engleski

Prospect of temperature determination using degenerate four-wave mixing with sub-20 fs pulses

Femtosecond time resolved degenerate four-wave mixing (DFWM) spectroscopy with ultrashort laser pulses was applied to probe pure rotational Raman transitions in the H$_2$ molecule. Owing to the broad bandwidth of the sub-20 fs pulse several pure rotational Stokes and anti-Stokes transitions are simultaneously excited with the same pulse making the experiment interesting for thermometry in combustion processes. Simulations of the DFWM signal show exactly how the change in population distribution due to changes in temperature influences the shape of the transients and the corresponding Fourier transform (FFT). The influence of the pulse duration is also investigated. The relative peak intensities in FFT spectra are employed for temperature determination. First measurements at room temperature show good agreement with the theoretical predictions.

femtosecond spectroscopy; hydrogen; four-wave mixing; temperature determination

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