It is proposed to make pump-probe picosecond measurements on molecular defects in crystalline, polymeric and glassy solids throughout the infrared region of the spectrum with an infrared- tunable picosecond laser system. The ability to tune to infrared vibrational transitions will make possible the first systematic investigation of energy transfer processes while the entire solid remains in the electronic ground state. Funds are requested for the Cornell Far Infrared Laboratory to purchase a laser system which generates high intensity infrared pulses with wavelengths tunable from 1.5 microns to 8 microns. This system consists of a high-energy mod-locked neodymium yttrium aluminum garnet (Nd:YAG) laser, part of whose output is doubled in frequency and used to pump a set of picosecond dye laser stages. Infrared radiation is then generated by mixing the dye laser output with the fundamental of the Nd:YAG laser in a nonlinear crystal.
