Encyclopedia of Biophysics

Living Edition
| Editors: Gordon Roberts, Anthony Watts, European Biophysical Societies

Absorption Spectroscopy: Relationship of Transition Type to Molecular Structure

  • Paul Wormell
Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-35943-9_781-1

Synonyms

Definition

A very wide range of organic and inorganic substances can be analyzed using UV and visible absorption spectroscopy. The wavelengths, intensities, and fine structure of the absorption bands are determined by the structures of the neutral or ionic species concerned. For almost all substances, UV and visible absorption spectra are caused by electronic transitions. A spectrum may contain more than one region of absorption, known as a band or band system, as molecules may undergo a range of different electronic transitions.

Basic Characteristics

To a first approximation, electronic transitions may be described as involving different combinations of orbitals: bonding (e.g., σ and π for organic molecules), so-called nonbonding (n), and antibonding (e.g., σ* and π*) orbitals. A simple bonding-to-antibonding promotion model of electronic transitions is an oversimplification that does not adequately explain the spectra of all compounds – for...

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Copyright information

© European Biophysical Societies' Association (EBSA) 2018

Authors and Affiliations

  1. 1.School of Science and HealthWestern Sydney UniversityPenrithAustralia

Section editors and affiliations

  • Alison Rodger
    • 1
  1. 1.Department of ChemistryUniversity of WarwickCoventryUK