Dr. Martin Kögler and Mr. Bryan Heilala have compiled a review article regarding time-gated Raman spectroscopy. The article introduces the development of time-gated Raman spectroscopy technologies, the working principal of time-gated Raman spectroscopy and some of its applications. The article is a must read for everyone interested in Raman spectroscopy and the latest developments in the area.
The accepted manuscript of the article is available here [link].
Time-gated (TG) Raman spectroscopy has been shown to be an effective technical solution for the major problem of sample- induced fluorescence, masking Raman signal during spectral detection. Technical methods of fluorescence rejection have come a long way from the early implementations of large and expensive laboratory equipment, such as the optical Kerr-gate. Today there are some more affordable small sized options available. These improvements are largely due to advances in the production of spectroscopic and electronic components that further led to the reduction of device complexity and costs. An integral part of TG Raman is the temporally precise synchronization (picosecond range) between the pulsed laser excitation source and the sensitive and fast detector. The detector is able to collect the Raman signal during the short laser pulses while fluorescence emission, which has a longer delay, is rejected during the detector dead-time. TG Raman is also resistant against ambient light as well as thermal missions due to the short measurement duty cycle. In recent years, the focus of ultra-sensitive and fast detectors has been on gated and intensified charge coupled devices (ICCDs) or on CMOS single-photon avalanche diode (SPAD) arrays, which are also suitable for performing TG Raman spectroscopy. SPAD arrays have the advantage of being even more sensitive with better temporal resolution compared to gated CCDs without the necessity of excessive detector cooling. This review aims to provide an overview of TG Raman from early to recent developments, applications and extensions.
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