Surface photoacoustic wave spectroscopy of thin films

Abstract
Time-resolved detection of the surface acoustic waves (SAW) generated upon relaxation of energy optically absorbed in surface films has been used to measure surface absorption spectra and laser-induced desorption cross sections. This new background-free spectroscopic technique is shown to be highly sensitive to the details of the film/substrate bonding. Minimum detectable molecular surface densities of 2×1011 cm−2 over an area of 10−3 cm2 have been demonstrated for rhodamine-590 dye on a crystal quartz substrate using a pulsed laser source and an edge-bonded SAW detector.
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