Multiple rainbow singularities in product rotational distributions of exothermic collisions: A probe for the /ital P//sub 4/ anisotropy of the system Ar(/sup 1/S/sub 0/)+N/sub 2/(/ital C//sup 3//Pi//sub u/)
The effect on product rotational distributions of the energy released during exothermic processes is investigated with the model of collisions with a rigid, anisotropic shell. With increasing exothermicity, rotational-rainbow maxima become apparent in model integral cross sections for rotational excitation, due to the increasing importance of the final-state repulsion with respect to that in the initial state. Such rainbow maxima are expected to occur in product distributions of excitation transfer, chemical reactions, and dissociation processes. Two different rotational-rainbow maxima can appear even for homonuclear product molecules when the interaction potential contains substantial anisotropy described by a fourth-order Legendre polynomial /ital P//sub 4/. This type of anisotropy can explain the bimodal rotational distribution of the product N/sub 2/(C) of the exothermic excitation-transfer collision Ar/sup */(/sup 3/P/sub 0,2/)+N/sub 2/(X), with an energy release ..delta../ital E/=701 and 521 meV for the /sup 3/P/sub 0/ and /sup 3/P/sub 2/ states, respectively, as measured by Nguyen and Sadeghi at a temperature of 90 K (=11 meV). The scaling of the rainbow positions with the exothermicity is reproduced. The best agreement with the experimental data is obtained with a ratio of anisotropy parameters /ital c//sub 4//c/sub 2/=1.8. Such anisotropy may be caused by the promotion of a 2sigma/sub /ital u// electron to a 2..pi../sub /ital g// orbital when going from the /ital X/ to the /ital C/ state of N/sub 2/. .AE
- Research Organization:
- Department of Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands(NL)
- OSTI ID:
- 6141154
- Journal Information:
- Phys. Rev. A; (United States), Vol. 39:11
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ARGON
ATOM-MOLECULE COLLISIONS
NITROGEN
ANISOTROPY
EXCITATION
POTENTIALS
ROTATIONAL STATES
SINGULARITY
ATOM COLLISIONS
COLLISIONS
ELEMENTS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
FLUIDS
GASES
MOLECULE COLLISIONS
NONMETALS
RARE GASES
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena