A recently proposed technique based on the Fourier transform of the spectrum is applied to the stimulated-emission pumping spectrum of acetylene at -26 500 cm -1 above the vibrational ground state. Correlations on two different time scales ( -3 and -45 ps) were found from analysis of lowresolution (0.3 cm -1 ) and high-resolution (0.05 cm -1 ) spectra, respectively. Additional structure produced dynamic information on a wider (0.5-300 ps) time scale. The results show that acetylene at 26 500 cm " l is in the transition from the regular to the chaotic regime.

International audienceThe vibrational spectrumof acetylene is reported. This is the stimulat emission pumping spectrum obtained by stimulated downward transition from an upper electronic state to the ground electronic surface.Broad band and high resolution spectra were recorded at 25840-27250 wave numbers

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