赤外振動スペクトルと過酸化水素の分子構造に就て

Abstract

The general description about the infrared vibration spectroscopy was given in this report from both theoretical and experimental view points. For the determination of the molecular structures a number of physical methods, i.e. the X-ray or the electron diffraction method, measurements of the dipole moment, the microwave-spectroscopy, and the observation of ultraviolet, infrared, and Raman spectra etc. are employed. So it may be desired to make clear of the role of the infrared spectroscopy in connection with other methods of the structural investigation of the molecule. In the first part (A) of this report a brief discussion about the relation between the genuine vibrations of a molecule and its symmetry was given. Then, in order to meet the above desire to some extent, the process, by which the molecular structure of the hydrogen peroxide has been decided, as well as the recent observed results of its infrared vibration spectrum were presented. For the genuine vibrations of a molecule their states ΨvK and their energy EK are obtained quantum-mechanically as the solution of the Schrödinger's equation and the numerical values of their frequencies are determined classically from the secular equation based on the Lagrange's equation of motion. In both of these processes the correspondence is formed by the transformation to principal axes which diagonalize the Hamiltonian H or the secular equation with respect to each normal vibration space. On the other hand the irreducible representation in the space of displacements is decided through the symmetry of the molecule by means of the group theory. For the hydrogen peroxide molecule three symmetry types of the molecule, C2, C2h, and C2v were once assumed and it has been considered that the C2 form is correct, referring to various experimental and theoretical results, but the assignments of its vibration spectrum had not been accomplished until Giguère and Taylor assigned their spectra respectively in 1950. The result of Giguère and that of Taylor completely coincide with each other except for the torsional oscillation and the combination band at 2800cm--1, the details of which were discussed in this report. In the second part (B) of this report fundamental informations about the instruments of the infrared vibration spectroscopy, light source absorption cell, spectrometer, and amplifier etc. were given. Especially as an amplifier at our disposal in the present condition, the photocell (or photo barrier layer cell) amplifier consisting of two galvanometers, a simple optical system, a simple electrical circuit, and a photo-cell (or a photo barrier layer cell) was illustrated. In this amplifying system the 1 st galvanometer was used in the resonance condition, which stabilized the measurements with the whole system. This resonance condition was discussed in detail and the recent devices in the feed back circuit of this amplifier was shown.