Time-dependent Wave Packet Quantum Scattering Study of Reaction S(3P)+H2→HS+H on a New ab initio Potential Energy Surface 3A′

Experimental and theoretical studies of the reactions of ground-state sulfur atoms with hydrogen and deuterium

The gas-phase kinetics of S(³P) atoms with H₂ and D₂ have been studied via the laser flash photolysis-resonance fluorescence technique. S atoms were generated by pulsed photolysis of CS₂ at 193 nm and monitored by time-resolved fluorescence at 181 nm. The rate coefficients for H₂ (k₁) and D₂ (k₂), respectively, are summarized as k₁(600-1110 K) = 3.0 × 10^-9 exp-1.317×10⁵-2.703×10⁷K/T8.314 T/K cm³ molecule^-1 s^-1 and k₂(770-1110 K) = 2.2 × 10^-14 (T/298 K)^3.55 exp(-5420 K/T) cm³ molecule^-1 s^-1. Error limits are discussed in the text. The rate coefficients for formation of SH(SD) + H(D) on a newly developed triplet potential energy surface were characterized via ring polymer molecular dynamics and canonical variational transition-state theory. There is excellent agreement above about 1000 K between theory and experiment. At lower temperatures, the experimental rate coefficient is substantially larger than the results computed for the adiabatic reaction, suggesting a significant role for intersystem crossing to the singlet potential energy surface at lower temperatures.

State-resolved time-dependent wave packet and quasiclassical trajectory studies of the adiabatic reaction S(3P) + HD on the (1(3)A″) state

Time-dependent wave packet (TDWP) and quasiclassical trajectory (QCT) calculations have been carried out for the reaction S(3P) + HD(X1Σg+) at the lowest 13A″ state with both rotational and vibrational excitations of reactant HD. The calculated integral cross sections from QCT agree fairly well with the TDWP calculations. The reaction probability results from TDWP show that the reaction displays a strong tendency to the SD channel. When the reactant HD is vibrationally excited, both channels are promoted apparently. The vibration of the HD bond tends to reduce the difference of reactivity between the two channels. The detailed state-to-state differential cross sections (DCSs) are calculated. These distributions show some significant characters of the barrier-type reactions. At the same time, the scattering width of product SD has a certain relationship with its rotation excitation. For the vector properties, P(θr), P(r), and P(θr,r) distributions are calculated by QCT, and the increased collision energy weakens the rotational polarization of the SD molecule.