Visible Optical Absorption Spectra Research Articles

Fluorescence Properties of the Ru(bpy)32+ Complex Incorporated in Sol−Gel-Derived Silica Coating Films

Silica gel coating films doped with Ru(bpy)32+ complexes were prepared by the sol−gel method from a hydrolyzed tetraethoxysilane solution containing [Ru(bpy)32+]Cl2·6H2O. UV−visible optical absorption spectra, fluorescence emission spectra, fluorescence efficiency and lifetime, and infrared absorption spectra were measured for the films dried at various temperatures. The fluorescence band attributed to the transition from the metal-to-ligand charge transfer excited state to the ground state of Ru(bpy)32+ was found to show blue shift on sol-to-gel film conversion, red shift with increasing drying temperature up to 200 °C, and then blue shift again over 200 °C. The fluorescence lifetime increased and the fluorescence efficiency decreased with increasing drying temperature. In the as-deposited film, the complexes are thought to be surrounded by the solvent molecules which interact with the silanol groups of the gel network so strongly that the Franck−Condon excited state of the complex may be relaxed to a le...

Optical absorption of poly(3-alkylthiophenes) at low temperatures

We present ultra-violet visible optical absorption spectra of thin solid films of four poly(3-alkylthiophenes) between 10 K and room temperature. The thermochromic shift in the optical absorption turns out to be detectable down to about 200 K. An interpretation of the fine structure in the optical spectra is also made in terms of vibronic structure caused by the CC stretching vibration of the thiophene ring close to 1460 cm −1.

Electrolytic coloration of cuprous chloride crystals

Electrolytic coloration of cuprous chloride crystals is observed. Visible optical absorption spectra, coloration kinetics so as electric current kinetics are recorded at high temperature. EPR experiments are performed both at high temperature and with quenched samples. Two types of defects are found, one being metastable, the other stable, remaining after quenching. All experimental results do not agree with the classical theory of absorption of light by metal colloids. A model is proposed which qualitatively explains all experimental features of these phenomena.

Abstract of the in vivo synthesis of labile methyl groups : S. Jonsson and W.A. Mosher ( J. Am. Chem. Soc., 72, 3316 (1950))

A series of CdS and CdS/CNTs photocatalysts were successfully prepared by hydrothermal method and they were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV–visible optical absorption spectra (UV–Vis), etc. By studying their photocatalytic properties, it is found that, for CdS, photocatalysts prepared in appropriate alkaline environment presented higher hydrogen production activity, reaching 794.6 μmol h−1 g−1; the photocatalytic activity of CdS was obviously enhanced by combining it with CNTs via a special two-step hydrothermal method, and the corresponding hydrogen production rate reached 1.771 mmol h−1 g−1; the photocatalytic activity was further improved by loading co-catalyst NiS, achieving 12.13 mmol h−1 g−1.