Nuclear Quadrupole Interaction and Time‐Resolved Perturbed γ‐γ‐Angular Correlation Spectroscopy: Applications in Chemistry, Materials Science, and Biophysical Chemistry. New Analytical Methods (31)

The study of nuclear quadrupole interactions, i.e. of the strength, symmetry, and orientation of the electric field gradient tensor, yields valuable information on charge density distributions on an atomic scale. Apart from the nowadays “conventional” methods of NMR and Mössbauer spectroscopy there is yet another technique: time‐resolved perturbed γ‐γ‐angular correlation spectroscopy. This technique is very well suited for applications in chemistry (e.g. comparative studies of bond conditions of inorganic complexes in the solid and in solution or in the melt), in molecular biology (e.g. intramolecular dynamics in biomolecules), and in materials science (e.g. investigation of catalyst surfaces) because of, inter alia, the extremely small sample requirements and the temperature independence of the sensitivity. The variation of the electric field gradient tensor (strength, symmetry, possibly orientation) is observed as a function of external parameters or, in the case of reactions, as a function of the degree of reaction. The interpretation of results requires the assignment of observed signals to known species or configurations. In this progress report we review modern areas of application of perturbed angular correlation spectroscopy.