OH‐thermometry using laser polarization spectroscopy and laser‐induced fluorescence spectroscopy in the OH A‐X (1,0) band

Laser‐induced fluorescence (LIF) and polarization spectroscopy (PS) is used for OH‐thermometry utilizing the off‐diagonal A‐X (1,0) band. Both techniques are used simultaneously in order to allow a comparison of the results. For deriving temperature information from the spectra, three methods are employed: (1) a contour fit method comparing experimental and calculated spectra, (2) spectral fitting of a single highly resolved spectral line and (3) a two‐line intensity ratio approach. In general, both spectroscopic techniques gave similar results. The high‐resolution approach (2) did not deliver reasonable results in our experiments. The most accurate but also most time consuming method was the contour fit (1). For future two‐dimensional temperature measurements, the 2‐line‐method (3) was identified to be the method of choice. The present study contains, to the best of our knowledge, the first polarization spectroscopic study in the A‐X (1,0) band of OH.