Electronic Raman

In addition to experiments which were possible with conventional lamps but can be much more easily performed with lasers, there are some investigations which have to be done within certain exposure times or signal-to-noise ratios and these have only been possible since lasers have been developed. This group includes the electronic Raman effect 195-197) observation of Raman scattering in metals where the scattering quasi particles are phonons, Raman studies of vibrational spectra in semiconductor crystals or the resonance Raman effect 200-202)... 

A complete study of the electronic states of the / configuration of CeClj using the electronic Raman effect has been performed by Kiel eta/, Two pure antisymmetric transitions were observed which are forbidden by normal symmetric tensor selection rules. In this paper the general features of the electronic Raman effect are... 

Association between lanthanide ions and azide or thiocyanate ions has been studied in solution by electronic, Raman and NMR spectroscopy.186,187 The complexation constant in water between Nd3+ and N3 is approximately 2.5. Longitudinal relaxation time studies for Gd-Dy indicate that the M—N—NN angle is bent (135° approximately). 

We used short broadband pump pulses (spectral width 200 cm 1, pulse duration 130 fs FWHM) to excite impulsively the section of the NH absorption spectrum which includes the ffec-exciton peak and the first three satellite peaks [4], The transient absorbance change signal shows pronounced oscillations that persist up to about 15ps and contain two distinct frequency components whose temperature dependence and frequencies match perfectly with two phonon bands in the non-resonant electronic Raman spectrum of ACN [3] (Fig. 2a, b). Therefore the oscillations are assigned to the excitation of phonon wavepackets in the ground state. The corresponding excitation process is only possible if the phonon modes are coupled to the NH mode. Self trapping theory says that these are the phonon modes, which induce the self localization. 

Mechanisms. Studies of model reactions473-476 and of electronic, Raman,456 477 478 ESR,479/480 and NMR spectra and kinetics481 have contributed to an understanding of these enzymes.459 461 464 482 483 For these copper amine oxidases the experimental evidence suggests an aminotransferase mechanism.450 453 474 4743 d Tire structure of the E.coli oxidase shows that a single copper ion is bound by three histidine imidazoles and is located adjacent to the TPQ (Eq. 15-53). Asp 383 is a conserved residue that may be the catalytic base in Eq. 15-53.474b A similar mechanism can be invoked for LTQ and TTQ. 

The rotational structure of the electronic Raman band of nitric oxide could also be resolved 7 >. 

As part of a search for other ligands capable of adopting a square-planar configuration about a metal atom and thus potentially able to form stacked units our attention was drawn to the ligand H2P2052- (diphosphonate), usually abbreviated pop. Platinum complexes of this ligand - in particular [Pt2 (pop) i,] l - have already been subject to interesting studies of their luminescence, electronic, Raman and infrared spectra (12-161. Our initial objectives were to try to incorporate [Pt v(en)2X2]2+ (en =... 

The zeroth-order electronic Raman cross-section, /, for a transition from state i to state f, was calculated according to,... 

Fig. 1. Experimental and theoretical electronic Raman Spectra of CaO Cu2+. The experimental spectrum (a), is reproduced from the work by Guha and Chase [1] and was collected at 4.2 K in a polarization geometry which facilitates the observation of transitions of Eg symmetry only. The theoretical spectrum was calculated using equation (9) employing the following parameters hco = 330 cm-1, Af = —1900 cm-1, Af = —0.65 cm-1, Sd 3 cm-1, Se = 3 cm-1, nv = 40, T = 7 K.

As already mentioned in Sec. 4.3.1.2, the unpaired electron in the molecule NO gives rise to two states 17 2 and n a- A Raman transition between these states is allowed and was detected by Rasetti (1930b) at about 120 cm . This electronic Raman effect was rotationally resolved by Fast et al. (1969) and Rich and Welsh (1971). The rotational... 

Electronic Raman scattering originates not only from free electron excitations, but also from collective electron excitations in the form of plasmons. So far, these two types of excitation have been observed only in conventional semiconductors and to some extent in high temperature superconductors, as discussed in subsections 4.8.4 and 4.8.5. However, doped polymers with not too high carrier concentrations or charge transfer systems are possible candidates, and the search for electronic Raman scattering in such systems is one of the challenges in this held. 

Figure 4.8-23 Raman lines for the ai-0(2,3) mode of ErBa2Cut07 as measured above and below Tc, according to FriedI et al., 1990 (a) and electronic Raman scattering of single crystal YBa2Cu307 at various temperatures and after subtraction of phonon lines, according to Hackel, 1990, (b).

As mentioned, in UFDMEF conditions, the spectral profile is mostly independent of the molecule, and could therefore account for the lower energy peak of the SERS continuum observed in Ref. [14] (previously attributed to electronic Raman scattering or to LSP luminescence). 

In the Raman spectra of Si, the line shape of the optical phonon peak is quite sensitive to degenerate p-type doping as a result of interference of Raman scattering from a continuum of electronic intravalence band transitions (electronic Raman scattering) with that from discrete phonon excitations (vibrational or phonon... 

Mechanisms. Studies of model reacfions and of electronic, Raman, and NMR... 

Guha and Chase reported that an electronic Raman spectrum could be observed only in experiments that select a component of the polarisability tensor transforming as Eo or Eg. The electronic matrix elements in these polarisation geometries are. 

Fig. 9 Experimental and theoretical electronic Raman spectra of CaO . The experimental...

The calculated electronic Raman transitions were folded with a Lorentzian bandwidth, with constant width across the whole spectrum. 

Electronic Raman Spectrum of Guanidinium Vanadium Sulphate... 

Fig. 23 Experimental (a) and calculated (b) electronic Raman profiles, corresponding to the E(C3) transition depicted in Fig. 22. The theoretical profiles were calculated with AX = 107cm A = 2720 cm hco = 800 cm and T = 14.5 K. The value of used to calculate each profile is given in the figure, along with calculated (b) and experimental (a) values of the zero-field-splitting parameter, D. The electronic Raman transitions were folded with a Lorentzian bandshape, with constant width of 15 cm across the spectrum after [56]...

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