Raman gas sensing technology: A new horizon?

The question in the title alludes to the importance of comprehending the relevance and manner of operation in the field of gas sensors, which is undeniably one of the most important scientific and economic interests. Despite being superior to several commonly used techniques, such as infrared (IR) spectroscopy, Nondispersive IR (NDIR) and gas chromatography coupled with mass spectrometry (GC-MS), Raman spectroscopy-based gas sensors are yet to be widely explored for real-world applications. Given the weak Raman effect, numerous innovative strategies have emerged to improve its utility in chemical sensing, biological imaging, and material characterization, among other applications. This review covers five important approaches with a high potential for use in Raman-based gas sensors: spontaneous (SRS), stimulated (StRS), coherent anti-Stokes (CARS), surface-enhanced (SERS), and tip-enhanced (TERS) Raman scattering spectroscopy. The initial strategy of this review is to provide the in-depth foundational knowledge necessary for the reader to grasp several types of Raman techniques, their advantages and limitations. This is followed by an overview of current competing technologies and their applications. The remainder of the paper focuses on recent major experimental findings based on the Raman techniques and their practical applications. As a comprehensive introduction to Raman spectroscopy, this review article also serves as a knowledge base for future developments in the field of gas sensors.