Mass‐correlated rotational Raman spectra and the structure of furan

We present mass‐correlated rotational alignment spectroscopy and the first high‐resolution rotational Raman spectra for furan. Spectra were measured with a spectral range up to 0.5 THz and a resolution down to 1.6 MHz. Spectra for 13C and 18O isotopologues were observed in their corresponding mass channels at natural abundance. Based on our data and literature constants, we performed a purely experimental structure analysis for the effective and equilibrium structures of furan. The results highlight the utility of CRASY to obtain rare isotopologue spectra without isotopically enriched samples. Mass‐correlated rotational Raman spectra were observed for furan and its 13C and 18O isotopologues at natural abundance. Measurements were performed in a mass spectrometer, using time‐delayed laser pulses for impulsive excitation and subsequent photoionization of a rotational wave packet. A rotational resolution up to 1.6 MHz was achieved by scanning an extended pump‐probe delay range up to 1 μs. The data were used to perform a purely experimental structure analysis of furan.