Observation of Light-Induced Reactions of Olefin–Ozone Complexes in Cryogenic Matrices Using Fourier-Transform Infrared Spectroscopy

Fumiyuki Ito

doi:10.3390/photochem2010012

Abstract

Each olefin (ethylene, trans-1,3-butadiene, isoprene, dimethyl butadiene (DMB)) and ozone molecules were codeposited on a CsI window at cryogenic temperature, and the products of photolysis with ultraviolet–visible light were observed using Fourier-transform infrared spectroscopy. The products of the C2H4–O3 system could be assigned to glyoxal (CHO–CHO), ethylene oxide (c–C2H4O), CO, and CO2. The formation of CHO–CHO and c–C2H4 and the absence of H2CO and HCOOH indicated that the main reaction channels did not involve C–C bond breaking. Based on this simple scheme, the photoproducts of different olefin–O3 systems were assigned, and the vibrational features predicted by density functional theory calculations were compared with the observed spectra. Regarding butadiene, spectral matches between the observations and calculations seemed reasonable, while assignments for isoprene ambiguities of and DMB remain, mainly because of the limited availability of authentic sample spectra.

Highlights

The products of oxidation of volatile organic compounds (VOCs) contribute to secondary organic aerosols (SOAs) in the atmosphere and influence climate and local air quality [1]
The purpose of this study is to investigate the light-induced reactions of olefin–O3 systems spectroscopically in a cryogenic noble gas matrix to minimize the effect of thermal excitation of reactants
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Summary

Introduction

The products of oxidation of volatile organic compounds (VOCs) contribute to secondary organic aerosols (SOAs) in the atmosphere and influence climate and local air quality [1] In this respect, unsaturated VOCs such as ethylene (C2H4) [2] and isoprene (C5H8) [3], have been intensively investigated. Many of the gas phase studies have been focused on ozonolysis in dark conditions, and have been done at moderate temperatures [8,9,10,11,12,13]. Quite recently, these reactions have been under further scrutiny at lower temperature by using new experimental techniques [14,15]. Ault and coworkers have performed systematic studies on these systems [24,25,26,27], and we will refer to them in comparison with this study

Objectives

Methods

Results