Low-energy electron attachment to SF6 at sub-meV resolution using a tunable laser photoelectron method

Electron attachment to sulfur hexafluoride is studied using a photoelectron source of ultralow-energy electrons with sub-meV resolution. Vacuum-ultraviolet laser radiation produced through nonlinear-optical techniques is used to photoionize xenon at and above its P-2(1/2)o ionization limit. The resulting photoelectrons interact with sulfur hexafluoride admixed to the xenon. The electron energy is continuously scanned from 0 to 127 meV, with a resolution of 0.1 meV at threshold. Computational modeling indicates that the attachment cross section is well described by the Wigner threshold law at electron energies less than about 5 meV. Data at higher energies are best described by the Wigner s-wave form, or by a Klots form with beta =0.228. Cusps are observed at the omega (6), omega (1), and omega (3) vibrational modes of SF6. While the omega (1) and omega (3) cusps have their maxima at the spectroscopic energies of 97.1 and 117.6 meV, respectively, the omega (6) cusp has its maximum at 46 meV, nearly 3 meV higher than its spectroscopic value of 43.2+/-0.4 meV. Possible explanations are considered, such as a low-l angular-momentum barrier, an overtone mode of SF6 excited by the collision, or clustering. The definitive cause of this shift is not understood.

Title	Low-energy electron attachment to SF6 at sub-meV resolution using a tunable laser photoelectron method
Creator	Chutjian, A.
	Kortyna, Andrew
	Darrach, M.
	Howe, P. T.
Publisher	Physical Review A
Academic Department	Physics
Division	Natural Sciences
Organization	Lafayette College
Date Issued	October 2001
Date Available	2013-02-25T20:00:27Z
Type	Article
Language	English
Bibliographic Citation	Howe, P. T., et al. (2001 Oct) "Low-energy electron attachment to SF6 at sub-meV resolution using a tunable laser photoelectron method." Physical Review A 64 (4): 042706-1--042796-8.
Standard Identifier	Handle 10385/1119
Standard Identifier	DOI 10.1103/PhysRevA.64.042706
Permalink	http://hdl.handle.net/10385/1119
Rights Statement	In Copyright
Rights Holders	The American Physical Society