Mode-Specific Energy Disposal in the Four-Atom Reaction OH + D ₂ → HOD + D

Abstract

Experiments, employing crossed molecular beams, with vibrational state resolution have been performed on the simplest four-atom reaction, OH + D2 --> HOD + D. In good agreement with the most recent quantum scattering predictions, mode-specific reaction dynamics is observed, with vibration in the newly formed oxygen-deuterium bond preferentially excited to v = 2. This demonstrates that quantum theoretical calculations, which in the past decade have achieved remarkable accuracy for three-atom reactions involving three dimensions, have progressed to the point where it is now possible to accurately predict energy disposal in four-atom reactions involving six dimensions.

Classical versus quantum vibrational state distributions for the benchmark polyatomic reaction OH+D2: Checking the validity of the QCT method

“…Quasi-classical trajectory (QCT) calculations on the benchmark polyatomic reaction OH + D 2 were recently performed [10] on the OC potential energy surface (OC-PES) [3] at the conditions of the experiment of Davis and co-workers [4]. The overall agreement was satisfying, but one of the three main vibrational states available was found to be significantly lower than its experimental measure [10].…”

“…Initial conditions were selected to reproduce the experiment of Davis and co-workers [4], with a collision energy of 6.6 kcal/ mol, and the reactants OH and D 2 in their ro-vibrational ground states.…”

“…The dynamics are mode specific, i.e., only a few product vibrational states are populated [4]. The three most populated states are labeled (0, 2), (0, 1) and (1,1), the first and second numbers being the quantum numbers for the bending and OD local stretching modes, respectively.…”

“…HOD + D is a benchmark polyatomic bimolecular reaction [2][3][4][5][6][7][8][9][10][11]. It is the analogue of F + H 2 ?…”

“…FH + H [12] for tetratomic processes. About 10 years ago, impressive experimental measurements by the high resolution D atom Rydberg tagging method allowed Davis and co-workers to construct the angle-velocity, or flux, contour map [4]. This observable, which tells us where the products go and how fast, is among the most refined observables of chemical reactivity [1].…”