Fundamentals of Electronic Spectroscopy

Abstract

The basic principles of electronic spectroscopy of atoms and molecules in the gas phase are presented. In the first part, the elementary concepts necessary to describe the electronic structure of atoms, diatomic molecules, and polyatomic molecules are introduced in a systematic manner, with an effort to classify the different interactions (electrostatic, spin–orbit, hyperfine) and types of motions (electronic, vibrational, rotational), which determine the energy level structures. In the second part, electronic transitions are discussed, with their spin‐rovibrational structures. Examples ranging from the simple band structure of \documentclass{article}\usepackage{amsmath}\usepackage{amssymb}\usepackage{amsbsy}\pagestyle{empty}\begin{document}$\rm{\Sigma}^{+}_{{{\rm u}}}\leftarrow \rm{\Sigma}_{{{\rm g}}}^{+}$\end{document} electronic transitions of homonuclear diatomic molecules to the highly complex band structure of polyatomic molecules subject to strong vibronic interactions are used to illustrate the richness of electronic spectra.

Global Analytical Potential Energy Surfaces for High‐resolution Molecular Spectroscopy and Reaction Dynamics

“…In principle, wavefunctions and eigenvalues carry a second index, which also numerates the potential hypersurface V , but this index may be omitted, for simplicity, whenever restriction to a single electronic state is a sufficiently good approximation (see : Fundamentals of Rotation-Vibration Spectra, this handbook). For other cases, we refer to the review by Wörner and Merkt (2011): Analytic Derivative Methods in Molecular Electronic Structure Theory: A New Dimension to Quantum Chemistry and its Applications to Spectroscopy, this handbook. General, exact solutions of this problem are difficult to obtain and intense research is being carried out currently in this field (see also Domcke et al 2004).…”

Molecular Quantum Mechanics and Molecular Spectra, Molecular Symmetry, and Interaction of Matter with Radiation

“…Further examples of electronically allowed and electronically forbidden transitions are presented in Wörner and Merkt (2010).…”

“…( (Wörner and Merkt 2010)) provide a more rigorous introduction and more detailed information on group theory and its applications to molecular physics and spectroscopy. They also contain many references to further articles and textbooks on group theory.…”

“…While many groups used to describe the symmetry properties of molecules have a finite number of elements, infinite groups, i.e., groups with an infinite number of elements, also exist, examples being the C ∞v and D ∞h point groups of linear molecules and the K h group used for atoms. The use of infinite groups is illustrated by several examples in Wörner and Merkt (2010). In this introductory article, only finite groups are used as illustrations.…”

A Spreadsheet To Facilitate Group Theory Calculations and Display of Character Tables

“…I have produced a spreadsheet containing character tables for all 50 of the chemically significant point groups as listed by Cotton 6 and by Worner and Merkt. 7 The spreadsheet will decompose arbitrary representations to irreducible representations and calculate direct products of representations. Therefore, it takes care of the tedious calculations, but leaves all chemical interpretation to the user.…”