VIBRATIONAL AND ROTATIONAL SPECTRA
1990; Elsevier BV; Linguagem: Inglês
10.1016/b978-0-08-091740-5.50004-1
AutoresNorman B. Colthup, Lawrence H. Daly, Stephen E. Wiberley,
Tópico(s)Various Chemistry Research Topics
ResumoThe energy of a molecule consists partly of translational energy, rotational energy, vibrational energy, and electronic energy. Electronic energy transitions give rise to the absorption or emission in the ultraviolet and the visible regions of the electromagnetic spectrum. Pure rotation gives rise to the absorption in the microwave region or the far infrared. Molecular vibrations give rise to the absorption bands throughout most of the infrared region of the spectrum. This chapter focuses on vibrational and rotational spectra and discusses how molecular vibrations and rotations interact with radiation to create the infrared and Raman spectra. The vibrational and the rotational frequencies of molecules can be studied by Raman spectroscopy and by infrared spectroscopy. While they are related to each other, the two types of spectra are not exact duplicates and each has its individual strong points. In Raman spectroscopy, only the wave number is used. Infrared and Raman spectrum both involve vibrational and rotational energy levels; they are not duplicates of each other but rather complement each other. This is because the intensity of the spectral band depends on how effectively the photon energy is transferred to the molecule.
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