Polarized x-ray emission studies of methyl chloride and the chlorofluoromethanes

Journal Article · Fri Mar 01 00:00:00 EST 1991 · Physical Review, A; (USA)

DOI:https://doi.org/10.1103/PhysRevA.43.2353· OSTI ID:6204226

Lindle, D W; Cowan, P L; Jach, T; LaVilla, R E; Deslattes, R D ^[1]; Perera, R C.C. ^[2]

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1. National Institute of Standards and Technology, Gaithersburg, Maryland (US)
2. Advanced Light Source, Accelerator and Fusion Research Division, Lawrence Berkeley Laboratory, Berkeley, California (US)

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 (CH{sub 3}Cl) and the chlorofluoromethanes (CF{sub 3}Cl, CF{sub 2}Cl{sub 2}, and CFCl{sub 3}) in the gas phase. Upon selective excitation using monochromatic synchrotron radiation in the Cl {ital K}-edge (Cl 1s) near-threshold region, polarization-selective x-ray emission studies reveal highly polarized molecular {ital valence} x-ray fluorescence for all four molecules. The degree {ital and} the orientation of the polarized emission are observed to be sensitive to the incident excitation energy near the Cl {ital K} edge. 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.

• OSTI ID: 6204226
• Journal Information: Physical Review, A; (USA), Vol. 43:5; ISSN 1050-2947
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
FLUORINATED ALIPHATIC HYDROCARBONS
X-RAY FLUORESCENCE ANALYSIS
METHYL CHLORIDE
EXCITATION
MOLECULAR STRUCTURE
POLARIZATION
SYMMETRY
SYNCHROTRON RADIATION
BREMSSTRAHLUNG
CHEMICAL ANALYSIS
CHLORINATED ALIPHATIC HYDROCARBONS
ELECTROMAGNETIC RADIATION
ENERGY-LEVEL TRANSITIONS
HALOGENATED ALIPHATIC HYDROCARBONS
NONDESTRUCTIVE ANALYSIS
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
RADIATIONS
X-RAY EMISSION ANALYSIS
640302* - Atomic
Molecular & Chemical Physics- Atomic & Molecular Properties & Theory