Transient lens spectroscopy in a fast timescale

Using the thermal lens experimental configuration, many types of fast molec ular dynamics besides the density variation (the normal thermal lens signal ) are reflected by the lens signal. Various transient lens techniques in a fast timescale are reviewed. By using the population lens signal, excited s tate dynamics can be studied with a probe light which has less restricted w avelength range over a wide timescale from a few femotoseconds to seconds. From the optical Kerr lens signal, molecular reorientational dynamics in so lution can be revealed. The temporal development of the temperature lens si gnal provides unique information such as the thermalization time after nonr adiative transition from the excited state, which is usually very difficult to determine by other spectroscopies. Identification of the lens component s and the advantages of the time-resolved transient lens method are discuss ed.