Cell design for picosecond time-resolved infrared spectroscopy in high-pressure liquids and supercritical fluids.

The design of a new high-pressure infrared (IR) cell for carrying out picosecond time-resolved infrared (ps-TRIR) spectroscopy in supercritical fluids is described. We have employed thin (2 mm) MgF(2) windows in order to overcome possible undesirable nonlinear optical effects caused by the extremely high peak powers of ultrashort ultraviolet (UV)/visible pulses. The design of our cell allows for the study of systems at pressures of up to 5500 psi at temperatures of up to approximately 50 degrees C. The MgF(2) windows enable the excitation of samples with both UV and visible light pulses and these windows are transparent across much of the mid-infrared region. We have demonstrated the use of this cell by examining the photochemistry of Fe(CO)(5) in supercritical Kr (sc Kr).