Kinetics and dynamics of near-resonant vibrational energy transfer in gas ensembles of atmospheric interest

Abstract

This study of near-resonant, vibration–vibration (V–V) gas-phase energy transfer in diatomic molecules uses the theoretical/computational method, of Marsh & McCaffery (Marsh & McCaffery 2002 J. Chem. Phys. 117 , 503 ( doi:10.1063/1.1489998 )) The method uses the angular momentum (AM) theoretical formalism to compute quantum-state populations within the component molecules of large, non-equilibrium, gas mixtures as the component species proceed to equilibration. Computed quantum-state populations are displayed in a number of formats that reveal the detailed mechanism of the near-resonant V–V process. Further, the evolution of quantum-state populations, for each species present, may be followed as the number of collision cycles increases, displaying the kinetics of evolution for each quantum state of the ensemble's molecules. These features are illustrated for ensembles containing vibrationally excited N 2 in H 2 , O 2 and N 2 initially in their ground states. This article is part of the theme issue ‘Modern theoretical chemistry’.

Full-dimensional quantum studies of vibrational energy transfer dynamics between H2O and Ar: theory assessing experiment

“…In the current system, the scattering into different final vibrational states clearly shows a propensity for the energy gap law. 10 Fig. 2 revealed this clear trend in the magnitude of inelastic scattering ICSs for different final vibrational states, decreasing in the order (0, 0, 1) > (1, 0, 0) > (0, 2, 0) > (0, 1, 0) > (0, 0, 0).…”

“…Within each specific final vibrational manifold, the ICSs are also dominated by those MISs whose internal energies are nearest to those of the initial MIS, apparently also dictated by the energy gap law. 10…”

“…9 A key issue in quantum state specific energy transfer dynamics is whether the collision is governed by the so-called gap laws. The energy gap law, which stipulates that the transition probability is the largest for energy transfer between the initial and final states with roughly the same internal energy, 10 has been observed in many systems. [11][12][13] Another gap law involves the rotational angular momentum: collisions favor those that conserve the sum of rotational angular momenta of the collision partners.…”

Breakdown of energy transfer gap laws revealed by full-dimensional quantum scattering between HF molecules

“…Collision-induced energy transfer is a fundamentally important process in many gas-phase chemical environments, such as combustion 1 , atmospheric chemistry 2 , astrochemistry 3 , and chemical laser engineering 4 . It is responsible for a wide array of macroscopic phenomena, such as heating and cooling as well as energy transport.…”

Modern theoretical chemistry: the legacy of Prof. John N. Murrell

“…Calculated transport coefficients point to the presence of a single spin-orbit component in the complementary experiments. Moving from single collision events to ensembles of molecules, McCaffery [10] shows how an angular momentum model can effectively compute the evolution of quantum state populations in gaseous mixture under non-equilibrium conditions. The results demonstrate how near-resonant vibrational energy transfer has a profound influence on the time scale over which equilibrium can be achieved.…”