Vibration of molecular bonds

The vibrations of molecular bonds provide insight into bonding and stmcture. This information can be obtained by infrared spectroscopy (IRS), laser Raman spectroscopy, or electron energy loss spectroscopy (EELS). IRS and EELS have provided a wealth of data about the stmcture of catalysts and the bonding of adsorbates. IRS has also been used under reaction conditions to follow the dynamics of adsorbed reactants, intermediates, and products. Raman spectroscopy has provided exciting information about the precursors involved in the synthesis of catalysts and the stmcture of adsorbates present on catalyst and electrode surfaces. 

The harmonic oscillator is an important system in the study of physical phenomena in both classical and quantum mechanics. Classically, the harmonic oscillator describes the mechanical behavior of a spring and, by analogy, other phenomena such as the oscillations of charge flow in an electric circuit, the vibrations of sound-wave and light-wave generators, and oscillatory chemical reactions. The quantum-mechanical treatment of the harmonic oscillator may be applied to the vibrations of molecular bonds and has many other applications in quantum physics and held theory. 

The Fourier-transform infrared system (FTIR) is a well-known spectroscopic technique based on the absorption of infrared photons that excite vibrations of molecular bonds. Molecules such as UsOg, UO2, UO3, Th02, have characteristic absorption bands in the infrared region that can be used like a fingerprint to detect their respective presence. FTIR radiometry has become a relatively mature and reliable method for the identification and measurement of chemicals emitted from stacks and its potential for passive standoff detection of nuclear material is under investigation (Puckrin and Theriault 2006). 

Finally, one interesting way in which electrical effects are interlaced with vibrational effects is in hydrogen bonding. Intermolecular electrical interaction appears to be a dominant factor in understanding red shifts and transition moment enhancements in intramolecular vibrations of hydrogen-bonded molecules [90, 119, 120]. Undoubtedly, there will be other types of molecular problems that are revealed to be dependent on electrical features. The capability for ab initio study of electrical properties paves the way for this to happen. 

When infrared radiation of successive frequencies (or wavelengths) is incident on a molecule, some of the radiation frequencies correspond to characteristic frequencies of the molecule, and under such natural resonant conditions energy can be exchanged from one system to another if a coupling mechanism is available. The coupling mechanism in this case is the change in electric dipole moment caused by the vibration of a bond. The scanning of a molecular sample with successive infrared frequencies shows frequency values for which the radiation is absorbed, and these values correspond qualitatively to mechanical vibration frequencies of the molecule. The infrared spectrum is an analysis of the molecular vibrations. 

The last term represents absorption losses due to impurities and intrinsic UV (electronic) and IR (vibrational) absorption. Absorption due to molecular vibrations in the IR tends to occur in bands over which the frequency of light resonates with the vibrational frequency of molecular bonds. For SiO , this does not become significant until wavelengths are longer than about 1.5... 

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