Recent Advances in Gas Electron Diffraction and Structural Studies by Join Quantum Mechanical and Experimental Procedures

Abstract

Gas electron diffraction (GED) is a powerful tool of structural chemistry. This field is currently undergoing important change because of the recent development of multichannel real-time data acquisition procedures which are more versatile than the conventional photographic detection methods. Direct detection enables studies of transient species and time-resolved investigations using pulsed electron beams. It is a characteristic of GED that closely spaced bond distances and angles are not resolved by the data due to molecular disorder in gases. Therefore, ab initio geometries are useful in GED studies, because calculated differences between bond distances and angles can be used to constrain least squares GED data analyses. This area of structural chemistry, involving interactive quantum mechanical and experimental studies, is currently also undergoing an important development, because the accuracy of the calculated constraints can be tested in a novel way by MP2- gradient optimizations.