ANALYSIS OF ATOMIC AND MOLECULAR COLLISIONS

摘要

The components of a non-equilibrium gas to be analysed are identified, and the initial distribution of the populations of each component among rotational and vibrational quantum states provided together with the initial conditions of the gas. Initial condition information for each atom or molecule is stored in respective arrays associated with each component of the gas (step 1). A collision frequency and total number of collisions to be considered are specified. A collision to be analysed is identified by randomly selecting a pair of atoms or molecules (but weighted with respect to the probability of a collision between that pair of atoms/molecules occurring in the system) (step 3). The initial condition information for each atom or molecule is then used to determine the final post-collisional condition of each colliding atom or molecule (steps 7-15) using the angular momentum method as described herein. The final rotational and vibrational quantum states, angular momentum and recoil velocity for each atom or molecule are determined and used to update the corresponding values stored in the arrays of the initial condition information (step 17). The analysis is repeated until each atom or molecule has undergone the number of collisions it would be expected to undergo before the system reaches equilibrium (step 19).