The application of laser-microwave double and triple resonance to a complex molecular system: Allylamine

Abstract

Information relevant to the infrared spectrum and to the tunneling barrier in highly excited states has been obtained for allylamine from a series of laser-microwave double- and triple-resonance experiments. An extremely large number of double-resonance signals were observed in this molecule with the 10.8-μm, R(8), 13CO 2 laser line. From the extensive use of triple-resonance experiments this laser line was shown to be coincident with infrared transitions in two distinct rotameric forms of allylamine. In the two infrared transition systems analyzed the upper vibrational states proved to be badly perturbed. The use of the triple-resonance technique as an assignment aid under such circumstances is discussed. Rotational constants for two highly excited vibrational states of allylamine were obtained and in one case evidence is presented for a possible large effective lowering of the tunneling barrier. The center frequencies of the two vibrational bands concerned are calculated.