0-0 Raman mode

The nomesonant background prevalent in CARS experiments (discussed above), although much weaker than the signals due to strong Raman modes, can often obscure weaker modes. Another teclmique which can suppress the nonresonant background signal is Raman induced Kerr-efifect spectroscopy or RIKES [96, 97]. 

The key for optimally extracting infonnation from these higher order Raman experiments is to use two time dimensions. This is completely analogous to standard two-dimensional NMR [136] or two-dimensional 4WM echoes. As in NMR, tire extra dimension gives infonnation on coherence transfer and the coupling between Raman modes (as opposed to spins in NMR). 

When we compare the calculated Raman intensities for armchair, zigzag and chiral CNTs of similar diameters, we do not see large differences in the lower frequency Raman modes. This is because the lower frequency modes have a long... 

Raman modes. Such a symmetry analysis will also be useful for identifying the chirality of CNTs. The spectral features in the intermediate frequency range may come from the finite length of CNTs. The resonant Raman intensity may reflect differences in the DOS between metallic and semiconducting CNTs. 

Selected Resonance Raman Modes of Rieske Proteins and of Proteins Containing a... 

Figure 3 Global Raman imaging Experimental setup and example image of a silicon wafer with letter E printed on it. Image taken at 520 cm 1 (Silicon Raman mode).

Fantini, C., A. Jorio, M. Souza, L.O. Ladeira, M.A. Pimenta, A.G. Souza Filho, R. Saito, Ge.G. Samsonidze, G. Dresselhaus, M.S. Dresselhaus, Step-like dispersive Raman modes in carbon nanotubes. Phys. Rev. Lett. 93,2004, http //link.aps.org/abstract/PRL/V93/el47406. 

If the "localized" formulation of the structure of Ru(bpy)3 as Ru(III)(bpy)2(bpy ) + is realistic, the resonance Raman spectrum of Ru(bpy)3+ can be predicted. A set of seven prominent symmetric modes should be observed at approximately the frequencies seen in Ru(III)(bpy)3, with approximately two thirds of the intensity of the ground state bpy modes. The intensity of the isolated 1609 cm - peak fits this prediction, as do the other "unshifted" peaks. A second set of seven prominent Raman modes at frequencies approximating those of bpy should also be observed. Figure 6 shows that this prediction is correct. The seven Ru(bpy)3+ peaks which show substantial (average 60 cm l) shifts from the ground state frequencies may be correlated one-for-one with peaks of Li+(bpy ) with an average deviation of 10 cm. In addition, the weak 1370 cm l mode in Ru(bpy)3 is correlated with a bpy mode at 1351 cnfl. It is somewhat uncertain whether the 1486 cm l bpy mode should be correlated with the Ru(bpy)3 mode at 1500 cm -1- or 1482 cm 1. It appears clear that the proper formulation of Ru(bpy)3 is Ru(III)(bpy)2(bpy ). This conclusion requires reinterpretation of a large volume of photophysical data (43,45,51 and references therein). 

An example of a RRS spectrum from the yellow solution with Xj=488 nm (u> =20 492 cm-l) is shown in Fig. 4. Also shown are spectra in the v =C regions. The Raman modes of interest are the 667 cra l CHCI3 peak which is used for polymer mode normalization, VC=C at 1520 cm-l and v =C at 2120 cm-l. Analysis of the peaks in the yellow solution is straightforward because the Raman bands do not overlap. 

The Raman modes yC=C and v =C depend on chain length in a manner which parallels the absorption energy dependence on chain length (25). The contribution of each chromophore to the observed Raman peak is determined by the RS intensity for incident light at energy The RS peak position is then a weighted average of all... 

Resonances in x (3) also occur for Raman modes. Enhancement of the 103 output beam occurs when ARaman active molecular vibrations as well as when 2(0j is near an electronic excitation. In this case there is an additional term to be added to X(3), Eq. (1), (23, 37) ... 

One of the most powerful spectroscopic techniques for the detection and characterization of persistent and transient phenoxyls is time-resolved resonance Raman (RR) spectroscopy. Vibrational frequencies and the relative intensities of the resonance-enhanced bands have proven to be sensitive markers for tyrosyl radicals in proteins. For example, Sanders-Loehr and co-workers (31) detected the tyrosyl radical in native ribonucleotide reductase from Escherichia coli by a resonance-enhanced Raman mode at 1498 cm 1 that they assigned to the Ula Wilson mode of the tyrosyl, which is predominantly the u(C=0) stretching mode. 

In contrast to the minimal activity in infrared reflection studies the technique of inelastic electron tunneling spectroscopy (IETS) recently has contributed a large amount of information on monolayer adsorption of organic molecules on smooth metal oxide surfaces,Q),aluminum oxide layers on evaporated aluminum. These results indicate that a variety of organic molecules with acidic hydrogens, such as carboxylic acids and phenols chemisorb on aluminum Oxide overlayers by proton dissociation - 1 — and that monolayer coverage can be attained quite repro-ducibly by solution doping techniques. - The IETS technique is sensitive to both infrared and Raman modes. — However, almost no examples exist in which Raman il and or infrared spectra have been taken for an adsorbate/substrate system for which IETS spectra have been observed. 

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