MicroWave Spectroscopy Laboratory

Main directions of activity Studies of intermolecular interactions Analysis of pressurized water vapor spectra

Analysis of pressurized water vapor spectra

Fig. 1

Fig. 2

It is shown that the evolution of water vapor spectra in the 2500-5000 cm-1 range recorded at 650 K and pressures up to 130 atmospheres (Fig. 1) after subtraction of monomer contribution may be interpreted qualitatively well on the basis of experimental data on water dimer and trimer obtained from cold molecular beams and in He droplets (typical example is shown in Fig. 2). The proposed spectroscopic model considers water vapor as a mixture of monomers, dimers, and trimers at chemical equilibrium. The effect of line mixing is taken into account in the monomer spectrum modeling. Decomposition of the high temperature spectra allowed determining a dimer equilibrium constant that was compared with the previously known values. The contribution of water trimer is assessed. The performed analysis indicates that the number of bound dimers in water vapor is quite large, even at such a high temperature.

See Ref. 3 (2011), Ref. 7 (2013) for more details.

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