ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
An UV multipass optical absorption method to increase the sensitivity for radical species detection has been developed for high temperature chemical kinetics experiments in a shock tube. The specific illustration is for OH radicals in the reflected shock wave regime. With a resonance lamp source, 12 optical passes were found to give a sufficient signal-to-noise ratio for a large range of [OH]. Two different calibration procedures using the reaction systems H2/O2 and C2H5I/NO2 were used, and a curve of growth was determined. The measured absorbance (ABS), was found to be dependent on both temperature and [OH]. The results can be expressed in a modified Beer's law form as,(ABS)=9.49×10−12T−0.5281[OH]0.8736.Using this curve of growth, the absorbance data from the above kinetics experiments were converted to concentration profiles. These were fully modeled with previously established mechanisms, giving excellent fits. The multipass method is compared to earlier systems that used both resonance lamp and laser absorption sources, and the increase in sensitivity is found to be substantial due primarily to the increased path length. This increased sensitivity inhibits the effects of any possible secondary chemistry thereby allowing chemically isolated experiments on OH + molecules to be performed at high temperatures. © 1995 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1145302
