Evaporatively cooled M ⁺(H ₂O)Ar cluster ions: Infrared spectroscopy and internal energy simulations

The measurement of rotationally resolved infrared (IR) spectra of M ⁺(H ₂O)Ar cluster ions, for M is any alkali-metal, in the O-H stretch region done in a triple-quadrupole mass spectrometer was analyzed. The analysis of the spectra yielded O-H stretch vibrational band origins and relative IR intensities of the symmetric and asymmetric modes. The A-rotational constants obtained from the rotational structure were also discussed. The RRKM calculations and the evaporative ensemble formalism were used for the simulation of the internal energies and temperatures of the cluster ions for Na and K. The results indicate the possibility of accurately modeling of argon-bearing cluster ions.