CAVITY-ENHANCED ABSORPTION SPECTROSCOPY: Mid-IR QCL with shock tube measures CO concentrations

摘要

Researchers at Stanford University (Palo Alto, CA) have given a boost to the venerable shock-tube approach to studying high-temperature chemical reactions by using a mid-infrared quantum-cascade laser (QCL) incorporated into a cavity-enhanced absorption spectroscopy (CEAS) instrument for detection of carbon monoxide (CO). The in situ measurements of CO in the shock tube were made to a time resolution of 10 μs. A shock tube contains a low-pressure chamber filled with a gas precursor mixture to be analyzed, separated by a diaphragm from a second, high-pressure chamber. With enough pressure, the diaphragm burst, forming a shock wave that travels rapidly through the precursor, compressing and accelerating it; the shock wave then bounces off the end of the chamber, stopping, compressing, and heating the precursor again.