Energy transfer in molecular collisions

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1981

OSTI ID:6375168

Vilallonga, E F

Vibrational and rotational energy transfer in hyperthermal molecular collisions are investigated by means of time-correlation function methods. Within this approach, the collisional differential cross section is expressed as the Fourier transform of the time correlation function of the transition operator, which evolves in time in accordance with the internal motions of the noninteracting molecules. The correlation function includes from the outset the experimental averages over initial distributions, so that only quantities directly related to experimental measurements need be calculated. The present approach allows the systematic introduction of approximations to the transition operator, which are based on models of the intermolecular forces and of the collision dynamics; the resulting correlation functions are readily evaluated for most polyatomics without need of internal-state or partial-wave expansions. In particular, a many-body description of the dynamics, together with a multicenter representation of itermolecular forces, shows that, at hyperthermal energies, large-angle atom-polyatomic scattering is related to the correlation of the positions of pairs of atoms that constitute the target. The atom-pair correlation functions are evaluated by means of cumulant expansiions and of Green-function techniques. The multicenter representation of the intermolecular potential is investigated, and multicenter surfaces are developed for the interaction of Li/sup +/ with CO and with CO/sub 2/. Combining these developments, the differential cross sections are calculated for the vibrational and rotational excitation of N/sub 2/, CO and CO/sub 2/ in collisions with hyperthermal Li/sup +/ ions.

• Research Organization: Florida Univ., Gainesville (USA)
• OSTI ID: 6375168
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ANALYTICAL SOLUTION
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHARGED PARTICLES
COLLISIONS
CORRELATION FUNCTIONS
CROSS SECTIONS
DATA
DIFFERENTIAL CROSS SECTIONS
DYNAMICS
ELEMENTS
ENERGY TRANSFER
ENERGY-LEVEL TRANSITIONS
EXCITATION
FUNCTIONS
INFORMATION
INTERMOLECULAR FORCES
ION COLLISIONS
ION-MOLECULE COLLISIONS
IONS
LITHIUM IONS
MECHANICS
MOLECULE COLLISIONS
MOLECULE-MOLECULE COLLISIONS
MOLECULES
NITROGEN
NONMETALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
POLYATOMIC MOLECULES
POTENTIALS
THEORETICAL DATA
TIME DEPENDENCE