IR spectroscopic study of the HCl···O3 molecular complex in liquid argon

Infrared spectra are reported of ozone and HCl dissolved in liquid argon (86-134 K) at concentrations varying from 5×10(-5) to 9×10(-6) M for HCl, and from 1×10(-3) to 5×10(-5) M for ozone. At low concentrations of O3 and of HCl, no spectral features due to O3-HCl complex were found. At higher concentrations (1×10(-3) of ozone vs 5×10(-5)-9×10(-6) of HCl), a new band near 2840 cm(-1) due to the HCl···O3 complex was observed. FWHM of νHCl of the complex is 8 cm(-1). From the temperature dependence of the absorption band intensity, the enthalpy of the complex formation was estimated, ΔH°=4.7±0.4 kJ mole(-1). The optimized geometry of the cis-HCl···O3 complex and a value of 6.3 kJ mole(-1) for its binding energy were determined by ab initio calculations.