Expand this Topic clickable element to expand a topic
Skip to content
Optica Publishing Group

Time Resolved Frequency Comb Spectroscopy for Studying Gas Phase Free Radical Kinetics

Not Accessible

Your library or personal account may give you access

Abstract

Gas phase free radicals are key intermediates in the chemistry of many important processes, including air pollution, combustion, stratospheric ozone depletion and planetary atmospheres. These trace species exist typically in very low concentrations in both natural settings and laboratory experiments, thus requiring detection methods with high sensitivity, microsecond time resolution, and chemical specificity. Here we present a new approach for time-resolved absorption spectroscopy that exploits advances in the development of frequency comb lasers. This technique, mid-Infrared Time Resolved Frequency Comb Spectroscopy (TRFCS), takes advantage of the large spectral bandwidths of ultrafast lasers and the high sensitivity and spectral resolution of cavity-enhanced absorption spectroscopy. In this approach, the coherent output of a stabilized mode-locked laser generates high resolution frequency combs [1] that are coupled to an external high-finesse cavity. The radiation transmitted through the cavity is dispersed with a Virtually Imaged Phase Array (VIPA) spectrometer [2], permitting simultaneous broad-band detection with high (25 us) time resolution. The cavity encloses a gas flow cell, in which radicals are produced by excimer laser photolysis of precursor gases. Free radicals, transient intermediates and primary reaction products are detected as a function of time. We demonstrate this technique by observing DOCO radicals produced from the 193 nm photolysis of acrylic acid-d1. We have detected simultaneously the depletion of precursor, the formation and loss of DOCO, as well as other primary and secondary products. Current limitations and potential applications will be discussed.

© 2014 Optical Society of America

PDF Article
More Like This
Cavity-Enhanced Mid-IR Optical Frequency Comb Spectroscopy: Enhanced Time and Spectral Resolution

O. H. Heckl, P. B. Changala, B. Spaun, B. J. Bjork, J. Ye, D. Patterson, and J. M. Doyle
STh3M.4 CLEO: Science and Innovations (CLEO:S&I) 2015

Infrared flash kinetic spectroscopy of free radicals

C. B. Moore, R. G. Bergman, I-C. Chen, D. C. Darwin, H. S. Johnston, Y. Guo, E. P. Wasserman, and A. T. Young
THR1 OSA Annual Meeting (FIO) 1988

Time-Resolved Dual Frequency Comb Phase Spectroscopy of Laser-Induced Plasmas

Reagan R. D. Weeks, Yu Zhang, Caroline Lecaplain, Jeremy Yeak, Sivanandan S. Harilal, Mark C. Phillips, and R. Jason Jones
JTh2A.106 CLEO: Applications and Technology (CLEO:A&T) 2019

Select as filters


Select Topics Cancel
© Copyright 2024 | Optica Publishing Group. All Rights Reserved