Ursula Dettlaff-Weglikowska

Polarized Raman spectroscopy study of SWCNT orientational order in an aligning liquid crystalline matrix

Liquid crystals are self‐organizing anisotropic fluids. In this work the transfer of order from liquid crystals to single‐wall carbon nanotubes embedded in them is exploited within the geometry of standard cells used for large‐scale alignment of liquid crystals. Using Polarized Raman Spectroscopy the alignment of the SWCNTs along the common liquid crystal direction is unambiguously demonstrated through the analysis of the variation of the peak intensity of the nanotube Raman modes with respect to the polarization direction of the light.

Local and electronic structure of siloxene

Silicon L 2,3 x-ray emission spectra (XES) of siloxene powder samples prepared according to Woohler and Kautsky (Wohler and Kautsky siloxene) are presented. The results are compared with the Si L 2,3 spectra of the reference compounds a -Si, c -Si, SiO 2 , and SiO x . A close similarity of the electronic structure of Wohler siloxene to that of a -SiO 0.43 : H and of Kautsky siloxene to that of a -SiO 0.87 : H is found. We determine the number of oxygen atoms per Si atom at ~0.5 in Wohler siloxene and ~0.8 in Kautsky siloxene. The relative concentrations are in good agreement with the results of infrared absorption measurements on the same samples.

Raman Spectroscopy of Carbon Nanotube‐Polyaniline and Functionalized CNT/SOCl2 Films

Different transparent conducting heterostructures as thin films on transparent plates have been obtained: a thin network of Carbon Nanotubes (CNT), 80% to 93% transparent and enough conducting to be used as anode, on which Polyaniline is deposited electrochemically. In order to obtain information about the possible interaction between CNT and the polymer, we analysed the Raman spectra, on these hetero‐thin films obtained at different chemical and electrochemical conditions. To compare, we analysed by Raman spectroscopy self‐standing CNT‐Polyaniline films where polyaniline was electrochemically deposited on a thick network of CNT (bucky‐paper). Electrical conductivity and optical transparency are measured: Polyaniline improves the conductivity by a factor from 2 to 3 for films where the transparency is 67%. The best transparency, 93% to 97%, is obtained with SOCl2 functionalized CNT thin networks.