Collisional energy transfer of highly excited polyatomic molecules as a stochastic process

Graphical abstract: The energy dependence of conditional probability at the fixed reduced time νt. Highlights: ► The energy dependence of conditional probability at the fixed reduced time νt. ► The strong collisions are shown to manifest themselves in the distribution pattern. ► The cooled molecules, losing all their energy, give rise to thermal distribution. - Abstract: Collisional energy transfer between highly excited molecules and bath gas is considered as a stochastic process occurring in energy space. It is assumed that the density of vibrational states of polyatomic molecules is energy-dependent. An exact solution to the master equation for conditional probability density is given in terms of simple analytical formulas for weak and strong collisions. The bulk-average moments of internal energy and the average moments of energy transfer are calculated analytically. The place occupied by the collisional transfer of vibrational energy among other stochastic processes is discussed.