Femtosecond pump and probe spectroscopy in Bi under high pressure

We have observed coherent phonons and electronic response in bismuth single crystals under hydrostatic pressure up to 3 GPa at room temperature. Both signals show drastic changes at 2.5 GPa where phase transition occurs. The phonon frequency decreases from 2.9 THz to 2.5 THz and the initial phase of the phonon shifts about 180 degrees at this pressure. The electronic response shows anomalous behaviour above phase transition pressure. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.