Rotationally resolved infrared–vacuum ultraviolet–pulsed field ionization–photoelectron depletion method for infrared spectroscopic studies of neutral molecules

The comparison of rotationally resolved infrared–vacuum ultraviolet–pulsed field ionization–photoelectron (IR–VUV–PFI–PE) depletion and IR–VUV–photoion measurements of C2H4 has illustrated the difference of these two methods and the rotational nature of the IR–VUV–PFI–PE depletion method. The IR–VUV–photoion spectra of trans-2-butene in the region 2910–3000 cm−1 observed at different delays between the IR and VUV lasers are also presented to show that the IR–VUV–PI method is potentially useful for the study of intramolecular vibrational redistributions (IVRs). For short IVR lifetimes of vibrationally excited polyatomic neutrals, the IR–VUV–PFI–PE depletion method can serve as an alternative of the IR–VUV–PI scheme for rotationally resolved IR spectroscopy measurements.