UV-induced in-plane anisotropy in layers of mixture of the azo-dyes SD-1/SDA-2 characterized by spectroscopic ellipsometry
2008 (English)In: Physica Status Solidi. C, Current topics in solid state physics: Special Issue: 4th International Conference on Spectroscopic Ellipsometry (ICSE4), Weinheim, Germany: Wiley-VCH Verlagsgesellschaft, 2008, Vol. 5, no 5, 1274-1277 p.Conference paper (Refereed)
The optical properties of the azo-dyes SD-1/SDA-2, which are used for photoaligning of liquid crystals (LCs), are investigated with Variable Angle Spectroscopic Ellipsometry (VASE). Films of mixture of SD-1/SDA-2 are deposited by spin coating on silicon wafers. The estimated thickness is approximately 10 nm. To achieve photo-induced anisotropy, one of the samples is illuminated during 15 minutes with linearly polarized UV light followed by thermal stabilization during 1 hour at 150 °C. VASE measurements are performed in the wavelength range 200–1350 nm at several angles of incidence and at different sample orientations. Dielectric functions of azo-dye films without/with polarized UV light illumination were modelled using an ensemble of Lorentz oscillators. The results confirm the diffusion model proposed recently for explanation of the formation of the photo-induced order in azo-dye films under the action of polarized light. Refractive indices, their wavelength dispersion and thicknesses of films of SD-1/SDA-2 are reported here.
Place, publisher, year, edition, pages
Weinheim, Germany: Wiley-VCH Verlagsgesellschaft, 2008. Vol. 5, no 5, 1274-1277 p.
, Physica Status Solidi. C, Current topics in solid state physics, ISSN 1862-6351 ; Vol. 5 Issue 5
Other Materials Engineering
IdentifiersURN: urn:nbn:se:liu:diva-91906DOI: 10.1002/pssc.200777881ISI: 000256862500066OAI: oai:DiVA.org:liu-91906DiVA: diva2:619575
4th International Conference on Spectroscopic Ellipsometry (ICSE4), Stockholm, Sweden, 11–15 June 2007