Abstract
We present calculated intensity distributions in torsional, rotational, and torsional-rotational Raman lines in spectra of hydrogen peroxide. Ab initio calculations of polarizability tensor components as functions of internal rotation angle were carried out in the HF/6-311G approximation. It is shown that the structure and transformational properties of the polarizability tensor components of hydrogen peroxide in extended molecular symmetry group G4(EM) permit formation of purely rotational and torsional and rotational-torsional Raman spectra. Common expressions to calculate Raman line intensities governed by torsional and rotational motions of the non-rigid symmetric top molecule are obtained. The torsional components of the line intensities have been calculated by estimating the appropriate matrix elements. The contribution of rotational components has been calculated using the 3j-symbols technique.
Highlights
The analysis, calculation, and interpretation of torsional-vibrational IR spectra of hydrogen peroxide, the simplest member of the class of non-rigid molecules, have been the subject of numerous experimental and theoretical studies [1,2,3,4,5]
Recent research has shown [6] that the frequencies and intensities of the H2O2 torsional-rotational IR spectrum can be successfully calculated because the dependences of the molecular dipole moment components in a fixed molecular coordinate system on the internal rotation angle are known
Calculations were performed for torsion angle γ in the range 0–180o in steps of 10o with fixed dihedral angle and molecular geometry optimized over all other parameters
Summary
We present calculated intensity distributions in torsional, rotational, and torsional-rotational Raman lines in spectra of hydrogen peroxide. Ab initio calculations of polarizability tensor components as functions of internal rotation angle were carried out in the HF/6-311G approximation. It is shown that the structure and transformational properties of the polarizability tensor components of hydrogen peroxide in extended molecular symmetry group G4(EM) permit formation of purely rotational and torsional and rotational-torsional Raman spectra. Common expressions to calculate Raman line intensities governed by torsional and rotational motions of the non-rigid symmetric top molecule are obtained. The torsional components of the line intensities have been calculated by estimating the appropriate matrix elements. The contribution of rotational components has been calculated using the 3j-symbols technique
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