Ultraviolet spectroscopy surface acidity

Evidence presented thus far for the putative role played by the photoliberated surfactants has been somewhat circumstantial. Conventional infrared and ultraviolet spectroscopy establish that the photolabile protecting group is photolyzed and the surfactant released under photolysis acid-base indicators, when added to the photosensitive coating, confirm the release of acid for the anionic surfactant derivatives. The surface sensitive spectroscopic techniques of ESCA (Electron Spectroscopy for Chemical Analysis) and RAIR (Reflection-Absorption Infrared) spectroscopy establish the involvement of the surfactant more unequivocally. 

The photochemical and thermal stabilities of Ru complexes have been investigated in detail [8,153-156]. For example, it has been reported that the NCS ligand of the N3 dye, cri-Ru(II)(dcbpy)2(NCS)2 (dcbpy = 2,2 -bipyridyl-4,4 -dicarboxylic acid), is oxidized to produce a cyano group (—CN) under irradiation in methanol solution. It was measured by both ultraviolet-visible (UV-vis) absorption spectroscopy and nuclear magnetic resonance (NMR) [8,153]. In addition, the intensity of the infrared (IR) absorption peak attributed to the NCS ligand starts to decrease at 135°C, and decarboxylation of N3 dyes occurs at temperatures above 180°C [155]. Desorption of the dye from the 2 surface has been observed at temperatures above 200°C. 

Gel-permeation chromatography" is used to compare the pore structure of jute, scoured jute and purified cotton cellulose. Both native and scoured jute have shown greater pore volumes than cotton. The effects of alkali and acid treatment on the mechanical properties of coir fibers are reported." Scanning electron micrographs of the fractured surfaces of the fibers have revealed extensive fibrillation. Tenacity and extension-at-break decrease with chemical treatment and ultraviolet radiation, whereas an increase in initial modulus and crystallinity is observed with alkali treatment. FTIR spectroscopy shows that the major structural changes that occur when coir fibers are heated isothermally in an air oven (at 100, 150 and 200 °C for 1 h) are attributable to oxidation, dehydration and depolymerization of the cellulose component. 

Z. Zhang, N. Yoshida, T. Imae, Q. Xue, M. Bai, J. Jiang, and Z. Lui (2001). A self-assembled monolayer of an alkanoic acid-derivatized porphyrin on gold surface A structural investigation by surface plasmon resonance, ultraviolet-visible, and infrared spectroscopies. J. Colloid Interf. Sci. 243, 382. 

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