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Ultrafast Raman loss spectroscopy (URLS): instrumentation and principle
Author(s) -
Mallick Babita,
Lakhsmanna Adithya,
Umapathy Siva
Publication year - 2011
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.2996
Subject(s) - raman spectroscopy , ultrashort pulse , picosecond , raman scattering , laser , optics , spectroscopy , signal (programming language) , energy (signal processing) , interference (communication) , wavelength , optoelectronics , chemistry , computer science , materials science , physics , telecommunications , channel (broadcasting) , quantum mechanics , programming language
Abstract 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.