DYNAMICAL TEST OF DAVYDOV-TYPE SOLITONS IN ACETANILIDE USING A PICOSECOND FREE-ELECTRON LASER

Picosecond infrared excitation experiments on acetanilide, an -helix protein analog, indicate that the anomalous 1650-cm-1 band which appears on cooling of acetanilide crystals persists for at least several microseconds following rapid pulsed heating. The ground-state recovery time is 155 psec, consistent with a conventional mode strongly coupled to the phonon bath. We therefore suggest that the unusual temperature-dependent spectroscopy of acetanilide can be accounted for by slightly nondegenerate hydrogen atom configurations in the crystal. © 1990 The American Physical Society.