Study of the spectral characteristics of the photoacoustic effect in HgI2 crystals at different levels of vibrational strain amplitude

An experimental study is reported of the effect of light on the acoustic ch aracteristics of a HgI2 crystal at two levels of the vibrational strain amp litude, one of which lies in the amplitude-independent (AI), and the other in the amplitude-dependent (AD) ultrasound absorption (UA). These studies l ed to the spectral parameters of the photoacoustic effect (PAE) both for th e decrement and for Young's modulus of the HgI2 crystal. It was shown that the PAE spectra of a sample exposed to high-amplitude ultrasound undergo, i n some cases, substantial changes compared to those for low amplitudes (the AIUA region). These changes may be related both to the diffusion of photos ensitive dislocation-pinning centers (photocarrier trapping centers) and to their creation-annihilation induced by light and high amplitudes in the AD UA region. It is shown that the excitation of electron-hole pairs captured by vacancies or iodine or mercury interstices can also noticeably affect th e dislocation mobility in HgI2. (C) 2000 MAIK "Nauka/Interperiodica".