This article is part of the Journal of Raman Spectroscopy special issue entitled “Proceedings of the 9th European Conference on Nonlinear Optical Spectroscopy (ECONOS), Bremen, Germany, June 21–23, 2010” edited by Peter Radi, PSI, Villigen, Switzerland, and Arnulf Materny, Jacobs University, Bremen, Germany.
Ultrafast Raman loss spectroscopy (URLS): instrumentation and principle†
Article first published online: 14 JUN 2011
Copyright © 2011 John Wiley & Sons, Ltd.
Journal of Raman Spectroscopy
Volume 42, Issue 10, pages 1883–1890, October 2011
How to Cite
Mallick, B., Lakhsmanna, A. and Umapathy, S. (2011), Ultrafast Raman loss spectroscopy (URLS): instrumentation and principle. J. Raman Spectrosc., 42: 1883–1890. doi: 10.1002/jrs.2996
- Issue published online: 24 OCT 2011
- Article first published online: 14 JUN 2011
- Manuscript Accepted: 18 APR 2011
- Manuscript Received: 15 OCT 2010
- ultrafast Raman loss spectroscopy;
- stimulated Raman scattering;
- higher order nonlinear process;
- fluorescence rejection;
- vibrational structure
In this paper, we report on the concept and the design principle of ultrafast Raman loss spectroscopy (URLS) as a structure-elucidating tool. URLS is an analogue of stimulated Raman scattering (SRS) but more sensitive than SRS with better signal-to-noise ratio. It involves the interaction of two laser sources, namely, a picosecond (ps) Raman pump pulse and a white-light (WL) continuum, with a sample, leading to the generation of loss signals on the higher energy (blue) side with respect to the wavelength of the Raman pump unlike the gain signal observed on the lower energy (red) side in SRS. These loss signals are at least 1.5 times more intense than the SRS signals. An experimental study providing an insight into the origin of this extra intensity in URLS as compared to SRS is reported. Furthermore, the very requirement of the experimental protocol for the signal detection to be on the higher energy side by design eliminates the interference from fluorescence, which appears on the red side. Unlike CARS, URLS signals are not precluded by the non-resonant background and, being a self-phase-matched process, URLS is experimentally easier. Copyright © 2011 John Wiley & Sons, Ltd.