IR spectra of the CH3 stretching region of methylamine monomer, dimer and trimer in helium nanodroplets

We report the infrared spectra of the CH 3 stretching region in methylamine monomer and its clusters in superfluid helium nanodroplets. Using mass-selective IR spectroscopy in combination with band intensities as the function of methylamine pressure, we were able to assign the vibrations of the (methylamine) 1-3 clusters. In addition to the fundamental vibrations, overtone and combination bands are observed. As an example, in the high-resolution spectrum of methylamine monomer, 15 spectral features were observed, compared to 9 features reported in the literature. All the bands could be assigned based on recent anharmonic calculations. • High-resolution infrared spectra of methylamine monomer, dimer and trimer. • Observation and assignments of new overtones and combination bands. • Assignments of all clusters by comparing predicted spectra reported recently.