Optimal coding of vector-functions

Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 40, No. 6, pp. 737–743, November–December, 1988.     

Photoelectric characteristics of photodetectors based on a GaAs/CuPc heterojunction

A study is made of the volt-ampere, volt-farad, and spectral characteristics of photodetectors based on an n-GaAs/p-CuPc heterojunction. When exposed to white light (E=600 W/m²) through Ag, the elements Cu/GaAs/CuPc/Ag have the following characteristics: U_xx=0.6 V; I_sc=30.2 A/m², FF=0.49. Based on this data and with allowance for the transmission factor (τ=7%), η=18%. Quantum efficiency is 0.5 el./phot. in the UV-region at λ₁ = 300 nm, while α₂ = 0.85 el./phot. in the visible region at λ₂ = 800 nm. The limiting sensitivity of the photodetector is 10⁻¹¹ W. The following was determined from the volt-farad and spectral characteristics: C_b=8.6·10⁻⁴ F/m²; barrier width w₁=16nm in CuPc and w₂=34 nm in CaAs; exciton diffusion length L₁=2.5 nm and L₂=7.5 nm, respectively. The photodetectors undergo almost no degradation. The values of U_xx and I_sc remain constant with multiple exposures to UV-light of 140 W/m² intensity over 6 h at constant temperature. The sensitivity region of the photodetectors is from 200 to 1000 nm. It is found that an anisotropic heterojunction in the form of two series-connected Schottky barriers is created at the boundary between n-GaAs and oxygen-doped p-CuPc in the presence of charged surface states at the interface. Vologda Polytechnic Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 41–45, July, 1996.     

On linear widths of classesH ω

We obtain new results related to the estimation of the linear widths λ _N and λ ^N in the spacesC andL _p for the classesH ^ω (in particular, forH ^α, 0<α<1). Institute of Mathematics, Ukrainian Academy of Sciences, Kiev. Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 48, No. 9, pp. 1255–1264, September, 1996.     

On the best approximation of periodic functions of two variables by polynomial splines

We consider the problem of the best approximation of periodic functions of two variables by a subspace of splines of minimal defect with respect to a uniform partition.     

TPD studies of benzene adsorption over vanadium-molybdenum oxide catalysts

Benzene is shown to be adsorbed on the surface of a V₂O₅-MoO₃ catalyst in two forms. The activation energies of benzene desorption for its first and second forms are 50 and 134 kJ/mol, respectively, in the latter case the adsorption proceeding with dissociation.

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, - . 50 / –134 /, .