UV-vis-NIR absorption spectroscopy

E(hv) axis being Eg. Examples of the use of this relation will be provided in the section devoted to semiconductor oxides. 

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Abstract. The synthesis, isolation and multistage chromatographic separation of the Y2 C84, Ce2 C78 n M C82 (M = Y, La, Ce, Gd) was carried out. All these newly synthesized metallofullerenes are characterized by S8-MALDI mass spectrometry and UV-vis-NIR absorption spectroscopy. 

For the first time the possibility of the use of metal (La, Y) hydrides to prepare composite graphite electrodes was studied. The yield of DCB extracts of C2n/M C82 (M = Y, La, Ce, Gd) from soot obtained by evaporation of composite electrodes based on YH3, LaH3, CeH3 or GdH3 is 2-3 % higher (4-5 wt. % of the primary soot) than the yield of the extracts from soot synthesized using the electrodes based on metallic yttrium, lanthanum, cerium or gadolinium. EMF.v Y2 C84 and Ce2 C78 were produced, separated, and isolated for the first time. Their purity was justified by S8-MALDI mass spectrometry and they were characterized by UV-Vis-NIR absorption spectroscopy. 

Fullerenes can be easily chemically reduced by the reaction with electropositive metals [1, 97-99], for example, alkali- and alkaline earth metals. The anions Cjq"" (n = 1-5) can be generated in solution by titrating a suspension of in liquid ammonia with a solution of Rb in liquid ammonia [100], whereupon the resulting anions dissolve. Monitoring of this titration is possible by detecting the characteristic NIR absorption of each anion by UV/Vis/NIR spectroscopy. The solubility of the alkali metal fullerides in the polar solvent NHj demonstrates their salt character. 

Pristine SWCNTs and their fluorinated derivatives, F-SWCNTs, were reacted with organic peroxides to functionalize their sidewalls covalently by attachment of free radicals (Scheme 1.15). The tubes reactivity towards radical addition was compared with that of corresponding polyaromatic and conjugated polyene JT-systems [150, 151]. The characterization of the functionalized SWCNTs and F-SWCNTs was performed by Raman, FT-IR and UV/Vis/NIR spectroscopy and also by TGA/MS, TGA/FT-IR and with TEM measurements. The solution-phase UV/Vis/NIR spectra showed complete loss of the van Hove absorption band structure, typical of functionalized SWCNTs [150]. 

Volumes 50 and 51 of the Advances, published in 2006 and 2007, respectively, were the first of a set of three focused on the physical characterization of solid catalysts in the functioning state. This volume completes the set. The six chapters presented here are largely focused on the determination of structures and electronic properties of components and surfaces of solid catalysts. The first chapter is devoted to photoluminescense spectroscopy it is followed by chapters on Raman spectroscopy ultraviolet-visible-near infrared (UV-vis-NIR) spectroscopy X-ray photoelectron spectroscopy X-ray diffraction and X-ray absorption spectroscopy. 

The absorption spectroscopy in the UV-Vis-NIR is especially rich for the actinides, allowing for fairly simple determinations of the metal oxidation state. The primary absorption bands result from f f transitions, f d and ligand-to-metal charge transfers. The f — f transitions are typically weak since they are forbidden under the LaPorte selection rules. Distortions in symmetry allow for relaxation in these rules and bands in the visible to near-infrared range result. Complexes that contain an inversion syimnetry, for example Pu02CLt, have weaker f- -f transitions (e < 20 cm ). The direct interactions of the 5f orbitals... 

For the first reduction the IR shifts point to a porphyrin-centred electron transfer. This is supported by further spectroscopy on the anion radical complexes [(Por)Ru(CO)(L)]. The observed EPR lines are narrow, unstructured, with g values around 2. The UV-Vis-NIR spectra of the radical anions are characterised by redshifted Soret bands of reduced intensity, a weak structured band system around 600 nm and weak broad absorptions around 800 or 900 nm (see Figure 4.15). Further support comes from resonance Raman investigations on [(OEP)Ru(CO)(THF)] for which the observed Raman bands fit perfectly to those of the [(OEP)VO] radical anion. There is some evidence that if the spectroelectrochemistry is not carried out in very aprotic and unpolar solvents or traces of water are present, the radical anionic complexes are readily transformed. This has been investigated for the [(OEP)Ru(CO)(L)] system, where the use of solvents like MeOH or nitriles for the electrochemical reduction leads to altered species with unreduced porphyrin ligands (see Figure 4.15)." ... 

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