Acoustic behaviour of amorphous selenium

The attenuation of longitudinal sound waves in amorphous selenium has been measured at frequencies of 15 and 25 MHz and in the range of temperature between 10 and 310 K. It is shown that absorption exhibits a minimum around Tτ150 K, while a pronounced maximum takes place around 30 K. Such a behaviour is briefly discussed in the frame of acoustic properties of amorphous material below the glass temperature. It is shown that the experimental results can be described, almost qualitatively, in terms of a recently proposed theoretical model involving a stochastic resonance that seems to be characteristic of the disordered systems.