Sound propagation in a highly damped Mo_6S_3I_6 nanowire network measured by femtosecond pump-probe spectroscopy

摘要

Using femtosecond pump-probe spectroscopy we have measured the propagation of sound in a randomly formed Mo_6S_3I_6 nanowire network for the first time. The pump-probe technique allows us to measure the reflection of an optical pulse from a propagating acoustical disturbance in spite of very high sound damping in the rather porous network medium. We use a range of different laser wavelengths from 0.7 to 2.4 μm and a measurement of the refractive index n, to obtain a value of sound velocity v = 1630±160 m/s.