The Study Of Raman Spectrum Of CH₄ By Group Theory

Raman spectrum is an important analytic method of modern laser spectral technique, for the sake of its special advantages(e.g. independent of molecular energy levels), it is applied widely in solution, gases, isotopes, elemental crystal and so on. In the recent years surface-enhanced raman spectrum, resonance raman spectrum technique etc. are developed in succession, and the laser raman spectrum is applied more and more in macromolecule structural analytic field, now raman spectral application involves chemical, physical and biological domain.In this paper analyzing mainly vibrational trait of molecular(include symmetrical trait and spectral properties of molecular vibration) and Raman frequency. Seek the academic explain of molecular in solution which influenced by surroundings. First, introduce classical and quantum explain of Raman effect , in the basis of classical explain applying group theory to constract and analyse 9 normal vibration modes and its spectral properties of CH4. Group theory plays a important role in this paper , using it we can do our best to ease the calculation, from select formula we can also get CH4's spectral properties easily, and compare with result of gaussian soft with computer, and find it correctly. According to analyse we can get 9 normal vibration modes of CH4 are all Raman active, F2 have IR active. Intensity and frequence of CH4 are all influenced notably by solvent effect . In this paper we make use of GF matrix, construst G matrix and F matrix, and put them into equation, then we can obtain vibrational frequency of molecule.As a result of the raman spectrum own merit, causes its widespread application to in the solution sample survey. Therefore the final shallowly discussed the related member the solvent effect which receives in the solution, and attempts with the theory to explain the solution concentration with the raman frequency deviation relations.