An analytical model that incorporates effects of light scattering was developed for dual-beam photothermal deflection spectroscopy. Thermal gradients induced by a modulated excitation beam deflect an optical probe beam which was treated as being of finite dimensions. Mechanisms by which thermal gradients produce refractive index gradients are discussed, with an explicit expression for dn/dT being derived. Experimental studies with suspensions of small latex particles in Nd3+ solutions demonstrated that the model accurately predicts both the shape of the deflection signal and the attenuation of the signal due to light scattering. The absolute magnitude of the observed signal is approximately predicted by theory.
© 1990 Optical Society of America
Original Manuscript: October 24, 1989
Published: October 1, 1990
Jonathan D. Spear, Richard E. Russo, and Robert J. Silva, "Collinear photothermal deflection spectroscopy with light-scattering samples," Appl. Opt. 29, 4225-4234 (1990)