P. Potera

Structural and optical properties of layers of pentacene formed by PLD method

Organic films fabrication offers the possibility of producing electronic devices of low weight, mechanical flexibility and low cost. One suitable material for organic film fabrigation which is the subject of the great interest is pentacene, because it is characterized by the large carrier mobility (∼1 cm2/Vs).In this work, the growth of pentacene layers using pulse laser deposition (PLD) on different substrates (glass/ITO, Si) is described and various processing parameters are investigated. Two pulsed YAG:Nd3+ laser wavelengths were used for the ablation of the PLD target: the first harmonic at 1064 nm aGn:dNdth3+e second at 532 nm. The structure of the layers formed was examined using SEM and RHEED methods. The results were compared with results of optical spectroscopy studies. It will be shown that layers deposed using second harmonics have a higher quality than those for first harmonic. The other PLD parametersalso have a strong influence on the structure quality of layers.

Optical absorption and reflectivity spectra of highly chromium doped CdTe alloy and layer

In the present work, a CdTe alloy doped with a relatively high concentration of chromium (1%), and a CdTe:Cr layer, have been studied. Absorption and reflectivity spectra were measured at room temperature. They indicate the presence of chromium in the divalent state, both in the alloy and in the layer.

Induced absorption in yttrium aluminium perovskite crystals irradiated by 12C and 235U ions

The present work is devoted to investigation of optical absorption in pure and neodymium-doped YAlO3 (YAP) single crystals in the spectral range 0.2–1.1 μm induced by the influence of 12C ions irradiation with energy 4.50 MeV/u (MeV per nucleon) and a fluence 2 × 109 cm−2 or of 235U ion irradiation with energy 9.35 MeV/u and a fluence 5 × 1011 cm−2. The induced absorption in the case of 12C ions irradiation is caused by recharging of point growth defects and impurities under the radiation influence. After irradiation by 235U ions with fluence 5 × 1011 cm−2 the strong absorption rise is probably caused by contribution of the lattice destruction as a result of heavy ion bombardment.

Symmetry of the pentacene molecule and classification of electron states studied in the frame of group action on a set

Pentacene have recently become the subject of intense studies due to their physical properties which follow from the states of their outer-shell electrons that are able to take part in molecule bonding. The symmetry of these molecules provides the classification of quantum states according to the group theory method. In this paper, we apply a molecular state-space factorization scheme for the classification of pentacene molecules based on the structure of their electron states.

Calculation of the atom displacement concentration in YVO4 and PbMoO4 crystals as a function of electrons or neutrons energy

This work is devoted to the calculation of concentration of radiation displacement defects (RDDs, i.e. atoms, cations or anions displaced from positions in lattice and their associated vacancies) in YVO4 and PbMoO4 crystals as a function of particle energy (electrons and neutrons). Energy dependencies of RDD concentrations are discussed in comparison with results of other complex oxide crystals. The obtained results show that the case of electron irradiation the radiation hardness of YVO4 and PbMoO4 is higher than for other oxide crystals.

Influence of impurity ions on the radiation induced optical absorption in YAlO3 and LiNbO3 crystals

Abstract A study of the influence of gamma irradiation (60Co source, 105—106 Gy absorbed doses) on the optical properties of doped YAlO3 and LiNbO3 crystals was performed. The role of Nd, Er, Tm, Ho, Ce, Mn and Ca ions in YAlO3 crystals and Nd, Er, Tm, Yb, Dy, Pr, Fe, Cr and Mg ions in LiNbO3 crystals in the radiation induced optical absorption is discussed.

Concentration of radiation displacement defects in BSO and BGO crystals irradiated by electrons or neutrons

This work is devoted to the calculation of the concentration of radiation displacement defects (RDD) in bismuth germanate and bismuth silicate crystals as a function of particle energy (electrons and neutrons). Energy dependencies of RDD concentrations are discussed in comparison with results for other complex oxide crystals. The obtained results show that for the case of electron irradiation the radiation hardness of BSO and BGO should be similar to other oxide crystals, but for neutrons is drastically smaller. Additionally, for the neutron irradiation, the efficiency of the production of defects in the oxide sublattice is drastically smaller than for other oxide crystals.

Radiation effects in YAlO/sub 3/-Nd and Gd/sub 3/Ga/sub 5/O/sub 12/-Nd laser crystals

The results of influence of ionizing radiation (gamma-quanta with doses 10/sup 2/-10/sup 9/ Gy, high energy electrons and fast neutrons with fluences 10/sup 12/-10/sup 19/ cm/sup -2/) on optical properties and laser performance of YAlO/sub 3/:Nd and Gd/sub 3/Ga/sub 3/O/sub 12/:Nd crystals for solid state lasers of space based LIDAR systems are presented. The mechanisms of radiation defects formation and the origin of color centers are discussed.

Optical and luminescence properties of YAlO/sub 3/:Tm/sup 3+/ crystals

Summary form only given. YAlO/sub 3/:Tm/sup 3+/ (YAP-Tm) crystals are of interest as active media for IR and visible lasers. In the present work results on absorption, photoluminescence and thermoluminescence investigations of YAP-Tm (1 wt%) and YAP-Tm (4 wt%) crystals are presented as well as some laser properties of the crystals on excitation by a laser diode.