Pulse-Laser Infrared Photothermal Spectrometry of Condensed-Phase Aerosols Based on Photothermal Deflection Spectroscopy

In this chapter, 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 x 10 cm. This is a prototype apparatus that will be miniaturized 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. The main result is that the small apparatus performs about the same as the larger laboratory-sized one in terms of sensitivity. The apparatus also exhibits a linear response for linear absorbers indicating a high dynamic range. Future improvements will include miniaturization and rugged construction. This will allow for portable use. Data processing will be adapted to modern operating systems. An electronics module containing the timing and data collection electronics will also be prototyped.