Molecular excited state geometries

It is expected that as the ability of spectrometers to resolve closely spaced rotational and vibrational bands from molecular spectra improves, the number of molecules whose excited state geometries are known will increase. However, it must be realized that the task of determining excited... 

For purposes of discussion, we divide applications of CPL spectroscopy into three categories (1) efforts to develop reliable CPL "sector rules", (2) use of comparative CD and CPL studies to probe excited state geometry changes, and (3) the specific use of the selectivity and sensitivity of CPL to probe details of molecular and electronic structure, and dynamics. Since in this book we are primarily concerned with "analytical" applications of these chiroptical methods, we will emphasize here the last of these categories. 

CPL and CD are based upon similar aspects of molecular structure. It is important to realize, however, that, even if the same states are involved, these measurements do not usually supply redundant information. From the Franck-Condon principle, CPL is a probe of excited state geometry, and CD is a probe of ground state geometry. CPL measurements have some advantages over the measurement of CD, as well as some inherent limitations. The most serious limitation is, quite obviously, that the optically active molecule under study must contain a luminescent chromophore with a reasonable quantum yield. Although this severely limits the range of possible applications of CPL, it does result in a specificity and selectivity that is not present in CD or absorption experiments. 

Section 7), inner-shell ionization spectra (Section 8), geometries of the molecular excited states (Section 9), and ESR hyperfine splitting constants (Section 10). 

Kushwaha P, Mishra P (2000) Electronic spectra, excited-state geometries and molecular electrostatic potentials of aromatic amino acids. J. Photochem. Photobiol., A 137 79-86... 

Energetic Electronic Molecular States and Excited State Geometries by Quantum... 

From a scientific perspective, absorption and fluorescence spectra are a source of fundamental information in many chemical-physical molecular features [1-3]. First, they are two of the most straightforward methods of identifying a compound and thus represent key analytical techniques. Furthermore, advances in pump-probe time-resolved experiments have made absorption and fluorescence spectroscopy ideal tools to monitor the time evolution and outcome of many reactive processes [4]. These techniques can also provide indications of the electronic stmcture of molecules, their ground- and excited-state geometry, and the most relevant vibrational features, just to name a few basic properties. 

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