Internal energy of HCl upon photolysis of 2-chloropropene at 193 nm investigated with time-resolved Fourier-transform spectroscopy and quasiclassical trajectories

Abstract

Following photodissociation of 2-chloropropene (H(2)CCClCH(3)) at 193 nm, vibration-rotationally resolved emission spectra of HCl (upsilon < or = 6) in the spectral region of 1900-2900 cm(-1) were recorded with a step-scan time-resolved Fourier-transform spectrometer. All vibrational levels show a small low-J component corresponding to approximately 400 K and a major high-J component corresponding to 7100-18,700 K with average rotational energy of 39+/-(3)(11) kJ mol(-1). The vibrational population of HCl is inverted at upsilon = 2, and the average vibrational energy is 86+/-5 kJ mol(-1). Two possible channels of molecular elimination producing HCl + propyne or HCl + allene cannot be distinguished positively based on the observed internal energy distribution of HCl. The observed rotational distributions fit qualitatively with the distributions of both channels obtained with quasiclassical trajectories (QCTs), but the QCT calculations predict negligible populations for states at small J. The observed vibrational distribution agrees satisfactorily with the total QCT distribution obtained as a weighted sum of contributions from both four-center elimination channels. Internal energy distributions of HCl from 2-chloropropene and vinyl chloride are compared.

Quantum Chemical and Kinetics Study of the Thermal Gas Phase Decomposition of 2-Chloropropene

“…The BMK/6-311++G(3df,3pd) optimized structure is shown in the Figure . Previous reported values for the 2-chloropropene geometrical parameters at MP2/6-311G(d,p) and B3LYP/6-31G(d) levels from Parsons et al, B3LYP/6-311++G(3df,3pd) from Bae et al, and B3LYP/6-311++G(d,p) from Chang et al are in good agreement with the present results.…”

“…All values are in good agreement with previous theoretical results. 6,30,31 In addition, mode assignments obtained from the animation of the normal modes and by comparison with species containing similar chemical groups, are included in Tables 2 and B (Supporting Information). Certainly, some of the modes are strongly coupled, and therefore, only approximate assignments are given.…”

A Trajectory-Based Method to Explore Reaction Mechanisms

“…One of the quantities of interest is the product yield, which is usually determined in the experiments. The understanding of the dissociation channels in organic compounds has greatly benefited from the interplay between photolysis experiments and computational studies [70,79,80,81,82,83,84,85,86,87,88,89,90,91,92].…”

A Trajectory-Based Method to Explore Reaction Mechanisms

“…One of the quantities of interest is the product yield, which is usually determined in the experiments. The understanding of the dissociation channels in organic compounds has greatly benefited from the interplay between photolysis experiments and computational studies [70,[82][83][84][85][86][87][88][89][90][91][92][93][94][95].…”