Stark effect solvent

Baur, M., Nicol, M. Solvent Stark Effect and Spectral Shifts. J. Chem. Phys. 44, 3337 (1966). 

Three types of electric interactions among a solute and the solvent can be heuristically defined (a) dispersion interactions, (b) interactions due to the transition multipole moments (normally truncated to the transition dipole contribution), and (c) multipolar interactions. Usually, dispersion contributions are simply neglected, whereas the following equations are employed for the evaluation of the shift of absorption energies in terms of polarisability (solute)-dispersion (solvent) (Stark effect), and the polarisability (solute)-polarisability (solvent) interactions, respectively... 

Interactions between a solute and a solvent may be broadly divided into three types specific interactions, reaction field and Stark effects, and London-van-der-Waals or dispersion interactions. Specific interactions involve such phenomena as ion pair formation, hydrogen bonding and ir-complexing. Reaction field effects involve the polarization of the surrounding nonpolar solvent by a polar solute molecule resulting in a solvent electric field at the solute molecule. Stark effects involve the polarization of a non-polar solute by polar solvent molecules Dispersion interactions, generally the weakest of the three types, involves nonpolar solutes and nonpolar solvents via snap-shot dipole interactions, etc. For our purposes it is necessary to develop both the qualitative and semiquantita-tive forms in which these kinds of interactions are encountered in studies of solvent effects on coupling constants. 

The solvent Stark term developed by Baur and Nicols 9) reflects the same qualitative interactions as the reaction field term, however, it concerns the situation when the solute is less polar (in the ideal case non-polar) than the surrounding solvent. Correlations with Stark effects are usually recognized as linear relations to the term... 

All of the interaction mechanisms described above are expected to produce electric fields in the solute cavity. In the case of specific interactions and reaction field effects these electric fields are expected to have some specific orientation with respect to the solute coordinate system. Dispersion forces and Stark effects are not expected to have any specific orientation with respect to the solute. Magnetic field effects seem unlikely to be important in light of the well-known invariance of coupling constants to changes of the external magnetic field. However, it is conceivable that a solvent magnetic reaction field might... 

Electrochemical Stark Effect and the Influence of a Solvent Surface vibrational spectra of adsorbed species on an electrode are often characterized by... 

Applying McRae s equation, and neglecting the Stark-effect (quadratic) term the shift. A /, in the transition energy from the gas phase to that in a given solvent is expressed as ... 

Nonadiabatic electronic transitions are of fundamental importance in chemistry. In particular, because a conical intersection (conical intersection) between two electronic states provides a very fast and efficient pathway for radiationless relaxation [117], there has been much interest in controlling transitions through a conical intersection. Indeed, several methods have already been proposed to control the dynamical processes associated with a conical intersection. One of these concerns the modification of electronic states involved in the conical intersection by environmental effects of polar solvents on the PES (potential energy hypersurface) through orientational fluctuations [6, 67, 68]. Another strategy is to apply a static electric field to shift the energy of a state of ionic character as in the Stark effect ]384, 482] (see Ref. ]403, 404] for the non-resonant dynamical Stark effect). More dynamical methods, which aim to suppress the transition either by preparing... 

Until now we had been talking of gas reactions. Many substances undergo photochemical reactions in liquid state. Again the reaction in initiated by Stark-Einstein law by direct light absorption on the part of reactants. However, it maybe anticipated that quantum efficiency of these reactions will be less than for the same reaction in the gas phase. The reason for this is that in the liquid state an active molecule may readily be deactivated by frequent collisions with other molecules. Furthermore, because of the very short mean free path in the liquid phase free radicals or atoms when formed photochemically will tend to recombine before they have a chance to get very far from each other. The net effect of these processes will be to keep the quantum yield relatively low. In fact, only those reactions may be expected to proceed to any extent for which the primary products of the photochemical act are relatively stable particles. Otherwise the active intermediates will tend to recombine with the solvent and thereby keep the yield low. 

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