Polarizability constants

Further studies of the 2-substituted 5-nitroanilines, conducted by Kier and coworkers, searched for a linear combination of structural variables that describes a line, plane, or surface that separates the molecule classes in the optimum manner. They found that sweetness correlated very well with the substituent polarizability-constants for the 2-substituent, implicating the involvement of the 2-substituents in dispersive-binding interactions at the receptor. This is in agreement with the results of Hansch " and McFarland. The correlation equation was not, however, reported. 

The terms polarizability constant and dielectric constant are often used interchangeably in a qualitative discussion of the magnitude of the dielectric constant. The k values obtained... 

The terms polarizability constant and dielectric constant can be utilized interchangeably in the qualitative discussion of the magnitude of the dielectric constant. The k values obtained utilizing dc and low-frequency measurements are a summation of electronic E, atomic A, dipole P0, and interfacial /, polarizations. Only the contribution by electronic polarizations is evident at high frequencies. The variation of dielectric constant with frequency for a material having interfacial, dipole, atomic, and electronic polarization contributions is shown in Figure 6.1. 

Oq and 02 being the scalar and tensor polarizability constants, respectively, can be determined experimentally and calculated theoretically. For J = 0 or 1/2, for which the formula breaks down, there is only a scalar effect. The Stark effect can be seen as an admixture of other states into the state under study. Perturbing states are those for which there are allowed electric dipole transitions (Sect.4.2) to the state under study. Energetically close-lying states have the greatest influence. A theoretical calculation of the constants Oq and 02 involves an evaluation of the matrix elements of the electric dipole operator (Chap.4). Investigations of the Stark effect are therefore, from a theoretical point of view, closely related to studies of transition probabilities and lifetimes of excited states. (Sects. 4.1 and 9.4.5). In Fig. 2.13 an example of the Stark effect is given different aspects of this phenomenon have been treated in [2.31]. 

We will conclude this section by illustrating how the tensor Stark polarizability constant can be measured using level-crossing spectroscopy. As illustrated in Fig.9,18, for the case of the potassium 5d 03/2 state the unknown Stark effect is measured in terms of the well-known Zeeman effect... 

The Raman spectrum of hydrogen sulfide H2S has been investigated at medium resolution in connection with the measurement of Raman-scattering cross sections [263,264] and polarizability constants [265] and tensors [266], The Q branch of the Vi band was resolved using the CW CARS technique [267] and analyzed by comparison with data from Fourier transform IR spectra [268],... 

V Mazzacurati, MA Ricci, G Ruocco, G Signorelli, M Nardone, A DeSantis, M Sampoli. Rovibrational Raman spectra and polarizability constants of the H2S molecule. Mol Phys 54 1229-... 

The last sequence can be made quantitative by means of the field, resonance and polarizability constants of the ring substituents, crp, and a a [215], respectively ... 

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