We present experimental demonstrations using a broadly tunable external cavity quantum cascade laser (ECQCL) to perform Reflection-Absorption InfraRed Spectroscopy (RAIRS) of thin layers and residues on surfaces. The ECQCL compliance voltage was used to measure fluctuations in the ECQCL output power and improve the performance of the RAIRS measurements. Absorption spectra from self-assembled monolayers of a fluorinated alkane thiol and a thiol carboxylic acid were measured and compared with FTIR measurements. RAIRS spectra of the explosive compounds PETN, RDX, and tetryl deposited on gold substrates were also measured. Rapid measurement times and low noise were demonstrated, with <1E-3 absorbance noise for a 10 second measurement time.

Date Published: 4 February 2013
PDF: 13 pages
Proc. SPIE 8631, Quantum Sensing and Nanophotonic Devices X, 86310C (4 February 2013); doi: 10.1117/12.2002849

Published in SPIE Proceedings Vol. 8631:
Quantum Sensing and Nanophotonic Devices X
Manijeh Razeghi, Editor(s)