State-resolved rotationally inelastic cross sections of CaCl (X /sup 2/. sigma. /sup +/) with polar molecule targets

Journal Article · Thu Jan 31 23:00:00 EST 1985 · J. Chem. Phys.; (United States)

OSTI ID:6162972

Dagdigian, P J; Bullman, S J

State-to-state rotationally inelastic integral cross sections for the scattering of Ca/sup 35/Cl(X /sup 2/..sigma../sup +/) by the polar molecules HCl, HCN, and SO/sub 2/ have been determined. CaCl in the incident N = 2 e level is prepared by electric quadrupole state selection of a supersonic beam, and final states are detected by single-mode cw dye laser fluorescence excitation in the B /sup 2/..sigma../sup +/--X /sup 2/..sigma../sup +/ band system. The cross sections clearly display a propensity for conservation of fine-structure level, i.e., e ..-->.. e, in collisional rotational transitions, predicted by Alexander (J. Chem. Phys. 76, 3637 (1982)) from examination of the fully quantum description of the dynamics. The magnitudes of the cross sections are also found to be large, as expected from the long range of the electrostatic dipole--dipole interaction. However, in spite of the relatively high collision energy, the sudden approximation considerably overestimates the cross sections and does not explain their nonmonotonic ordering with target dipole moment. The adiabatically corrected sudden (ACS) theory, on the other hand, satisfactorily explains the absolute magnitudes of the cross sections and, more importantly, provides an explanation for the dependence on target molecule properties. The peculiar dependence of the cross sections on target molecule dipole moment was found to be a result of differences in the adiabatic damping of the sudden cross sections due to the energy level spacings, and hence rotational constants, in the target molecule.

• Research Organization: Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218
• OSTI ID: 6162972
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 82:3; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ALKALINE EARTH METAL COMPOUNDS
BEAMS
CALCIUM CHLORIDES
CALCIUM COMPOUNDS
CALCIUM HALIDES
CHALCOGENIDES
CHLORIDES
CHLORINE COMPOUNDS
COLLISIONS
CROSS SECTIONS
CYANIDES
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
HALIDES
HALOGEN COMPOUNDS
HYDROCHLORIC ACID
HYDROCYANIC ACID
HYDROGEN COMPOUNDS
INORGANIC ACIDS
INTEGRAL CROSS SECTIONS
MOLECULAR BEAMS
MOLECULE COLLISIONS
MOLECULE-MOLECULE COLLISIONS
OXIDES
OXYGEN COMPOUNDS
ROTATIONAL STATES
SULFUR COMPOUNDS
SULFUR DIOXIDE
SULFUR OXIDES