Electronic spectroscopy of molecules

Excited Electronic States Electronic Spectroscopy of Molecules... 

The electronic spectra of molecules, even the smallest diatomic molecules, are more complicated than those of atoms because more than one nucleus is present. However, now we can take advantage of molecular symmetry. Just as with vibrational spectroscopy, electronic spectroscopy of molecules uses group-theoretical ideas for simplification. Because all diatomic molecules have either Coov or symmetry, for the present those two point groups will be important. There are also some similarities in electronic spectra and rotational spectra for diatomic molecules, so a review of rotational motions might be useful. 

In the context of electronic spectroscopy of molecules, we represent the system Hamiltonian H as the sum of an electronic ground-state Hamiltonian, Hg, and an... 

Miiller-Dethlefs K (1991) Zero kinetic energy electron spectroscopy of molecules - rotational symmetry selection rules and intensities. Journal of Chemical Physics 95 4821-4839. 

This is the classic work on molecular rotational, vibrational and electronic spectroscopy. It provides a comprehensive coverage of all aspects of infrared and optical spectroscopy of molecules from the traditional viewpoint and, both for perspective and scope, is an invaluable supplement to this section. 

ELECTRONIC SPECTROSCOPY OF DIATOMIC MOLECULES The ground configuration of oxygen is... 

In electronic spectroscopy of polyatomic molecules the system used for labelling vibronic transitions employs N, to indicate a transition in which vibration N is excited with v" quanta in the lower state and v quanta in the upper state. The pure electronic transition is labelled Og. The system is very similar to the rather less often used system for pure vibrational transitions described in Section 6.2.3.1. 

Analysis of Surface Molecular Composition. Information about the molecular composition of the surface or interface may also be of interest. A variety of methods for elucidating the nature of the molecules that exist on a surface or within an interface exist. Techniques based on vibrational spectroscopy of molecules are the most common and include the electron-based method of high resolution electron energy loss spectroscopy (hreels), and the optical methods of ftir and Raman spectroscopy. These tools are tremendously powerful methods of analysis because not only does a molecule possess vibrational modes which are signatures of that molecule, but the energies of molecular vibrations are extremely sensitive to the chemical environment in which a molecule is found. Thus, these methods direcdy provide information about the chemistry of the surface or interface through the vibrations of molecules contained on the surface or within the interface. 

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