NH3inversion in condensed media. Static, dynamic, and inhomogeneous environmental effects on the internal tunneling

摘要

The ngr;2umbrella mode of vibrationndash;inversion of ammonia trapped in condensed media exhibits typical tunneling slowhyphen;down due to the statics, the dynamics, and the inhomogeneity of the ambiant solid. The reduction of the level splitting of the ngr;2mode of ammonia from 37.6 cmminus;1in gas to 24 cmminus;1in argon, to 22 cmminus;1in xenon, and to 1.65 cmminus;1in nitrogen is interpreted in terms of the statical and dynamical influence of the matrix. In argon, the static environment accounts for 92percnt; of the tunneling slowhyphen;down. In xenon, 45percnt; of the effect is due to the dynamical inertia of the surrounding matrix. In nitrogen, the Franckndash;Condon dynamical influence represents about 70percnt; of the effect. These results are in good agreement with experimental data and are consistent with results observed in other physical cases (phase transitions, superconductors, proton transfer). It is also shown that the environmental inhomogeneity due to the presence of other ammonia molecules cannot be neglected for the determination of the inversion level splitting in nitrogen matrix, even for high dilution (cle;1/20thinsp;000) of ammonia molecules in the solid.