Photodissociation of Acetyl Chloride Detected by Time-resolved Fourier Transform Infrared Spectroscopy
Date Issued
2009
Date
2009
Author(s)
Liu, Yu-Ting
Abstract
In one-photon dissociation of acetyl chloride CH3COCl at 248 nm, time-resolved Fourier-transform Infrared emission spectroscopy is used to detect the primary fragments of HCl, CO, and CH2 in the presence of Ar or O2. Emission from both CO and HCl was observed. Spectrum analyses are carried out for HCl and CO fragments to yield the information of population distribution and energies of rotational and vibrational levels. Assignments of the HCl spectra are shown vibrational level is populated up to 3 and rotational level J up to ~10. For CO product, the rotational level J is up to ~30 and vibrational level is up to 4. Nascent populations and energies are also obtained by extrapolated the temperatures to t=0 for both HCl and CO fragments. In previous works, the photodissociation of acetyl chloride is dominant by the C-Cl bond cleavage in collision-free gas phase and exclusive HCl elimination channel from the HCl．CH2CO complex with a T-shaped structure is confirmed in condensed phase. It is for the first time to find that the Ar or O2 addition in the gas phase photodissociation of CH3COCl may facilitate collision-induced internal conversion process with which the HCl and CO elimination are associated. In this study, the HCl and CO fragments are confirmed directly by the particular infrared emission observation; on the other hand, the CO2 emission is postulated by the third photofragment CH2 reacted with O2. The observed fragments are anticipated to result from a dissociation channel via a converted three-body photodissociation mechanism, which is unfounded ever before.
Subjects
step-scan Fourier transform spectroscopy
time-resolved spectra
infrared emission
acetyl chloride
photodissociation
CH3COCl
HCl
CO
rotational population
vibrational population
Type
thesis
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