High resolution synchrotron-based study and analysis of the ν14 band of thiophene

We report a new rotationally-resolved vibrational spectrum of the five-membered heterocycle thiophene (C4H4S). The spectrum was collected with a resolution of 0.00096 cm−1 using the intense, spatially-confined infrared light produced by the Canadian Light Source synchrotron coupled to a Fourier transform spectrometer. The dense rotational structure of the ν14 band of thiophene at 452.4145(6) cm−1 has been analyzed and the ground and excited state parameters have been determined based on the assignment of nearly 3000 c-type transitions corresponding to this ring-puckering mode.