IMPULSIVE SOFTENING OF COHERENT PHONONS IN TELLURIUM

We investigate thy dynamics of coherent optical phonons in tellurium a fter high-density excitation with femtosecond laser pulses. The data s how a continuous redshift of the phonon frequency with increasing exci tation density. Experiments with double-pulse excitation prove that th e observed frequency shift is purely electron origin. We demonstrate t hat coherent phonons allow monitoring the pathway to nonthermal laser- induced melting of crystalline materials.