Gas thermometry using Fourier rotational coherent anti-Stokes Raman scattering

Periodic forms of rotational spectra were investigated to extend the application of gas thermometry. Fourier analysis offers a possibility for data reduction and a rapid temperature evaluation procedure. A recursion formula which is a direct consequence of the periodicity of the rotational spectra is presented. Neglected linewidth and laser contributions can be taken into consideration by a simple convolution with the corresponding expressions. The computation of the rotational spectra of nitrogen with 1024 data points reduced to 64 channels is shown. Two procedures, windowing and shifting down the higher frequency components, are included in the method. In the temperature range 300 to 900K the envelopes are well reconstructed. Their maximum position are clearly temperature dependent and allow a simple and rapid temperature evaluations.