Scattering angle dependence of electron impact excitation: Intensity variation within a vibrational progression

Journal Article · Sun Jan 22 04:00:00 EST 1995 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.468888· OSTI ID:6713469

Dillon, M; Kimura, M ^[1]; Buenker, R J; Hirsch, G; Li, Y; Chantranupong, L ^[2]

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1. Argonne National Laboratory, Argonne, Illinois 60439 (United States)
2. Bergische Universitaet, Gesamthochschule Wuppertal, Fachbereich 9, Theoretische Chemie, Gausstrasse 20, D-42097 Wuppertal (Germany)

Intensity distributions of electronic transitions in O[sub 2] and CO within a vibrational progression resulting from electron impact excitation are studied theoretically and experimentally. The [ital multireference] [ital single]- [ital and] [ital double]-[ital excitation] [ital configuration] [ital interaction] (MRD-CI) method is used to elucidate details of selected electronic transitions. In particular, the adiabatic MRD-CI approach can account for the variation of the Franck--Condon envelope with scattering angle that has been reported for the [ital B] [sup 1][Sigma][sup +][l arrow][ital X] [sup 1][Sigma][sup +] transition in CO and also was recently observed in the [ital B][prime] [sup 3][Sigma][sup [minus]][sub [ital u]][l arrow][ital X] [sup 3][Sigma][sup [minus]][sub [ital g]] transition of O[sub 2]. This behavior contrasts with the relative stability of the intensity distribution observed within the CO [ital A] [sup 1][Pi][l arrow][ital X] [sup 1][Sigma][sup +] vibrational progression. In the former cases the excited state undergoes changes with internuclear separation because of the presence of an avoided crossing. Since a transition from the zeroth vibrational level in the ground electronic state to an individual vibrational level in the excited electronic state tends to select a particular internuclear distance ([ital R] centroid), each vibrational band may behave as a transition to a separate electronic level. This happens because the excited-state wave function undergoes a compositional change with internuclear separation between the adiabatic partners of the avoided crossing.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6713469
• Journal Information: Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 102:4; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

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74 ATOMIC AND MOLECULAR PHYSICS
ADIABATIC APPROXIMATION
AMPLITUDES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
COLLISIONS
CONFIGURATION INTERACTION
DISTANCE
ELECTRON COLLISIONS
ELECTRON SPECTROSCOPY
ELECTRON-MOLECULE COLLISIONS
ELECTRONIC STRUCTURE
ELEMENTS
ENERGY LEVELS
ENERGY LOSSES
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXCITED STATES
FRANCK-CONDON PRINCIPLE
FUNCTIONS
GROUND STATES
INTERATOMIC DISTANCES
LOSSES
MOLECULE COLLISIONS
NONMETALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
SPECTROSCOPY
VARIATIONS
VIBRATIONAL STATES
WAVE FUNCTIONS