Near-field heterodyne transient grating spectroscopy

The recently developed near-field heterodyne transient grating method is a powerful tool for detecting photochemical dynamics by observing the photo-induced temporal response of the refractive index change. We improved this method such that spectroscopic information could be obtained by using a white light source as a probe light. The spectra of the refractive index change were successfully observed for an anthracene solution, and these spectra were compared with the transient absorption spectra for the same sample. This improvement enables not only assessment of transient dynamics but also qualitative analysis of the photoexcited state.