A prototype small photothermal deflection apparatus was constructed on a laboratory bench. Not including excitation laser, data collection computer, and gas pumps, the apparatus fits on a bench space with a footprint of about 10 cm × 10 cm. The apparatus lends itself to miniaturization in future assemblies. The apparatus was tested relative to the conventional laboratory-scale photothermal apparatus. Digital filtering procedures developed in this laboratory were used to collect and analyze the data. Numerical simulation of photothermal signal is performed to accurately predict the heat flow process as sample volumes are scaled down. The results show that increased sensitivity is possible with small apparatus configurations. The prototype apparatus also exhibits high linear response with pulsed irradiance for linear absorbers. Future improvements could include miniaturization with robust configuration that will allow for portable use in trace analysis monitoring of atmospheric pollutants.
Oluwatosin O. Dada and Stephen E. Bialkowski, "A Compact, Pulsed Infrared Laser-Excited Photothermal Deflection Spectrometer," Appl. Spectrosc. 65, 201-205 (2011)