What is FSRS?

“Femtosecond stimulated Raman spectroscopy (FSRS) is an ultrafast nonlinear optical technique that provides vibrational structural information with high temporal (sub-50 fs) precision and high spectral (sub-10 cm−1) resolution. Since the first full demonstration of its capabilities approximately 15 years ago, FSRS has evolved into a mature technique giving deep insights into chemical and biochemical reaction dynamics that would be inaccessible with any other technique. It is now being routinely applied to virtually all possible photochemical reactions and systems spanning from single molecules in solution to thin-films, bulk crystals and macromolecular proteins.

Traditionally, FSRS is a three-pulse experiment. An actinic pump pulse excites the molecule in the usual way and initiates the photochemical reaction. The instantaneous structure of the molecule, represented by its Raman spectrum, is then read out at various time delays by a sequence of a narrowband Raman pump pulse and a broadband probe pulse. The latter creates a macroscopic polarization with high time precision giving rise to a free induction decay, which is measured with high energy resolution by a dispersed detection system.” (Dietze and Mathies, in preparation)

If you are interested in the technique and its technology, I recommend the following two papers as a starting point:

• McCamant et al., Appl. Spectrosc. 57, 1317 (2003).
• McCamant et al., Rev. Sci. Instrum. 75, 4971 (2004).