Infrared External Reflection Spectroscopic Study on the Structures of a Conducting Langmuir−Blodgett Film of a Tetrathiafulvalene Derivative

Abstract

Infrared (IR) external reflection absorption spectroscopy was applied to study the structure and its change associated with iodine doping of a Langmuir-Blodgett (LB) film of a tetrathiafulvalene (TTF) derivative, 1,3-dithiole-4-carboxylic acid-2-(1,3-dithiol-2-ylidene)hexadecyl ester (HDTTF, Figure 1), prepared on a silicon wafer. The incidence angle ( ) dependence of the p-and s-polarized IR external reflection spectra were measured and analyzed by a theoretical calculation of reflection absorbance (Ap and As) as a function of the tilt angle of the transition moment of each IR band with an assumed complex refractive index. The results indicated that the LB film before doping consists of cis and trans structures, which have the CdO bonds with cis and trans configurations, respectively, with respect to the neighboring CdC bond of the TTF ring. The TTF ring in both structures are almost perpendicular to the substrate surface with the central CdC bond parallel to the surface. After iodine doping the LB film consists of the cis structure and gives rise to charge-transfer-induced vibronic bands at 1352 and 1252 cm -1 . The analyses of the dependence of Ap of these bands proved that the transition moments of both bands make a tilt angle of about 70°with respect to the surface normal of the substrate, which is consistent with a face-to-face stacking of the TTF rings nearly perpendicular to the surface and the high conduction parallel to the substrate.

Structures of Palmitoyl-l and dl-Lysine Monolayers at the Air−Water Interface − Polarization Modulation Infrared Reflection Absorption Spectroscopic Study

“…1523 cm -1 ) of the amide group of l -PL and dl -PL. R p and R s in eq 3 were calculated by following the procedure based on a three-layered model. ,, In the calculation, the complex refractive indices of water were taken from the literature to be 1.3193 + 0.1366i at 1640 cm -1 and 1.332 + 0.0382i at 1523 cm -1 , and the real part of the anisotropic optical constants of the amide I and II bands was assumed to be 1.5. The imaginary parts of the anisotropic optical constants, which should be expressed in terms of the orientation angles of the amide group, were calculated in the following manner.…”

Introdução às técnicas de reflexão especular e de reflexão-absorção no infravermelho: (2) reflexão-absorção

“…Além de substratos metálicos, a IRRAS também vem se tornando importante na caracterização de filmes finos depositados em semicondutores e isolantes [36][37][38][39][40][41] . A indústria dos semicondutores requer técnicas rápidas e não destrutivas para a análise de filmes finos depositados sobre pastilhas de sílicio durante a manufatura de circuitos integrados em controles rígidos do processo.…”