Fluorescence and dissociative energy transfer in high pressure Ar--HCN mixtures excited by relativistic electrons

Journal Article · Wed Dec 01 04:00:00 EST 1976 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.432964· OSTI ID:7344573

Zamir, E; Szoeke, A; Osgood, R

Studies of the radiation from Ar--HCN and Ar--H/sub 2/O mixtures, excited by relativistic electrons from a Febetron 706 electron gun, are presented. The energy deposited by the electrons channels rapidly into the Ar* and Ar/sub 2/* states; then by dissociative collisions with HCN it is transferred partly into the CN(B) state and partly into a reservoir state (most probably the CN(A) state) with near unit efficiency. Fluorescence emission from the electronic states A (/sup 2/Pi/sub i/) and B (/sup 2/..sigma../sup +/) of the CN radical, as well as the emission from the Ar/sub 2/* excimer state, were measured for an Ar pressure range of 750--9000 torr (15--180 psi (absolute)), and an HCN pressure range of 0.2--13 torr. The quenching rates of Ar* metastable and the Ar/sub 2/* excimer states, by collision with HCN molecules, were measured to be 6 x 10/sup -10/ and 1 x 10/sup -9/ cm/sup 3/ sec/sup -1/, respectively. Our results suggest that population inversion can be achieved by collisional dissociation of simple molecules with excited rare gas atoms and excimers. Indeed the peak CN(B) population density was found to be 1.5 x 10/sup 15/ cm/sup -3/, which corresponds to an optical gain for the B--X transition of 0.4 cm/sup -1/ if the ground state is empty. A computer kinetic model is presented that explains the time dependence and intensity of the CN(B) emission. In Ar--H/sub 2/O mixtures the reaction rate for quenching of Ar/sub 2/* excimer by H/sub 2/O molecules is extremely high; however, the yield into the OH(A /sup 2/..sigma../sup +/) is only 3%. (AIP)

• Research Organization: Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
• OSTI ID: 7344573
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 65:11; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ARGON
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
COLLISIONS
DISPERSIONS
DISSOCIATION
ELECTRON COLLISIONS
ELECTRON-ATOM COLLISIONS
ELECTRON-MOLECULE COLLISIONS
ELEMENTS
ENERGY LEVELS
ENERGY RANGE
ENERGY TRANSFER
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXCITED STATES
FLUIDS
FLUORESCENCE
GASES
HYDROCYANIC ACID
HYDROGEN COMPOUNDS
INORGANIC ACIDS
LUMINESCENCE
MIXTURES
MOLECULE COLLISIONS
NONMETALS
POPULATION INVERSION
RARE GASES
RELATIVISTIC RANGE