Spectroscopy UV/Vis/NIR

This is usually used to measure the optical absorption spectra of active species (such as rare earth ions, noble metal nanoparticles, and quantum dots) in sol-gel films, between 190 and 2500 nm, with a resolution of 1 nm. From the surface plasmon resonance (SPR) absorption bands of noble metal NPs in sol-gel hosts, the particle sizes can also be evaluated, since the concentration of NPs such as Au and Ag in sol-gel hosts is often too low to be detected by XRD. 

---

Fitch P., Gargus A.G., Remote UV-VIS-NIR spectroscopy using fiber optic chemical sensing, Am. Lab. 1985 17 64. 

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. 

UV/VIS/NIR spectroscopy and ESR spectroscopy. The UV/VIS/NIR spectrum shows a sharp peak at 983 nm and a broad peak at 846 nm. These two absorbances are attributed to allowed NIR-transitions and these values are consistent with spectra of the cation obtained with other methods [2]. EPR spectroscopy of Cgg-cations, produced by different methods, leads to a broad distribution of measured g-values. These differences are caused by the short lifetime of the cation, the usually low signal-noise ratio and the uncertainty of the purity. The most reliable value imtil now is probably the one obtained by Reed and co-workers for the salt Cgg"(CBiiHgClg)-(g= 2.0022) [2,9] (see also Section 8.5). Ex situ ESR spectroscopy of above-mentioned bulk electrolysis solutions led to a g-value of2.0027 [8], which is very close to that of the salt, whereas the ESR spectra of this electro lyticaUy formed cation shows features not observed earlier. The observed splitting of the ESR signal at lower modulation amplitudes was assigned to a rhombic symmetry of the cation radical at lower temperatures (5-200 K). 

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]. 

Ultraviolet-Visible-Near Infrared (UV-vis-NIR) Spectroscopy in Catalysis... 

Experimental Limitations of Applying UV-vis-NIR Spectroscopy under Catalytic... 

UV-vis-NIR spectroscopy is a valuable tool for characterization of solid catalysts on the basis of measurements of electronic and vibrational transitions. The following information may be obtained from the spectra ... 

EXPERIMENTAL OPTICAL ACCESSORIES FOR UV-vis-NIR SPECTROSCOPY IN TRANSMISSION MODE... 

Optical Accessory Design for Diffuse Reflectance UV-vis-NIR Spectroscopy... 

---