Resonance Raman spectroscopy electronic band assignments

Resonance Raman Spectroscopy as a Complement to Other Techniques for Making Electronic Band Assignments for (Re2X8)2 Ions... 

The lowest energy dipole-allowed absorption band of [Au2(dcpm)2](C104)2 at 297 nm has been investigated by resonance Raman spectroscopy [61]. The characteristics of the spectrum are fully in accord with the assignment of the absorption band as transition from a filled 5dz2(o ) orbital to an empty 6pz(a) orbital. Analysis of the spectrum in terms of a pure Au Au stretch indicated that the Au - Au distance is shortened by 0.11 A in the excited state, a conclusion which is consistent with a situation in which an electron... 

The first investigation of the phonon modes in binary InN was an extrapolation of the Gai-xInxN (0 < x < 1) alloy modes in reflection towards the binary compound [1], A typically high free carrier concentration in the mid 1020 cm 3 range controls the absorption (Drude absorption) in the infrared and must also account for the broadened Reststrahlen band in pure InN films (e.g. in [1]). In this case infrared active phonons couple to the plasma of the free electrons forming phonon-plasmon coupled modes [10,11], However, layers of low carrier concentration have been achieved and pure LO phonon energies have been derived in Raman spectroscopy. Resonant Raman spectroscopy at 514 nm has been performed, assigning five of the six Raman allowed zone centre phonon modes [8,9] (TABLE 1). 

Biological Aspects.—The lowest excited triplet states of all-rran.s- -carotene produced by pulse radiolysis has been studied by time-resolved resonance Raman spectroscopy.Six transient Raman bands at 965, 1009, 1125, 1188, 1236, and 1496cm were observed and assigned to the triplet state of ) -carotene. The authors conclude that the molecule may be substantially twisted, presumably at the 15,15 band in the triplet state. Further work has also been carried out by the same workers on the triplet state of all-rran -retinal. The results indicate increased 7r-electron delocalization in the triplet state and propose that the relaxed excited triplet-state exists in either sAX-trans or 9-cis conformation. Das and Becker" have also employed pulse radiolysis and laser flash photolysis to study several photophysical properties of the triplet states of the series of polyenals (29)—(33) related to retinal (31) as homologues (Table 35). Results are presented... 

OxyHr is purple in color, associated with a X as near 500 nm, which is polarized perpendicular to the Fe-Fe axis in single-crystal absorbance data (98, 99). Resonance Raman spectroscopy unequivocally assigns this electronic spectral feature to a peroxide-to-Fe(III) charge-transfer band (137-139). Vibrational features at 503 and 884 cm are assigned to v(Fe-02) and v(O-O), based on their sensitivity to substitution. Their enhance-... 

A further aid in assigning a band is its observation in the Resonance Raman (/ / ) spectrum. In RR spectroscopy, the exiting frequency coincides with a symmetry-allowed electronic transition. In general, only the totally symmetric vibrations are therefore enhanced in the RR spectrum (c.f. Sec. 6.1). The entire RR spectrum consists only of a few bands and their overtones. In the following highly symmetric species the totally symmetric breathing modes are easily identified ... 

The electronic absorption spectra of several complexes containing a [Mn (0)2Mn ] core were investigated in detail using MCD spectroscopy in conjuction with resonance Raman and absorption spectroscopies. The MCD spectra of the Mn-oxo complexes were recorded at 300-2,500 nm, deconvoluted, and the component peaks assigned. The majority of peaks corresponded to metal-centered d-d transitions and oxo-to-Mir ligand-to-metal charge transfer (LMCT) bands. Although contributions from the other chromophores in PSII and low protein... 

The resonance Raman spectrum of the class III ascorbate peroxidase isoenzyme II from tea leaves was consistent with an unusual five-coordinate quantum mechanically mixed-spin haem. Porphyrin-ring oxidation state marker bands were assigned for a range of Ru (Por)L2 complexes, where Por = TPP and substituted derivatives, L = PhNO. IR spectroscopy was used to probe the coupling of ground state molecular vibrations with low-energy electronic transitions of Ru(III, II) porphyrin dimer species. ... 

---