Trajectory studies on the collisional relaxation of highly excited benzenes by mono- and polyatomic colliders

Building transition probabilities for any condition using reduced cumulative energy transfer functions in H2O–H2O collisions

The energy transfer process between highly vibrationally excited H(2)O in thermal equilibrium with a gas bath of H(2)O at different internal energies and temperatures has been studied by classical trajectory calculations. The results were analyzed using a cumulative probability distribution Q(DeltaE) of the amount of energy transferred, obtained by direct count of the number of trajectories that transfer an amount of energy equal to or greater than a certain value DeltaE. Scaling Q(DeltaE) in terms of the mean down and up energies transferred for each group of trajectories results in a unique distribution. This fact and the use of detailed balance constrains were used to propose a methodology that make it possible to build the whole P(E('),E) for any condition by knowing DeltaE and a series of parameters that depend only on the system under study.

Relaxation dynamics of highly vibrationally excited picoline isomers (E(vib) = 38 300 cm(-1)) with CO2: the role of state density in impulsive collisions

Strong collisions of highly vibrationally excited picoline isomers and CO2 (00(0)0) were investigated using high resolution transient IR absorption probing to investigate the role of donor state density. Vibrationally excited 3-picoline and 4-picoline (3-methylpyridine and 4 methylpyridine) with E(vib) = 38300 cm(-1) were prepared by 266 nm excitation followed by rapid internal conversion. Transient IR probe measurements of the nascent rotational and translational energy gain in CO2 (00(0)0) show that large DeltaE collisions for 3- and 4-picoline are similar to those for excited 2-picoline. The probability distributions for the large DeltaE energy transfer of the three isomers have similar dependence on DeltaE. The results are compared with other earlier results demonstrating that the shape of the large DeltaE probability distribution correlates with the DeltaE dependence of the donor vibrational state density. The results are discussed in terms of the GRETCHEN model for collisional relaxation.

Temperature Dependence of Collisional Energy Transfer in Highly Excited Aromatics Studied by Classical Trajectory Calculations

The temperature dependence of the gas-phase collisional relaxation of highly vibrationally excited aromatic molecules has been studied using large scale classical trajectory calculations. The investigations have focused on azulene collisions with different colliders (He, Ar and N