Rodrigues Jocelino, Weller Lee, De Domenico Francesca, Hochgreb Simone
Department of Engineering, University of Cambridge, Cambridge, CB2 1PZ, UK.
Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS, Delft, The Netherlands.
Sci Rep. 2023 Aug 1;13(1):12472. doi: 10.1038/s41598-023-37649-1.
A high-frequency (1.5 kHz) spontaneous Raman spectroscopy measurement technique is developed and applied to measure external fluctuations generated in the local concentration of an isothermal binary gas mixture of methane and air. Raman excitation is provided by a high-frequency laser at 527 nm in dual-pulsed mode. The Stokes Raman signal is collected using an EMCCD camera coupled to a high-frequency intensifier as a shutter. The emitted signal is collected over the 596-627 nm wavelength range, which allows for the simultaneous tracking of methane and nitrogen Stokes Q-branch mode signals. Calibration curves are initially obtained for each species ([Formula: see text] and [Formula: see text]) based on steady-state concentrations, and further corrected during use to detect local unsteady mixture fluctuations at gas pulsation frequencies up to 250 Hz. The main novelty is the demonstration of Raman spectroscopy for the simultaneous multispecies measurement of unsteady concentrations of gas-phase methane and air mixtures using a laser beam with a high-repetition rate, low energy per pulse, combined with a high-frequency intensifier and a single camera.
开发了一种高频（1.5kHz）自发拉曼光谱测量技术，并将其应用于测量甲烷和空气等温二元气体混合物局部浓度产生的外部波动。拉曼激发由527nm的高频激光以双脉冲模式提供。使用与高频增强器耦合的EMCCD相机作为快门收集斯托克斯拉曼信号。在596 - 627nm波长范围内收集发射信号，这允许同时跟踪甲烷和氮的斯托克斯Q分支模式信号。最初基于稳态浓度为每个物种（[公式：见正文]和[公式：见正文]）获得校准曲线，并在使用过程中进一步校正，以检测高达250Hz的气体脉动频率下的局部非稳态混合物波动。主要创新点在于展示了使用具有高重复率、每脉冲低能量的激光束，结合高频增强器和单个相机，对气相甲烷和空气混合物的非稳态浓度进行同时多物种测量的拉曼光谱技术。
