Klarenaar B L M, Brehmer F, Welzel S, van der Meiden H J, van de Sanden M C M, Engeln R
Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands.
Dutch Institute for Fundamental Energy Research, 3430 BE Nieuwegein, The Netherlands.
Rev Sci Instrum. 2015 Apr;86(4):046106. doi: 10.1063/1.4918730.
We present a novel approach for filtering Rayleigh scattering and stray light from Raman scattering in a gas discharge, using a volume Bragg grating as a notch filter. For low frequency rotational Raman contributions, it is essential to filter out Rayleigh scattering and stray light at the laser wavelength to be able to measure an undisturbed Raman spectrum. Using the Bragg grating, having an optical density of 3.1 at the central wavelength of 532 nm and a full width at half maximum of 7 cm(-1), we were able to measure a nearly full rotational CO2 spectrum (1.56 cm(-1) peak-to-peak separation). The rotational temperature in a CO2 discharge was determined with an accuracy of 2%.
