Polarization and M-dependent effects in rotationally inelastic collisions of open-shell diatomic molecules: Ar--NO(X /sup 2/Pi/sub 1//sub ///sub 2/)

Journal Article · Wed Feb 15 04:00:00 EST 1984 · J. Chem. Phys.; (United States)

OSTI ID:5171455

Alexander, M H; Orlikowski, T

Our earlier quantum study of collisions of NO(X /sup 2/Pi) with Ar (T. Orlikowski and M. H. Alexander, J. Chem. Phys. 79, 6006 (1983)) is here extended to the calculation of M-dependent cross sections in the case of laboratory-frame quantization, as would be appropriate to collision cell experiments. The calculations confirm the earlier prediction of Alexander and Davis (J. Chem. Phys. 79, 227 (1983)) that the JM..-->..J, -M cross sections will be vanishingly small for transitions which preserve the e or f ..lambda..-doublet symmetry. This propensity rule is here shown to be rigorous within the coupled-states (CS) limit. The effect of collisions on the initial rotational density matrix can be expressed in terms of multipole transfer efficiencies. The calculated values for Ar--NO collisions indicate that e/f changing collisions are much more strongly depolarizing, in the sense of destroying the multipole moments of the initial density matrix, than those collisions which preserve the e/f ..lambda..-doublet label. Since the circular or linear polarization of the fluorescence from a laser excited molecule can be written in terms of these multipole transfer efficiencies, we are able to use the Ar--NO(X /sup 2/Pi) cross sections reported here to model qualitatively the depolarization effects one might expect to see in experiments involving excited molecules in /sup 2/Pi electronic states.

• Research Organization: Department of Chemistry, University of Maryland, College Park, Maryland 20742
• OSTI ID: 5171455
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 80:4; 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
CHALCOGENIDES
COLLISIONS
ELEMENTS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
FLUIDS
GASES
MOLECULE COLLISIONS
NITRIC OXIDE
NITROGEN COMPOUNDS
NITROGEN OXIDES
NONMETALS
OXIDES
OXYGEN COMPOUNDS
POLARIZATION
RARE GASES
ROTATIONAL STATES