Polarized X-ray-emission Studies of Methyl Chloride and the Chlorofluoromethanes

Authors

Dennis W. Lindle, University of Nevada, Las VegasFollow
P. L. Cowan, Argonne National Laboratory
T. Jach, National Institute ofStandards and Technology,
R. E. LaVilla, National Institute ofStandards and Technology,
R. D. Deslattes, National Institute ofStandards and Technology,
Rupert C. Perera, Lawrence Berkeley National LaboratoryFollow

Document Type

Article

Publication Date

3-1991

Publication Title

Physical Review A

Volume

43

Issue

5

First page number:

2353

Last page number:

2366

Abstract

A new technique sensitive to molecular orientation and geometry, and based on measuring the polarization of x-ray emission, has been applied to the Cl-containing molecules methyl chloride (CH₃Cl) and the chlorofluoromethanes (CF₃Cl, CF₂Cl₂, and CFCl₃) in the gas phase. Upon selective excitation using monochromatic synchrotron radiation in the Cl K-edge (Cl 1s) near-threshold region, polarization-selective x-ray emission studies reveal highly polarized molecular valence x-ray fluorescence for all four molecules. The degree and the orientation of the polarized emission are observed to be sensitive to the incident excitation energy near the Cl Kedge. In some cases, the polarization direction for x-ray emission reverses for small changes in incident excitation energy (a few eV). It is shown that the polarized x-ray emission technique can be used to infer, directly from experiment, symmetries of occupied and unoccupied valence molecular orbitals, an- isotropies in absorption and emission, and orientational and geometrical information. It is suggested that the x-ray polarized-fluorescence phenomenon, reported here for simple molecules, can be used as a new approach to study more complicated systems in a variety of environments.

Keywords

Chlorofluoromethane; Dichloromethane; X-ray spectroscopy; X-rays — Polarization

Disciplines

Analytical Chemistry | Atomic, Molecular and Optical Physics | Biological and Chemical Physics | Elementary Particles and Fields and String Theory | Physical Chemistry

Language

English

Permissions

Copyright American Physical Society, used with permission

Repository Citation

Lindle, D. W., Cowan, P. L., Jach, T., LaVilla, R. E., Deslattes, R. D., Perera, R. C. (1991). Polarized X-ray-emission Studies of Methyl Chloride and the Chlorofluoromethanes. Physical Review A, 43(5), 2353-2366.
https://digitalscholarship.unlv.edu/chem_fac_articles/76