Photoacoustic and Photothermal Phenomena

Eds. P. Hess and J. Pelzl, Springer Series in Optical Sciences, v. 58, pp. 316-320, Springer-Verlag, Berlin, 1988.

The Importance of an Adsorbed Liquid Layer for the Enhancement of Photoacoustic Signals

P. Ganguly and Thayumanasamy Somasundaram

Solid State & Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012, INDIA

The enhancement (E) of photoacoustic signals from condensed phases due to the vapours of volatile liquids in the cell has been extensively studied by us. The extent of enhancement (E) is quite different for porous and non-porous solids. The exact mechanism of enhancement is not clear. In the theoretical models given so far, E is attributed to an oscillatory mass transfer to the gas phase. Tam in his review article, also believes that the enhancement is a generalization of the gas evolution process. We have argued that enhancement could either be due to mass transfer or to a more efficient heat transfer to the gas phase. We argue below that the enhancement is crucially dependent on the thickness of the adsorbed liquid layer on the surface of the solid.