Resonance CARS spectroscopy on diacetylene single crystals

An experimental CARS set‐up for resonant solid‐state coherent spectroscopy is described. Resonance CARS spectra of one unsymmetrically (TS/FBS) and two symmetrically (TS6, FBS) substituted diacetylene monomer single crystals, with a low content of polymer, were obtained with this apparatus. Particularly, spectra of the CC and the CC stretching vibrations of the polymer chains, recorded for different pump laser frequencies, were investigated. The occurrence of broad spectral CARS features which are non‐resonant and Stokes shifted relative to other observed CARS lines is discussed.