Picosecond infrared studies of H− local modes in LaF3

Three-beam normalised pump–probe measurements for the Z-localised vibrational mode of H− in LaF3 yield a 10 K population decay time (T1) of 49 ps. The temperature decrease of this T1 time is fitted to two-phonon anharmonic decay together with one-phonon absorption to the 351 cm−1 higher (X, Y)-mode. Two-pulse vibrational echo measurements yield a homogeneous line width of 0.3 cm−1.