Orientational ordering in 2,6-lutidine near quartz surfaces modified by carbon

In this paper we present experimental results for the optical dichroism of ultra-thin layers of an epitropic liquid crystal, 2,6-lutidine, on a carbon ized quartz substrate. The carbon layer consists of carbon chains with an o rientation perpendicular to the substrate surface. It significantly enhance s the orientational order of the lutidine layers adjacent to the surface. A two-fold increase of the orientational order parameter S for 2,6-lutidine (from 0.22 to 0.45) has been measured due to the influence of the carbon la yer. The inclusion of nitrogen atoms (n(N) = 7%) into the carbon film leads to a further increase of S from 0.45 to 0.65. (C) 2000 Elsevier Science B. V. All rights reserved.