Iodine resonance Raman

It turns out that the CSP approximation dominates the full wavefunction, and is therefore almost exact till t 80 fs. This timescale is already very useful The first Rs 20 fs are sufficient to determine the photoadsorption lineshape and, as turns out, the first 80 fs are sufficient to determine the Resonance Raman spectrum of the system. Simple CSP is almost exact for these properties. As Fig. 3 shows, for later times the accuracy of the CSP decays quickly for t 500 fs in this system, the contribution of the CSP approximation to the full Cl wavefunction is almost negligible. In addition, this wavefunction is dominated not by a few specific terms of the Cl expansion, but by a whole host of configurations. The decay of the CSP approximation was found to be due to hard collisions between the iodine atoms and the surrounding wall of argons. Already the first hard collision brings a major deterioration of the CSP approximation, but also the role of the second collision can be clearly identified. As was mentioned, for t < 80 fs, the CSP... 

The functionalization of zinc porphyrin complexes has been studied with respect to the variation in properties. The structure and photophysics of octafluorotetraphenylporphyrin zinc complexes were studied.762 Octabromoporphyrin zinc complexes have been synthesized and the effects on the 11 NMR and redox potential of 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraarylporphyrin were observed.763 The chiral nonplanar porphyrin zinc 3,7,8,12,13,17,18-heptabromo-2-(2-methoxyphenyl)-5,10,15,20-tetraphenylporphyrin was synthesized and characterized.764 X-ray structures for cation radical zinc 5,10,15,20-tetra(2,6-dichlorophenyl)porphyrin and the iodinated product that results from reaction with iodine and silver(I) have been reported.765 Molecular mechanics calculations, X-ray structures, and resonance Raman spectroscopy compared the distortion due to zinc and other metal incorporation into meso dialkyl-substituted porphyrins. Zinc disfavors ruffling over doming with the total amount of nonplanar distortion reduced relative to smaller metals.766 Resonance Raman spectroscopy has also been used to study the lowest-energy triplet state of zinc tetraphenylporphyrin.767... 

The macrocyclic phthalocyanine ligand will form a complex Pt(phthalocyanine).1106 The crystal structure shows two polymorphs present because of molecular packing.1107 The platinum is in a square planar coordination geometry with a mean Pt—N distance of 1.98 A. The complex can be partially oxidized with iodine to give conducting mixed valence solids.1108 Eighteen fundamental and overtone combination bands are observed in the resonance Raman spectrum of platinum phthalocyanine, and from this data the symmetry of the excited singlets are found to be Dy.. Qlv or D2.1109... 

Structure of Poly iodine from the Resonance Raman Spectrum.Ill... 

Resonance Raman Spectra of Specimens Soaked at High Iodine... 

Our resonance Raman spectrum study on iodinated blue films showed that both I5 and I3 mode polyiodines form in the films, and the former prevails over the latter in the amorphous phase of PVA. On the other hand, the spectra of the specimens soaked at high iodine concentrations show that the I3- mode complex forms in the crystalline phase. Then the color of the films is not blue but purple or almost red. 

Figures 28 and 29 show resonance Raman spectra of two specimens soaked at low and high iodine concentrations. In the previous section, both the 109 cm-1 and the 161 cm-1 peak are assigned to I3- and I5- mode polyiodines, respectively. According to Fig. 28 the intensity ratios are different between the two specimens the 109cm-1 peak is stronger than the 161 cm-1 peak in the heavily iodinated specimen. This corresponds to the fact observed at high iodine concentrations that the I3- mode polyiodines is formed within crystals and that the visible light absorption peak due to I3- mode complex remarkably increases its intensity as shown by Fig. 29. According to Fig. 29, the 109cm-1 peak intensity is enhanced much more by 488 nm excitation than by S14.Snm excitation.

Fig. 28. Resonance Raman spectra (v0 514.5 nm) of iodinated PVA films soaked in iodine solutions of different iodine concentrations, (a) 5 x 10 3 mol/l, (b) 1 x 10 1 mol/1...

In Sect. 6, the complex formation in the crystalline phase of PVA which is caused at very high iodine concentrations in the soaking solution was studied In this case, the X-ray diffraction completely changes from that observed at low iodine concentrations, and both resonance Raman and visible light absorption spectra demonstrate that the I3- mode complex is formed in the crystalline phase. The iodine absorbed in the crystalline phase forms a co-crystal with PVA whose model is proposed on the basis of the equatorial X-ray diffraction. However, it should be noted that the adsorption does not occur uniformly throughout a crystal, as suggested by the extraordinary broadening of the X-ray diffraction. The structure of the complex formed in the crystalline phase is... 

Iodine oxidation of Ni(PC), Ni(TBP) and Ni(TATBP) in each case yields crystals of composition Ni(L)I. Full X-ray diffraction, resonance Raman and 129I Mossbauer studies show that the first... 

Iodine oxidation of Ni(OEP) and Cu(OEP) yields polycrystalline materials with a range of stoichiometries.108 Resonance Raman studies indicate the presence of I5- in contrast to the I3 observed for larger ring macrocycles. Single crystal studies of Ni(TMP)I indicate a metal-over-metal stack arrangement but with the Ni(TMP) unit puckered. The iodine superlattice is incommensurate with the Bragg lattice.107 The room temperature conductivity is 10 Q-1 cm-1 and increases on lowering the temperature to reach a rounded maximum at 115 K. The spin susceptibility is temperature independent down to a transition temperature of 28 K, well below the conductivity maximum. Below 28 K the susceptibility decreases in an activated fashion with Ajk 60 K.108... 

Iodine oxidation of M(TAAB), where M = Pd or Pt, yields compounds of the type [M(TAAB)]Ig j. Resonance Raman studies indicate the presence of I3- and, therefore, the compound should be formulated as (MTAAB)2 7+(I3-)2.7. Room temperature conductivities of single crystals are relatively low (Pd, 10-7 Pt, 10 4 Q-1 cm-1) but increase by 103 (Pd) or 10 (Pt) at 10 kbar pressure.109... 

The first report of high conductivity with small-ring metallomacrocycle is found in the study of the iodine oxidation products of metallooctaethylporphyrins, M(oep)134. Iodine oxidation of Ni(oep), Cu(oep), and H2(oep) yields polycrystalline materials with a range of stoichiometries. Resonance Raman spectroscopy indicates that the iodine occurs as the polyiodide IJ species, and thus the materials present an interesting contrast with the large-ring M(L)IX compounds, where, to date, iodine occurs only as the I3 anion. 

Fig. 19.—Resonance Raman spectrum of the amylose (DP 25)-iodine complex. (Reprinted with permission from B. Pfannemueller and G. Ziegast, Staerke, 35 (1983) 7-11.)...

Iodine forms a well-known blue complex with the amylose form of starch. From resonance Raman and I Mossbauer spectroscopy it has been shown that the color is caused by a linear array of I5 (I2I I2) repeating units held inside the amylose helix. 

Raman spectra of chlorine, bromine, and iodine gas were first recorded by Flolzer et al. (1970) with argon laser excitation, the latter two halogens showed a strong resonance Raman effect. The numerous results of later investigations are presented in Sec. 6.1. on the resonance Raman effect. 

In 100%, H2SO4 the disproportionation of to and an iodine(III) species, probably I(S04H)3, is essentially complete, and only traces of la can be detected by means of its resonance Raman spectrum. 

Resonance Raman spectra (a) and M6l5bauer spectra (b) of the starch-iodine complex (A) and the model substance (trimesic acid H20)re Hl (B)... 

These lowest-order contributions were used by Nafie etal. (16) to calculate the relative intensities of the series of overtones observed in the resonance Raman spectrum of iodine vapour (see Section 4.1). The calculated intensities were found to fall... 

Diatomic cations, neutral molecules, and anions represent the type of inorganic species which has been most extensively studied by resonance Raman spectroscopy. Iodine in the gaseous, dissolved, and matrix-isolated states has been the subject of particularly detailed studies, and it is this molecule for which the greatest number of members (25) of a resonance Raman progression has so far been observed (66). The relation between resonance Raman and resonance fluorescence spectra has been discussed in Section 2, but it is worth illustrating the general principles involved by reference to the work on iodine. 

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