Raman studies, resonance

High electron density in the intemuclear region of multiple metal bonds leads to a large polarizability and thus the vibrational features are amenable to Raman studies. Resonance Raman effects are common owing to the presence of... 

The Fe-N mode is at 222 in the R state and 207 cnY in the T state for the a subunits, but only shifted to 218 T state for the (3 subunits. This is consistent with the interpretation that the Fe-imidazole interations are weakened more in the T state of the a subunits than p subunits. Time-resolved resonance Raman studies have shown that the R T switch is complete on a 10 ps tuuescale [38]. Finally, UV excitation of the aromatic protein side chains yields... 

Asher S A and Chi Z H 1998 UV resonance Raman studies of protein folding in myoglobin and other proteins Biophys. 

Zhong Y and McHale J L 1997 Resonance Raman study of solvent dynamics in electron transfer. II. Betaine-30 in... 

The general task is to trace the evolution of the third order polarization of the material created by each of the above 12 Raman field operators. For brevity, we choose to select only the subset of eight that is based on two colours only—a situation that is connnon to almost all of the Raman spectroscopies. Tliree-coloiir Raman studies are rather rare, but are most interesting, as demonstrated at both third and fifth order by the work in Wright s laboratory [21, 22, 23 and 24]- That work anticipates variations that include infrared resonances and the birth of doubly resonant vibrational spectroscopy (DOVE) and its two-dimensional Fourier transfomi representations analogous to 2D NMR [25]. 

Asher S A, Chi Z, Holtz J S W, Lednev I K, Karnoup A S and Sparrow M C 1998 UV resonance Raman studies of protein structure and dynamics XWf/r int. Conf on Raman Spectroscopy ed A M Heyns (New York Wley) pp 11-14... 

Fig. 21. Cluster conversions involving [Fe3S4]+ clusters. The cluster conversion in (c) has been proposed on the basis of EPR, VTMCD, and resonance Raman studies, but has yet to be confirmed by Mossbauer or more direct structural techniques.

Resonance Raman studies on the putative prismane protein would provide other important information. In the frequency region of 200-430 cm the putative prismane protein showed bands that at first sight seemed to be typical for Fe-S clusters, but at a closer look appeared to be broader than those observed in basic Fe-S proteins. Also, the resonance frequencies were slightly different from known Fe-S clusters, and it was contended that A prismane-type [6Fe-6S] core is clearly an excellent candidate in light of the available analytical and biophysical data [28]. 

Resonance Raman studies of the recombinant proteins showed vibrational bands at the 200-430 cm region characteristic of iron-sulfur clusters (124). Most interestingly, on Fe and O isotope sensitive band was detected at 801 cm which could be attributed to either a Fe(IV)=0 species or a monobridged Fe-O-Fe structure. This observation, together with Mossbauer analysis, which indicated a mixed N, 0, and S ligand environment for cluster 2, suggests a Fe-O-Fe or Fe=0 unit as part of the structure for cluster 2. 

Akitt, J. W., Greenwood, N. N. Lester, G. D. (1971). Nuclear magnetic resonance and Raman studies of aluminium complexes formed in aqueous solutions of aluminium salts containing phosphoric acid and fluoride ions. Journal of the Chemical Society, A, 2450-7. 

In most work on electrochemical systems, use is made of two effects that greatly enhance the Raman signals. One is resonance Raman spectroscopy (RRS), wherein the excitation wavelength corresponds to an electronic transition in an adsorbed molecule on an electrode surface. The other effect is surface-enhanced Raman spectroscopy (SERS), which occurs on certain surfaces, such as electrochemically roughened silver and gold. This effect, discovered by Fleischmann et al. (1974), yields enhancements of 10 to 10 . The vast majority of publications on Raman studies of electrochemical systems use SERS. The limitations of SERS are that it occurs on only a few metals and the mechanism of the enhancement is not understood. There is speculation that only a small part of the surface is involved in the effect. There is a very good review of SERS (Pemberton, 1991). 

These results confirm Resonance Raman studies of oxidized rubredoxin from Desulfovibrio gigas, which indicates that there are three bands (43.15, 45.01, and 46.62 meV 348, 363, and 376 cm ) in the region where asymmetric Fe° -S stretch modes are expected [108]. Resonance Raman data of the reduced rubredoxin... 

Heme complexes and heme proteins have also been the subject of NIS studies. Of specific interest have been three features the in-plane vibrations of iron, which have not been reported by Resonance Raman studies [108], the iron-imidazole stretch, which has not been identified in six-coordinated porphyrins before, and the heme-doming mode, which was assumed to be a soft mode. 

Nelson, W. H. Manoharan, R. Sperry, J. F. UV resonance Raman studies of bacteria. Appl. Spectrosc. Revs. 1992, 27, 67-124. 

Okamoto H, Hamaguchi HO, and Tasumi M. 1989. Resonance Raman studies on tetradesmethyl-P-carotene aggregates. Journal of Raman Spectroscopy 20(11) 751-756. 

A. Jorio, A.G.S. Filho, V.W. Brar, A.K. Swan, M.S. Unlu, B.B. Goldberg, A. Righi, J.H. Hafner, C.M. Lieber, R. Saito, G. Dresselhaus, and M.S. Dresselhaus, Polarized resonant Raman study of isolated single-wall carbon nanotubes symmetry selection rules, dipolar and multipolar antenna effects. Phys. Rev. B 65, 121402.1-121402.4 (2002). 

Case Study Time-Resolved Resonance Raman Studies of the Excited States of Tris(Bipyridine)Ruthenium(II) ... 

Chew and Wang(39) have pointed out the possibility of double resonance, that is, that the frequencies of both the excitation and inelastically scattered radiation are resonant. They presented the results of calculations which indicate that double resonance can have a significant effect on the angular intensity distribution of inelastically scattered radiation. This case is of some practical interest, particularly in Raman studies, where coincidence may lead to anomalous Raman band intensities, if both the excitation and the shifted frequency are resonant. 

---