Chromophore aggregation and photoinduced dichroism in sol–gel films

Autor:	Danilo Bersani, Iari-Gabriel Marino, Raffaella Raschellà, Pier Paolo Lottici
Rok vydání:	2008
Předmět:	Absorption spectroscopy Carbazole Chromophore Dichroism Condensed Matter Physics Photochemistry Electronic Optical and Magnetic Materials Absorbance chemistry.chemical_compound chemistry Phenomenological model Materials Chemistry Ceramics and Composites Absorption (chemistry) Sol-gel
Zdroj:	Journal of Non-Crystalline Solids. 354:688-692
ISSN:	0022-3093
DOI:	10.1016/j.jnoncrysol.2007.07.072
Popis:	Photoinduced dichroism (PID) and UV–visible spectroscopic studies have been performed in silica-based thin films prepared by the sol–gel technique, containing Disperse Red 1 (DR1) as trans–cis photoisomerizable chromophore and carbazole as a plasticizer. The absorbances parallel and perpendicular to the induced anisotropy axis, A∥ and A⊥, have been monitored during illumination. Some of the samples show an increase of the average absorbance T0 = (A∥ + 2A⊥)/3 over the initial value. This effect can be interpreted by the presence of aggregates of DR1 molecules, breaking down during illumination and increasing the absorption at the probe wavelength. The formation of the aggregates is evidenced by a blue-shift in the absorption spectra. The carbazole apolar group acts as spacers between the DR1 molecules, effectively avoiding the formation of aggregates. Model equations have been proposed to describe the kinetics of the system and the initial PID data have been fitted by using a simple phenomenological model.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::7a2b53f6700289defeeffdeaac8b4ec6 https://doi.org/10.1016/j.jnoncrysol.2007.07.072 Zobrazit plný text záznamu Full Text from ScienceDirect