Excitation and dissociation mechanisms in molecules with application to mercuric halide laser system

Conference · Fri Jan 01 04:00:00 EST 1982

OSTI ID:6334926

Spence, D; Wang, R G; Dillon, M A

Although the mercuric halide laser systems have received intensive study in recent years, being one of only two efficient electronic-transition lasers known, the precise collisional mechanisms leding to HgBr(B), formation and subsequent fluorescence are still imperfectly understood. The initial suggestion that direct collisional excitation of, say, HgBr/sub 2/, by electrons (analogous to photoionization), i.e., HgBr/sub 2/ + e ..-->.. HgBr(b) + Br + e, was the dominant mechanism, was temporarily abandoned when a measurement by Allison and Zare yielded a cross section of only < 1 x 10/sup -20/ cm/sup 2/ for low incident electron energy HgBr(B-x) fluorescence, much too small to explain the observed laser efficiency. Subsequent explanations for HgBr(B) formation included energy transfer from excited N/sub 2/ or rare gases, electronic recombination of HgBr/sub 2//sup +/, or dissociative electron attachment. Though it has recently been demonstrated that electronic energy transfer does play a role in HgBr(B) formation in the presence of N/sub 2/ or X/sub e/ buffers, modeling studies of e-beam sustained discharges have now conclusively shown that direct electron-impact excitation of mercuric halides, is indeed the dominant laser mechanism. The technique of electron-energy-loss spectroscopy was used to obtain pseudo-optical absorption spectra in HgBr/sub 2/ and HgCl/sub 2/. Results are presented and discussed. (WHK)

• Research Organization: Argonne National Lab., IL (USA)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6334926
• Report Number(s): CONF-821073-2; ON: DE83008870
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420300* -- Engineering-- Lasers-- (-1989)
640304 -- Atomic
Molecular &amp; Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ABSORPTION SPECTRA
BROMIDES
BROMINE COMPOUNDS
CHLORIDES
CHLORINE COMPOUNDS
COLLISIONS
DISSOCIATION
ELECTRON COLLISIONS
ELECTRON-MOLECULE COLLISIONS
ENERGY-LEVEL TRANSITIONS
EXCITATION
GAS LASERS
HALIDES
HALOGEN COMPOUNDS
LASER MATERIALS
LASERS
MATERIALS
MERCURY BROMIDES
MERCURY CHLORIDES
MERCURY COMPOUNDS
MERCURY HALIDES
METAL VAPOR LASERS
MOLECULE COLLISIONS
SPECTRA