A liquid helium cryostat for the study of pressure effects on hole burned spectra of hyperquenched glassy films

A liquid helium cryostat that allows for thermospray deposition of samples in vacuum and subsequent pressure dependent studies up to 150 atm is described. Performance of the cryostat is illustrated by study of the pressure-induced shifts and broadening of holes burned in the lowest energy absorption band of aluminum phthalocyanine tetrasulfonate in hyperquenched glassy water. The hole widths exhibit an unusual dependence upon the pressure at which they are burned and also a linear frequency shift which depends upon the sign of the pressure change. (C) 1999 American Institute of Physics. [S0034-6748(99)00705-4].