E. G. Guk

Electrical properties of the conducting polydiacetylene poly-1,1,6,6-tetraphenylhexadiinediamine

The electrical properties of the conducting polydiacetylene poly-1,1,6,6-tetraphenylhexadiinediamine (poly-THD) are investigated for the first time. The stability of the conductivity with time, the current-voltage characteristics over a broad range of applied voltages, the pressure dependence of the conductivity, and the low-frequency conductivity fluctuations in the range of analysis frequencies 20 Hz–10 kHz are studied. Appreciable anisotropy of the conductivity is discovered under strong uniaxial compression. Hooge’s parameter α is evaluated (α∼20 at 300 K).

New approach to achieving the potentially high conductivity of polydiacetylene

It is postulated that only the surface layers of the structural formations are doped in single crystals of various polydiacetylenes because of the high packing density of their macromolecules and that this is the reason for the low level of conductivity attained in these conjugated polymers. For the purpose of raising the efficacy of the doping process by increasing the surface-to-volume ratio of the polymer, single crystals of the polydiacetylene poly-1,1,6,6-tetraphenylhexadiinediamine (poly-THD) are ground by various methods. A correlation between the particle size of the ground single crystals and their dc conductivity in the doped state is discovered. A record value of the conductivity (3×10−2 S/cm) for polydiacetylenes, which is more than two orders of magnitude higher than published values (10−3–10−5 S/cm), is achieved.

Spatial localization of temporal noise in digital channels

The feasibility of temporal noise spatial localization in a communication channel intended for digital signal transmission is studied. As in the case of temporal noise localization for analog signals, we use the Hadamard integral transformation with specially ordered basis functions. When the noise intensity is estimated through the probability of error in determining the output signal with different lengths of digital words, the localization of noise for digital signals is shown to be identical to that of analog signals.

Theory of Hadamard two-dimensional transformation extended for space-localized additive noise

The results of analysis and simulation of the space-localized noise spectrum with a known correlation characteristic are presented. The case under consideration is use of spatially sequential combinatorics when the Walsh-Hadamard transformation matrix elements transmitted through a communication channel are ordered in rows and columns.

Changes in the optical properties of conducting polydiacetylene THD brought on by doping

Changes in the optical properties of conducting polydiacetylene THD (poly-1,1,6,6-tetraphenylhexadiindiamine) brought on by doping are investigated for the first time. Spectral dependences of the extinction coefficients were studied in the range 400–25 000 cm−1 both for the undoped polymer (σ<10−9 S/cm) and at various doping levels (up to σ∼5×10−3 S/cm). The results obtained attest to the appearance of high carrier concentrations in polydiacetylene THD with conductivities σ⩾10−4 S/cm. The relatively low observed macroscopic conductivity is explained by the complex hierarchy of structural formations that are intrinsic to polymers. The results obtained are compared with the corresponding data for conducting polyacetylene.

Determination of the dimensions of the conjugation region in copolymers of ethylene and acetylene by resonance Raman scattering

Resonance Raman scattering is used to determine the sizes and size dispersion of defect-free conjugation regions in copolymers of ethylene and acetylene containing 2–24 mol % of a rigid polyacetylene fragment. In addition to extended sequences containing up to 70–100 double C=C bonds, there is a substantial fraction of short (15–25 C=C) conjugated fragments. The size distribution of the conjugation regions in the ethylene-acetylene copolymer is close to that observed in pure polyacetylene synthesized in the conventional way. A model is proposed for the distribution of these sequences in hypermolecular ethylene-acetylene copolymer formations.

Simulation and study of material with diffuse scattering in the near- and mid-IR spectral ranges

Fabrication of efficient scattering materials based on uniform layer of metallized fine powder on the surface of thermoplastic polymer is analyzed. Spectra of diffuse reflection and scattering indicatrix of the materials in the near- and mid-IR spectral ranges are studied.

Suppression of the effect of high-power background illumination on the precision of determination of the optical signal coordinates

The effect of the intensity of background illumination on the steepness of the current—voltage characteristic and the precision of determining the position of a modulated optical signal is investigated experimentally for the Multiscan position-sensitive detector. The suppression of the effect of a nonuniform background illumination on the precision of determining the coordinates of the signal is estimated using the two-aperture synthesis.

Features of temporal noise spatial localization while indexing in accordance with the 2D hadamard transform

It is shown that the 2D indexation of a communication channel 1D noise with the help of the 2D Hadamard transform makes it possible to represent the distribution of this noise in the restored image space in the form of a 2D distribution of its variance. The width of noise variance distribution depends on the extent of preservation of correlation between elements of communication channel 1D noise. It is shown that the degree of 2D spatial localization of noise in this case exceeds the degree of noise localization in the case when 1D Hadamard transform is used.

Novel principle of optical signal sensing based on the creation of signal statistical estimates

A new approach to the optical signal sensing as the creation of its statistical estimations allows not only improving the procedure accuracy, but expanding its functional capabilities. The use of the moving adaptive ampere-voltage characteristic with a controlled shape and sensor topology optimization which provides maximum continuous response field leads to the increase of the sensor resolution up to 0.03 µm (10−6 of the total device length). This approach made it possible to create a set of quantile readings characterizing a signal shape, to determine the direction to the optical signal source under signal shape distortions, and to locate a faint optical boundary.