Conformational Interchange in the 10 µm and 3µm Infrared Spectra of Propargyl Amine

The propargyl amine spectrum was observed using an electric resonance optothermal spectrometer coupled to a CO2 laser-microwave sideband system for measurement of 10 µm spectra and to a color center laser for 3 µm spectra. Three bands were recorded in the 10 µm region; all were characterized by doubling of the transitions with a 3:1 intensity ratio, which is attributed to a torsion-inversion tunneling motion interchanging the two amine hydrogen atoms. The 3 µm band was greatly fractionated due to IVR. From double resonance experiments, each IVR component could be associated with one of the two tunneling states observed in the 10 µm spectrum.