Theoretical study of an unusual reactive collision Cs(7p)+H/sub 2/. -->. CsH+H. Diabatic approach of the collinear collision potential energy surfaces

Journal Article · Thu May 01 00:00:00 EDT 1986 · J. Chem. Phys.; (United States)

OSTI ID:5892741

Gadea, F X; Spiegelmann, F; Pelissier, M; Malrieu, J P

The Cs(7p)+(X /sup 1/summation/sup +//sub g/, v = 0) H/sub 2/..-->..(X /sup 2/summation/sup +/, v = 0) CsH+H reactive collision was recently experimentally observed from a crossed beam experiment by Crepin et al. This reaction is rather unusual since it starts from a highly excited state of the system (11th potential surface) and must reach the ground state surface in the product channel without energy loss. Accurate nonempirical CI calculations of the potential energy surface for the collinear collision are reported, using large basis sets and a nonempirical relativistic pseudopotential for the Cs atom. The adiabatic potential surfaces, which exhibit irregular behavior, are reinterpreted in terms of an ab initio nearly diabatic effective Hamiltonian spanned by five neutral repulsive channels Cs(6s) x H/sub 2/, Cs(6p) x H/sub 2/,..., Cs(7p) x H/sub 2/ and an ionic very flat Cs/sup +/H/sup -//sub 2/ channel which tends to the product wave function (Cs/sup +/H/sup -/) x H. The intersection of these diabatic potential surfaces are accessible from the entrance energy and this picture supports a harpooning mechanism, the 7p electron jumping on the H/sub 2/ system at R/sub CsH/ roughly-equal6 bohr, the reactive systems being those which remain diabatically on this ionic surface through the avoided crossings with the lower Cs(7s) x H/sub 2/,...,Cs(6s) x H/sub 2/ neutral surfaces. The electronic couplings between the diabatic states are given as functions of the R/sub CsH/ and R/sub HH/ coordinates and their behavior is qualitatively understood.

• Research Organization: Laboratoire de Physique Quantique, Universite Paul Sabatier, Unite Associee au C.N.R.S. no. 505, 118 Route de Narbonne, 31062 Toulouse Cedex, France
• OSTI ID: 5892741
• Journal Information: J. Chem. Phys.; (United States), Vol. 84:9
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ATOM-MOLECULE COLLISIONS
CHEMICAL REACTIONS
CESIUM
HYDROGEN
ATOMIC BEAMS
CESIUM HYDRIDES
CONFIGURATION INTERACTION
MOLECULAR BEAMS
ALKALI METAL COMPOUNDS
ALKALI METALS
ATOM COLLISIONS
BEAMS
CESIUM COMPOUNDS
COLLISIONS
ELEMENTS
HYDRIDES
HYDROGEN COMPOUNDS
METALS
MOLECULE COLLISIONS
NONMETALS
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena