Asymmetric electrostatic field

Another parameter that one can extract from a Mossbauer spectrum is the quadrupole splitting. The 3/2 state in either iron or tin is degenerate with respect to an asymmetric electrostatic field, and in such a field these levels will be split into dz 3/2 and 1/2 levels. One can observe transitions either to or from these two levels to the ground state, and this is the quadrupole splitting. It is actually e qQ, where eq is the electrostatic field gradient—i,e., the second derivative of the potential with respect to the coordinate—and eQ is the nuclear quadrupole moment. The typical quadrupole split spectrum for iron is shown in Figure 6, in which the cubic (octahedral) symmetry around the iron atom is de-... 

Neir-Johnson geometry. An arrangement for a double-focusing mass spectrometer in which a deflection of nil radians in a radial electrostatic-field analyzer is followed by a magnetic deflection of 7t/3 radians. The electrostatic analyzer uses a symmetrical object-image arrangement, while the magnetic analyzer is used asymmetrically. 

Figure 6.39 shows the time development of particle concentrations. At long times the kinetics for a symmetric (Da = Db) and asymmetric (Da = 0) cases differ significantly in the latter case reaction proceeds more quickly. Note that the choice of the parameter L — 1 corresponds to the weak electrostatic field the Onsager radius R is small and coincides with the recombination sphere radius r0. The initial dimensionless concentration n(0) = 0.1 is not also too large it is only 10 percent of the maximum concentration which could be achieved under irradiation [12], The magnitudes of these two parameters were chosen to make our computations more time-saving. 

NMR spectra of quadrupolar nuclei are influenced by the interaction of the nuclear electric quadrupole moment with electrostatic field gradients generated at the nuclear sites by asymmetric electron distributions due to chemical bonding. To a first order... 

The group of Lipkowitz et al. also performed computational studies of chiral catalysts using COMFA of an asymmetric Diels-Alder reaction with catalysts containing bisoxazoline or phospinooxazoline ligands that are known to induce asymmetry [20]. Approximately 70% of the variance in the observed enantiomeric excess can be attributed to the sterical field and the remainder of the variance to the electrostatic field. 

The vibrational nodes of the sulfonate group in lightly sulfonated polystyrene ionomers are affected by changes in its local environment. In dry materials, the counterion imposes a strong electrostatic field on the sulfonate anion that polarizes the S-0 dipole and shifts the asymmetric and symmetric vibrations to higher frequencies. The addition of solvent weakens the polarization by the cation and shifts the vibrational frequencies to lower frequencies. These results are explained in terms of a solution shell around the cation. 

In their study of the hydration of Naflon, Lowry and Maurltz(12) concluded that water forms a hydration shell around the cation. This weakens the Interaction between the cation and anion to the point where the electrostatic field of the cation has little Influence on the stretching vibrations of the anion. At this point the three S—0 bonds of the SO anion are Identical and a single asymmetric stretch and a symmetric stretch should occur In the IR spectrum at about 1200 cm and 1034 cm, respectively(19). 

V is the ion volume). A larger contraction in perpendicular direction to the surface of the cation distances than that of the anions creates a highly asymmetric local anion environment, enhancing the local electrostatic field which the anion experiences. This decreases the surface energy because of the term Eq.(4.4). Puckering of the surface gives rise to surface dipole layer. 

The dielectric constant is the electrostatic expression of the interaction of atoms and molecules with macroscopic electric fields rather than with the exceedingly strong fields of individual atoms and molecules. The interaction between the homogeneous outside field and electrically asymmetrical (polar) molecules results in a finite effect, since in these molecules the contributions of positive and negative charges do not cancel. 

Explosive-related chemical Explosive remnants of war Electrostatic discharge Explosives trace detection Explosive vapor detection (U.S.) Federal Aviation Administration Field asymmetric ion mobility spectrometry Fertilizer-Grade AN (ammonium nitrate)... 

---