Room Temperature Gas Phase Equilibrium Constants of the Methanol Dimer, Trimer, and Tetramer.

We have detected the methanol dimer, trimer, and tetramer at equilibrium conditions at room temperature in the gas phase using direct absorption Fourier transform infrared spectroscopy. The infrared intensity of the OH-stretching transitions are enhanced upon hydrogen bonding and are increasingly red-shifted with increasing cluster size, facilitating identification and quantification of the various clusters. We calculate the intensities of the bound OH-stretches, OH, for all clusters with a range of reduced dimensional vibrational models with different levels of electronic structure theory.

Effect of Temperature on the OH-Stretching Bands of the Methanol Dimer.

We present a conceptually simple model for understanding the significant spectral changes that occur with the temperature in the infrared spectra of hydrogen-bound complexes. We have measured room-temperature spectra of the methanol dimer and two deuterated isotopologues in the OH(D)-stretching region. We correctly predict spectral changes observed in the gas phase for the bound OH stretch in the methanol dimer from jet-cooled to room temperature and corroborate this with experimental and theoretical results for deuterated isotopologues.

Gas-Phase Room-Temperature Detection of the -Butyl Hydroperoxide Dimer.

We have detected the -butyl hydroperoxide dimer, (-BuOOH), in the gas phase at room temperature using conventional FTIR techniques. The dimer is identified by an asymmetric absorbance band assigned to the fundamental hydrogen-bound OH-stretch. The weighted band maximum of the dimer OH-stretch is located at ∼3452 cm, red-shifted by ∼145 cm from the monomer OH-stretching band.