Spectral band shape

In a general case parameters re, XdP and y must be determined by self-consistent two-parameter fitting. Owing to the property of orthogonality of Laguerre polynomials, one has for the spectral band shapes... 

The spectra in Figure 12.24 clearly show that the constituent ions in the liquid and in the respective solid salts vibrate rather independent of the surroundings. Therefore the liquid spectrum looks much like the sum of the solid salts. This conclusion is of course not new, but nevertheless it is still quite applicable in the evaluation of many IL Raman (and IR) spectra. However, the presence of conformational equilibria for both of the IL ions makes a closer study worth while. We therefore recommend the interested reader to study the work by Umebayashi et al. [114] in which subtle spectral band shape details, for example, around 930-880 cm are evaluated to show information on the eq-envelope trans-TT and ax-envelope trans-TT interconversion of the [C4QIm]+ ion in the liquid. Also note that the crystal structure of the [CjC4pyr][Tf2N] salt was recently solved it contained the eq-envelope trans-TT conformer of the cation [115]. Also conformers of symmetry Cj and C2 of the [Tf2N] ion show their presence hurried in the band at 400-440 cm-i [109]. 

Figure 5 shows a fluorescence spectrum of perylene (Pe) in a single tri-n-butyl phosphate (TBP) droplet (r = 1.5 fxm) dispersed in water. Although the spectral band shape shorter than 450 nm is somewhat distorted owing to a change in transmittance of the beam splitter of the microscope (Figure 3)... 

Figure 7 shows absorption spectra of a cyan dye (C-Dye) in single DBP droplets in water. The spectral band shape agrees very well with that in a dilute C-Dye/DBP solution (50 /iM). The lowest detection limit of absorbance (A) is 0.05, and the linear response of absorbance is obtained up to A 1.5. This has been confirmed by a droplet radius dependence of A of C-Dye (670 nm). As shown in Figure 8, the absorbance of C-Dye is... 

By dealing with metal ions with different configurations this paper will illustrate the dependence of the spectral band shape on the nature of the metal ion. This, however, is a well-known and reasonably well understood phenomenon. By dealing with a given ion in different host lattices we will illustrate how the spectral band width depends on the nature of the host lattice. This dependence is of a larger complexity. 

The compound K2 [Rh6(CO)15C] is a yellow powder. It is sensitive to air both in the solid state and in solution and is quite soluble in water, methanol, ethanol, acetone, THF, and acetonitrile. The salts of other cations can be obtained by metathesis, in water for the cesium salt and in methanol for the larger tetra-alkylammonium or phosphonium cations. The tetraethylammonium salt is sparingly soluble in THF, whereas the benzyltrimethylammonium and bis-(triphenylphosphine)imminium salts are soluble. All of these salts are soluble in acetone and acetonitrile. The yellow solution of the potassium salt in THF shows characteristic IR bands at 2040 (vw), 1990 (vs), 1885 (vw), 1845 (s), 1830 (sh, m) 1815 (sh, br) and 1775 (vw, br) cm-1. The IR spectral band shapes depend on solvents and cations. The oxidation of K2 [Rh6(CO)i5C] with iron-(III) ammonium sulfate in water under carbon monoxide leads to the octa-nuclear carbido carbonyl cluster Rhg(CO)i9C,6 whereas under nitrogen RhntCO sQ7 or [H30] [Rhls(CO)28C2]8 is obtained. 

The underlying optical phenomena are quite complex and the experimental results cannot be anticipated straightaway. Therefore simulations are generally necessary to discriminate shifts and distortions of spectral band shapes caused by optical effects from those caused by surface-induced changes in structure or chemical bonding (Allara et al., 1978 Porter, 1988). 

The spectroscopic behavior of a JT system is to a large extent governed by the quenching of electronic operators (Ham effect), which causes a shift of the absorption (or emission) bands and a modification of their shapes. Moreover the vibronic mixing of different electronic states can strongly affect relaxation processes, which also modify spectral band shapes. 

The function appearing in eq. (1.28) is of course a time-correlation function. These quantities play a central role in current theories of transport and spectral band shapes. More generally, they are defined as... 

In these measurements, dynamic processes have been analyzed primarily by probing a transient absorption at one wavelength. In general, however, absorption spectra of excited states and chemical intermediates overlap each other. Furthermore, conformational change and orientational relaxation of the surrounding solvent molecules result in a time-dependence of the spectral band shape. For example, intramolecular exciplex systems give an absorption spectrum, the band shape of which is a function of solvent properties and delay times... 

P /P i) mode. This means that the variety of spectroscopic phenomena that can be described if mode mixing is accounted for is considerably richer than in the case of no mode mixing. Some of these effects have been illustrated in Chapters 4 and 7, where the consequences of normal mode rotation on the spectral band shape and radiationless transitions have been investigated. Here, we only note that the displacement parameters (8.14) depend on the matrix W via the dimensioned parameters (Equation 4.69), and therefore some of them can be zero in... 

---