Determination of Optodynamic Excitation Mechanism Following Laser Pulse Absorption in CuSO4 Solution

Darja Horvat,a Mira Terzić,b and Janez Možina a

a Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, 1000 Ljubljana, Slovenia

b Faculty of Science, University of Novi Sad, Trg Dositeja Obradovića 4, 21000 Novi Sad,Serbia and Montenegro

Optodynamic phenomena in aqueous solutions of CuSO4 were experimentally investigated for two different concentrations (0.025 M and 0.05 M). The solutions were irradiated with a pulsed Nd:YAG laser operating at 1064 nm, with pulse energy varied from 180 to 760 mJ. Optodynamic sources were formed at different distances from the liquid – air boundary inside the liquid and in the air. The propagating optodynamic waves were detected with a laser beam deflection probe inside the liquid. The possibility of identification of different optodynamic excitation mechanisms was investigated. Spatial nonhomogenity of the laser beam profile influences the absorption process at and near the liquid – air boundary. As a consequence of this influence the shape and characteristics of the optodynamic source were considered. It was found out that optodynamic amplitude analysis can be used to assess the light power density at which the transition from linear to nonlinear excitation regime occurs.

Key words: Key words: optodynamics, optodynamic generation mechanism, ultrasonic waveform, photoacoustic spectroscopy