Sub-nanosecond laser ultrasonics in micro-layers of liquids

Nikolay Chigarev (1) , Vincent Tournat (1) , Vitali Goussev

1 LAUM - Laboratoire d'Acoustique de l'Université du Mans

The study of the acoustic properties of liquid micro-layers is necessary for biological and micro-technological applications. Laser ultrasonic technique on the basis of sub-nanosecond pump laser [Appl. Phys. Lett. 93, 181905 (2008)] provides unique opportunity for the contactless and non-destructive evaluation of the materials at spatial scales from micrometer to few tens of micrometers. Here we report on the application of this technique for the study of acoustic properties of liquid layers of micrometric thickness confined between two parallel glass plates. The acoustic pulses are excited by the absorption of a pump laser pulse in a nanometric aluminium film deposited on one of the plates and are detected by photo-deflection technique. Transient photo-acoustic signals are measured at different separation distances between pump and probe beam spots. Then, this information is used for plotting the dispersion curves [Phys. Rev. Lett. 100, 158003 (2008)]. Numerous acoustic modes have been detected and their physical nature has been explained with the help of the developed theoretical models. The opportunities to extract from the evaluated dispersion curves the information on the elastic and inelastic properties of the liquids and to characterize the adhesion of liquid layer to the surrounding solid are discussed.

Mots clés: Laser ultrasonics

Domaines: Acoustique [physics.class-ph]

Nikolay Chigarev, Vincent Tournat, Vitali Goussev. Sub-nanosecond laser ultrasonics in micro-layers of liquids. Acoustics 2012, Apr 2012, Nantes, France. ⟨hal-00810593⟩