Collisional coupling and relaxation of N/sub 2/(B/sup 3/Pi/sub g/) and N/sub 2/ (W /sup 3/. delta. /sub u/) vibrational levels in Ar and Ne

Journal Article · Thu Sep 15 04:00:00 EDT 1983 · J. Chem. Phys.; (United States)

OSTI ID:5720969

Sadeghi, N; Setser, D W

Laser excitation from N/sub 2/(A /sup 3/..sigma../sup +//sub u/, v = 0-6) in Ne and Ar carrier gas in a flowing afterglow apparatus has been used to prepare N/sub 2/(B /sup 3/Pi/sub g/) molecules in individual levels from v = 3-10. The subsequent N/sub 2/(B-A) fluorescence intensity was observed to study the coupling and relaxation kinetics of N/sub 2/(B /sup 3/Pi/sub g/, v = 2-10). The decay curves from each level show double (or higher) exponential relaxation. The first component is assigned as primarily the rapid coupling of the N/sub 2/(B /sup 3/Pi/sub g/,v) and N/sub 2/(W /sup 3/..delta../sub u/, v or v+1) levels, however, the N/sub 2/ (B' /sup 3/..sigma../sup -//sub u/, v-4) levels also may be involved for N/sub 2/(B, v> or =5). The slowest decay component represents the subsequent relaxation of the coupled levels. The combination of the two steps is equivalent to apparent stepwise vibrational relaxation of N/sub 2/ (B /sup 3/Pi/sub g/, v), such relaxation occurs even at low Ar pressures because of the large rate constants and long radiative lifetimes of N/sub 2/(B) and N/sub 2/(W). The coupling pattern between N/sub 2/(B) and N/sub 2/(W) is analyzed, and rate constants are assigned to elementary steps in the relaxation sequence and the scheme is evaluated. From the analysis of the slow decay components in argon, estimates (20-90 ..mu..s) are obtained for the radiative lifetimes for the reservoir levels, which are assigned as N/sub 2/ (W /sup 3/..delta../sub u/, v) for N/sub 2/(B, v< or =4) and N/sub 2/(W /sup 3/..delta../sub u/, v or v+1) levels plus N/sub 2/(B'/sup 3/..sigma../sup -//sub u/, v-4) levels, for some cases, for N/sub 2/(B, v> or =5).

• Research Organization: Laboratoire de Spectrometrie Physique, Universite de Grenoble, BP68-38402 Saint-Martin d'Heres, France
• OSTI ID: 5720969
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 79:6; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular &amp; Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
AFTERGLOW
ARGON
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
COLLISIONS
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY LEVELS
EXCITED STATES
FLUIDS
FLUORESCENCE
GASES
LASER RADIATION
LIFETIME
LUMINESCENCE
MOLECULE COLLISIONS
NEON
NITROGEN
NONMETALS
RADIATIONS
RARE GASES
RELAXATION
VIBRATIONAL STATES