohl, B. L. Carroll, and R. M. Gavin, Jr., J. Chem. Phys. 42, 3079 (1965). | en_US |
dc.identifier.citedreference | D. J. Dahm (personal communication, Ames, Iowa, 1965). | en_US |
dc.identifier.citedreference | D. A. Kohl and R. A. Bonham, J. Chem. Phys. 47, 1634 (1967); D. A. Kohl, unpublished Ph.D. thesis, Indiana University, Bloomington, Ind., 1966), Chap. V. | en_US |
dc.identifier.citedreference | L. S. Bartell and L. O. Brockway, J. Appl. Phys. 24, 656 (1953). | en_US |
dc.identifier.citedreference | Reference 4, footnote 7. | en_US |
dc.identifier.citedreference | L. S. Bartell, J. Appl. Phys. 31, 252 (1960). | en_US |
dc.identifier.citedreference | Compare Fig. 1 of the present paper with that of L. S. Bartell and J. P. Guillory, J. Chem. Phys. 43, 647 (1965). Recall that a correction for the edge effect was applied in the present study. | en_US |
dc.identifier.citedreference | R. A. Bonham and L. S. Bartell, J. Chem. Phys. 31, 702 (1959). | en_US |
dc.identifier.citedreference | R. A. Bonham and T. Ukaji, J. Chem. Phys. 36, 72 (1962). | en_US |
dc.identifier.citedreference | Refer to subsequent section on “⋯distances less than 2 Å.” | en_US |
dc.identifier.citedreference | An examination of the literature (Ref. 1) disclosed no compelling evidence for the existence, in vapors at equilibrium, of any other polymeric species which could make larger contributions. See specifically Appendix A of Ref. 1 and Fig. 12 of Ref. 2. Note, also, that in the final adiabatic free expansion of the gas jet into the vacuum chamber, it is expected that the temperature will drop markedly as the pressure drops. This expansion lasts only for about a microsecond before the electron beam is encountered. Even if it is assumed that equilibrium is maintained, no gross change in monomer‐hexamer ratio is expected. From the heat capacities and heats of polymerization summarized in Refs. 1 and 2, it can be calculated that the effects of T and P changes nearly cancel each other insofar as equilibrium composition is concerned. | en_US |
dc.identifier.citedreference | M. Atoji and W. N. Lipscomb, Acta Cryst. 7, 173 (1954). | en_US |
dc.identifier.citedreference | B. B. Howard, J. Chem. Phys. 39, 2524 (1963), Fig. 2. | en_US |
dc.identifier.citedreference | S. H. Bauer, J. Y. Beach, and J. H. Simons, J. Am. Chem. Soc. 61, 19 (1939). | en_US |
dc.identifier.citedreference | Y. Morino, S. J. Cyvin, K. Kuchitsu, and T. Iijima, J. Chem. Phys. 36, 1109 (1962). | en_US |
dc.identifier.citedreference | Y. Morino, K. Kuchitsu, and M. Tanimoto (to be published). | en_US |
dc.identifier.citedreference | K. Kuchitsu and L. S. Bartell, J. Chem. Phys. 35, 1945 (1961). | en_US |
dc.identifier.citedreference | G. Herzberg, Spectra of Diatomic Molecules (D. Van Nostrand Co., Inc., Princeton, N.J., 1950), 2nd ed., p. 536. | en_US |
dc.identifier.citedreference | See dashed curves of Fig. 3. | en_US |
dc.identifier.citedreference | R. H. Hughes, R. J. Martin, and N. D. Coggeshall, J. Chem. Phys. 24, 489 (1956), and D. Hadzi, Ed., Hydrogen Bonding (Pergamon Press, Inc., New York, 1959). | en_US |
dc.identifier.citedreference | D. F. Smith, J. Phys. Chem. 28, 1040 (1958). | en_US |
dc.identifier.citedreference | J. S. Kittelberger and D. F. Hornig, J. Chem. Phys. 46, 3099 (1967). | en_US |
dc.identifier.citedreference | D. F. Smith, J. Mol. Spectry. 3, 473 (1959). | en_US |
dc.owningcollname | Physics, Department of |
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