Excitation of the 4. 3-. mu. m bands of CO/sub 2/ by low-energy electrons
Rate coefficients for the excitation of the 4.3-..mu..m bands of CO/sub 2/ by low-energy electrons in CO/sub 2/ have been measured using a drift-tube technique. The CO/sub 2/ density ((1.5 to 7) x 10/sup 17/ molecules/cm/sup 3/) was chosen to maximize the radiation reaching the detector. Line-by-line transmission calculations were used to take into account the absorption of 4.3-..mu..m radiation. A small fraction of the approximately 10/sup -8/ W of the 4.3-..mu..m radiation produced by the approximately 10/sup -7/-A electron current was incident on an InSb photovoltaic detector. The detector calibration and absorption calculations were checked by measuring the readily calculated excitation coefficients for vibrational excitation of N/sub 2/ containing a small concentration of CO/sub 2/. For pure CO/sub 2/ the number of molecules capable of emitting 4.3-..mu..m radiation produced per cm of electron drift and per CO/sub 2/ molecule varied from 10/sup -17/ cm/sup -2/ at E/N = 6 x 10/sup -17/ V cm/sup 2/ to 5.4 x 10/sup -16/ cm/sup -2/ at E/N = 4 x 10/sup -16/ V cm/sup 2/. Here E is the electric field and N is total gas density. The excitation coefficients at lower E/N are much larger than estimated previously. A set of vibrational excitation cross sections is obtained for CO/sub 2/ which is consistent with the excitation coefficient data and with most of the published electron-beam data. (AIP)
- Research Organization:
- Joint Institute for Laboratory Astrophysics, National Bureau of Standards and University of Colorado, Boulder, Colorado 80309
- OSTI ID:
- 7346117
- Journal Information:
- Phys. Rev., A; (United States), Journal Name: Phys. Rev., A; (United States) Vol. 14:2; ISSN PLRAA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
COLLISIONS
ELECTRON COLLISIONS
ELECTRON-MOLECULE COLLISIONS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXCITED STATES
INFRARED SPECTRA
MOLECULE COLLISIONS
OXIDES
OXYGEN COMPOUNDS
SPECTRA
VIBRATIONAL STATES