Excitation and quenching reactions in E-beam excited He/H/sub 2/O and He/CH/sub 3/CN systems

Journal Article · Sun Jan 15 04:00:00 EST 1978 · J. Chem. Phys.; (United States)

OSTI ID:5338369

Binns, W R; Ahl, J L

This paper describes observations made in the afterglow of an electron beam discharge into high-pressure mixtures of He/H/sub 2/O and He/CH/sub 3/CN and assesses the laser potential of these systems. Emission spectra and time histories at visible and near uv wavelengths were obtained spectroscopically. OH(A/sup 2/..sigma -->..X/sup 2/Pi/sub i/) emission (306.8< or =lambda< or =310.9 nm) predominated in the He/H/sub 2/O system, and CN(B /sup 2/..sigma../sup +/..-->..X /sup 2/..sigma../sup +/) emission (385.0< or =lambda< or =391.6 nm) predominated in the He/CH/sub 3/CN system. The suggested pumping reactions operative in these systems are the dissociative charge exchange reactions He/sub 2//sup +/ + H/sub 2/O..-->..OH(A)+HeH/sup +/+He and He/sub 2//sup +/+CH/sub 3/CN..-->..CN(B)+CH/sub 3//sup +/+2He. The rate constants for these reactions have been determined to be (1.3 +- 0.2) x 10/sup -10/ and (1.1 +- 0.3) x 10/sup -10/ cm/sup 3//s, respectively. The He/sub 2//sup +/ quenching rate constants for H/sub 2/O and for CH/sub 3/CN were found to be (1.2 +- 0.2) x 10/sup -9/ and (3.5 +- 0.7) x 10/sup -9/ cm/sup 3//s, respectively. The OH(A) quenching rate constant for H/sub 2/O was determined to be (4.2 +- 0.4) x 10/sup -10/ cm/sup 3//s, and the CN(B) quenching rate constant for CH/sub 3/CN was found to be (1.4 +- 0.3) x 10/sup -10/ cm/sup 3//s. The OH(A) yield (number of excited molecules produced/number of He/sup +/ ions formed) was found to be 11%; the CN(B) yield was 3%. Maximum laser efficiencies for these systems were calculated and determined to be 0.5% and 0.1%, respectively.

• Research Organization: McDonnell Douglas Research Laboratories, St. Louis, Missouri 63166
• OSTI ID: 5338369
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 68:2; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420300* -- Engineering-- Lasers-- (-1989)
BEAMS
BINARY MIXTURES
CRYOGENIC FLUIDS
DISPERSIONS
EFFICIENCY
ELECTRIC DISCHARGES
ELECTRON BEAMS
ELEMENTS
EMISSION SPECTRA
ENERGY-LEVEL TRANSITIONS
EXCITATION
FLUIDS
GAS LASERS
GASES
HELIUM
LASERS
LEPTON BEAMS
MIXTURES
NONMETALS
ORGANIC COMPOUNDS
PARTICLE BEAMS
RARE GASES
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ULTRAVIOLET SPECTRA
VAPORS
VISIBLE SPECTRA
WATER VAPOR