Detection of Methane with High Spatial Resolution with Photothermal Deflection Spectroscopy

We demonstrate the use of photothermal deflection spectroscopy for detection and measurement of methane with very high spatial resolution. A high spatial resolution may be important for some applications, and other techniques in current use do not provide this resolution. To the best of our knowledge, this is the first application of photothermal spectroscopy to methane detection. We have succeeded in detecting a signal even from a very weak combination-overtone band of methane in the visible region of the spectrum. If used in conjunction with a strongly absorbing fundamental band, the technique is capable of yielding high sensitivity along with very high spatial and temporal resolutions.