Akihito Miyamoto

Structural Analysis of Langmuir-Blodgett Films of Alkylated Tetracyanoquinodimethanes

Structural characterization of alkylated tetracyanoquinodimethane (TCNQ) Langmuir and Langmuir-Blodgett (LB) films has been carried out. Scanning electron microscope (SEM) and atomic force microscope (AFM) observations reveal numerous platelet microcrystal domains in the alkylated TCNQ Langmuir films transferred onto a quartz substrate. The analysis of height distribution in the AFM data proves that these domains have periodic layered structure. The thickness of these layered structures agrees well with the d-values obtained by X-ray diffraction analysis of the alkylated TCNQ LB films. Moreover, the high-resolution AFM image and the d-value of the 2-dodecyl-TCNQ Langmuir film suggest that the structure of the second and the upper layers in the domains is identical to that of the single crystal. SEM and AFM measurements prove that the LB films consist of numerous platelet microcrystal domains which are superposed upon each other, resembling a mosaic structure. Therefore, the periodic structures observed in X-ray diffraction measurements of the alkylated TCNQ LB films are ascribed to the layered structure in these domains, although they are usually explained as well-defined multilayered structure.

Pattern Classification in a Perceptron Circuit Using Lead Phthalocyanine Films

Evaporated films of lead phthalocyanine (PbPc) show a unique conductivity change after a very slight amount of gases are adsorbed. The change in the conductivity of the films depends on the polarity and the strength of input voltages, and therefore is analogous to the change of synaptic connections in nerve systems. Therefore, a perceptron circuit has been fabricated using PbPc films as synaptic connections. After learning via loading of input signals and teacher signals, this circuit can classify random inputs of eight-dimensional voltage patterns into two categories when the input patterns are linearly separable.