Wyniki wyszukiwania - Biblioteka Nauki

1

Optimized structure of SiCxNy–Si(111) interfaces by molecular dynamics simulation

100%

Gruhn W. , Kityk I. V.

Optica Applicata

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2002

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tom Vol. 32, nr 3

347-354

EN

The SiCxNy films were synthesized using a technique of chemical evaporation at low pressures. Films with thickness varying between 8 and 24 nm and with an N/C ratio between 0.1 and 1.5 were obtained. The stoichiometry of these films was measured after their deposition on Si(111) substrates using an extended X-ray absorption fine structure (EXAFS) method. Distances between C–Si and C–N atoms, as well as the molecular dynamics simulations, were done. A comparison of the experimentally obtained and molecular dynamics optimized geometry structure is done. Exchange-correlation potential within a framework of the local density functional approach gives the similar C–Si and C–N bond distances as with inclusions of the non-local many-body screening potential. At the same time pressure derivatives within the local density approach agree better with experimental data.

2

Photoinduced electronic structure and nonlinear susceptibilities in Y-Ba-Cu-O ceramics

100%

Kryza A. , Kityk I. V.

Prace Naukowe. Chemia / Wyższa Szkoła Pedagogiczna w Częstochowie

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2001

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tom Vol. 5

181--188

3

Nonlinear optical investigations of the polymer sufaces modified by the UV-laser illumination.

100%

Kityk I. V. , Makowska-Janusik M.

Electron Technology

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1998

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tom Vol. 31, No. 3/4

447-449

EN

An essential influence of the nitogen laser (λ = 337 nm) photon pluxes, UV-light time exposure and temperature on the behaviour of corresonding nonlinear optical susceptibilities obtained from surfaces for different types of polymers was observed. Temperature dependencies show an existence of at least two components of second harmonic generaton (SHG) intensity. For all the specimens the increase of photoinduced SHG signal with decreasing temperature was revealed, which indicates on the possible low-temperature ordering of the samples under investigations. Correlation between the degree of crystallinity of corresponding surface and the values of SHG signals was revealed. The polyvinyl polymers with different contents of the appropriate organic and inorganic components are selected for investigation, and we report the results of the transient and reflected (SHG) study of the UV-light induced acentrial structural fragments in amorphous polymer surfaces. The data obtained unambiguosuly show that all the nonlinear optical properties are saused mainly by the surface crystallization. The obtained results indicate the possibility of using the obtained results for the investigations of the crystallinity degree of the polymer surfaces. Moreover, it is an effective method of non-contacting control of the structural instability in these materials. Simultaneously we have performed "ab initio" quantum chemical calculations in order to interpret the obtained optical spectra.

4

Metrologia kinetyki fotoindukowanych zmian absorbancji w nanokompozytach krystalicznych

100%

Wojciechowski A. , Kityk I. V.

Elektronika : konstrukcje, technologie, zastosowania

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2011

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tom Vol. 52, nr 12

103-106

PL

Opracowano metodykę pomiarów fotoindukowanych zmian absorbancji w krystalicznych nanokompozytach oraz warstwach stymulowanych laserami o promieniowaniu ciągłym i impulsowym. Pokazano możliwość detekcji zmian absorbancji w czasie rzeczywistym z dokładnością do kilku cm⁻¹ przy ogólnym pochłanianiu rzędu, co najmniej 10⁻³ cm⁻¹, co ma istotny wpływ na parametry nieliniowo optyczne. Przeprowadzono analizę spektralną fotoidukowanej absorbancji w zakresie widma optycznego od 250 nm do 800 nm. Jako źródła promieniowania wykorzystano laser ciągły CW Nd:YAG (532 nm), diody laserowe oraz impulsowy laser, CO₂. Ustalono procesy relaksacji zmian fotoindukowanej transparencji w zależności od przerwy energetycznej, fizykomechanicznych właściwości materiału, ilości nanocząstek, ilości domieszek.

EN

The authors have proposed a method of precise measurements of photoinduced changes in crystalline nanocomposites. It was shown a possibility of detection of photoinduced absorption in the real time of illumination. It was shown a possibility of photoinduced absorpance with precision up to 10⁻³ cm⁻¹ which has an important influence on nonlinear optical parameters. An analysis of photoinduced-absorbed spectrum was carried out within the spectral range 250 nm to 800 nm. As a source of photoinducing beam we have used CW Nd:YAG laser (532 nm), diodes and pulsed CO₂ laser. The processes of relaxation for the photoinduced changes are studied versus the energy gap, physical mechanical properties, number of nanoparticles, number of domains.

5

The IR photoinduced changes in the Y-Ba-Cu-O thin films

80%

Sahraoui B. , Derkowska B. , Kryza A. , Kityk I. V.

Optica Applicata

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2001

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tom Vol. 31, nr 2

445-451

EN

The Y-Ba-Cu-O thin films are promising materials because they have not only superconducting properties but also good optical properties, particularly in the IR spectral range. We investigate the photoinduced optical changes in the IR region for oriented Y-Ba-Cu-O thin films deposited on [left angle bracket]110[right angle bracket] surface of ZnSe single crystals, using differential IR spectroscopy Fourier technique in the spectral region between 100 cm/sup -1/ and 450 cm/sup -1/. We have also found the photoinduced photodarkening effect under the influence of the CO/sub 2/ pulse laser ( lambda =10.6 mu m). The possibility of using the above-mentioned materials as promising materials for IR optoelectronics and nonlinear optics is discussed.

6

Second harmonic generation in Ru-derivative chromophores incorporated within PMMA polymers stimulated by acoustic and optic fields

80%

Migalska-Zalas A. , Kityk I. V. , Sahraoui B.

Opto-Electronics Review

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2005

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tom Vol. 13, No. 2

141-145

EN

We have demonstrated the co-existences of second harmonic generation (SHG) and χ (2) grating using acoustical and optical fields in Ru derivatives incorporated within the PMMA polymer matrices. The investigated compounds possess metastable trapping levels originated both from the d-states of Ru as well as the effective charge transfers due to the presence of p-conjugated states. The investigated compounds possess long-lived χ (2) grating which decreases less than 76% under 600 min of laser treatment. Electrostatic field causes additional reanimation of the SHG. Values of the acoustically induced optical second harmonic generation (AIOSHG) for the best Ru chromophres were substantially higher than for known pure inorganic materials. The effective value of the second-order optical susceptibility for the wavelength 1.89 um is about 1.94 pm/V. With increasing acoustical power, the AIOSHG for fundamental YAB-Gd laser light (λ = 1.76 um) increases and achieves its maximum value at acoustical power density of about 1.45 W/cm2.

7

UV-Induced Anisotropy in CdBr2-CdBr2: Cu Nanostructures

70%

El-Naggar A. M. , Albassam A. A. , Oźga K. , Szota M. , Kityk I. V.

Archives of Metallurgy and Materials

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2015

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tom Vol. 60, iss. 3A

2029--2032

EN

We have found an occurrence of anisotropy in the nanostructure CdBr2-CdBr2: Cu nanocrystalline films. The film thickness was varied from 4 nm up to 80 nm. The films were prepared by successive deposition of the novel layers onto the basic nanocrystals. The detection of anisotropy was performed by occurrence of anisotropy in the polarized light at 633 nm He-Ne laser wavelength. The occurrence of anisotropy was substantially dependent on the film thickness and the photoinduced power density. Possible mechanisms of the observed phenomena are discussed.

PL

Wykryto pojawienie się anizotropii w nanostrukturalnych warstwach nanokrystalicznych CdBr2-CdBr2: Cu. Grubość warstwy zmieniano w zakresie od 4 nm do 80 nm. Nanostrukturalne warstwy otrzymano poprzez kolejne osadzanie na nowych warstwach na podstawie nanokrystalitów. Detekcję anizotropii wykonano w spolaryzowanym świetle lasera gazowego He-Ne o długości fali 633 nm. Anizotropia optyczna występująca w warstwach w znacznym stopniu zależy od grubości warstwy i gęstości mocy indukowanej światłem. Omówiono możliwe mechanizmy obserwowanego zjawiska.

8

Diagnostyka optyczna kompozytów zawierających heterofulereny

61%

Oźga K. , Szota M. , Nabiałek M. , Dośpiał M. , Rakus P. , Kityk I. V.

Przetwórstwo Tworzyw

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2011

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tom [R.] 17, nr 6

488-492

PL

Eksperymentalnie ustalono, że zamieszczenie dwóch atomów germanu w cząsteczce C60 zwiększa podatność optyczną drugiego rzędu kompozytu polimerowego w porównaniu do podstawienia jednym atomem C59Ge. Efektywnymi dla takich kompozytów są metody badawcze oparte na fotoindukowanej drugiej harmonicznej światła SHG i absorpcji dwufotonowej, którą opisuje się tensorami czwartego rzędu i które nie wymagają niecentrosymetryczności badanego materiału. Poszczególne chromofory C59Ge i C58Ge2 (o stężeniu 7 % w j. wag.) wprowadzono do matrycy oligoeterakrylanu (OEA) i fotoutwierdzono światłem nadfioletowym. Jednocześnie dla takich kompozytów przeprowadzono obliczenia odpowiednich hiperpolaryzowalności i ustalano ich związek z podatnościami drugiego rzędu. Obliczenia teoretyczne dla cząsteczek C59Ge i C58Ge2 wprowadzonych do matrycy fotopolimerowej przeprowadzono metodami molekularnej optymalizacji geometrycznej struktury i dynamiki molekularnej. Zoptymalizowana struktura posłużyła do wyznaczenia hiperpolaryzowalności drugiego rzędu metodą chemii kwantowej.

EN

Using experimental methods it was established that replacement by the two germanium atoms in C60 molecule enhances the second order susceptibility of the polymer composites compared with a one-atom substitution C59Ge. More effective for the such composites are the methods based on the photoinduced second harmonic generation (SHG) and two-foton absorption (TPA) which are described by the fourth rank tensors and which do not need non-centrosymmetry. Different chromphores C59Ge and C58Ge2 (with a concentration of 7% in weight un.) were incorporated into the oligoetheracrylate (OEA) polymer matrix and solidification process was performed by using UV light. Simultaneously for such composites were performed the calculations of the corresponding hyperpolarizabilites and was established the relations with the susceptibilities of the second order. Theoretical calculations are performed using the molecular geometry optimization and molecular dynamics for the C59Ge and C58Ge2 molecules incorporated into the photopolymer matrix. This optimized molecular structure was used for the quantum chemical calculation of second-order hyperpolarisabilities.

9

The Relationship between the Monomer Chain Length and the Electro-Optical Properties of Polymer Dispersed Liquid Crystals

61%

Liu J. , Liu X. , Ozga K. , Zhen Z. , Plucinski K. J. , Szota M. , Kityk I. V.

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10

The Relationship between the Monomer Chain Length and the Electro-Optical Properties of Polymer Dispersed Liquid Crystals

61%

Liu J. , Ozga K. , Liu X. , Zhen Z. , Plucinski K. J. , Szota M. , Kityk I. V.

Archives of Metallurgy and Materials

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2016

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tom Vol. 61, iss. 1

457--460

EN

Five polymers dispersed liquid crystalline (LC) films were fabricated using photo-polymerizable monomers with different lengths of carbon chains. These LC films have shown different electro-optical (EO) properties. Through their SEM pictures, the relationship between the linear electro-optical effect and the mesh size of the polymer network was explored. With the increase of number of photo-polymerizable monomers, the mesh size of the polymer network would become larger. So the liquid crystal molecules would be easily oriented in the electric field and therefore, the threshold voltage and saturation voltage would decrease. The open state response times were also reduced and the off state response times would be extended. The DFT simulations have shown principal role of the ground state dipole moments in the observed electro-optical efficiency.

11

Photoinduced Optical Properties Of Tl1−xIn1−xSixSe2 Single Crystals

41%

Myronchuk G. L. , Zamurueva O. V. , Oźga K. , Szota M. , El-Naggar A. M. , Alzayed N. S. , Piskach L. V. , Parasyuk O. V. , Albassam A. A. , Fedorchuk A. O. , Kityk I. V.

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nr 2

12

Photoinduced Optical Properties Of Tl1-xIn1-xSixSe2 Single Crystals

41%

Myronchuk G. L. , Zamurueva O. V. , Oźga K. , Szota M. , El-Naggar N. S. , Alzayed N. S. , Piskach L. V. , Parasyuk O. V. , Albassam A. A. , Fedorchuk A. O. , Kityk I. V.

Archives of Metallurgy and Materials

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2015

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tom Vol. 60, iss. 2A

1051--1055

EN

The influence of temperature on electroconductivity and photoinduced changes of the absorption at 0.15 eV under influence of the second harmonic generation of CO2 laser for the two type of single crystals were investigated. The single crystals Tl1−xIn1−xSixSe2 (x=0.1 and 0.2) have been grown by the two-zone Bridgaman-Stockbarger method. The temperature studies of electroconductivity were done in cryostat with thermoregulation in the temperature 77 - 300 K, with stabilization ±0.1 K. Photoinduced treatment of the investigated single crystals were performed using the 180 ns pulses second harmonic generation of the CO2 laser operating at 5.3 μm. Experimental studies have shown that for the Tl1−xIn1−xSixSe2 single crystals with decreasing temperature from 300 up to 240 K and from 315 up to 270 K the conductivity is realized by thermally excited impurities with activation energies equal to about 0.24 eV and 0.22 eV for x= 0.1 and 0.2, respectively. Photoinduced absorption achieves its maximum at a power density below 100 mJ/cm2. Has been shown that the samples with x=0.2 demonstrated higher changes of the photoinduced absorption with respect to the x=0.1. With further decreasing temperature is observed monotonic decrease in the activation energy of conductivity. The origin of these effects is caused by the excitations of both the electronic as well as phonon subsystem. At some power densities the anharmonic excitations become dominant and as a consequence the photoinduced absorption dependence is saturated what were observed. Additionally, we were evaluated at given temperature the average jump length of R for localized states near Fermi level.

PL

W pracy badano wpływ temperatury na przewodnictwo elektryczne oraz indukowane światłem zmiany absorpcji optycznej przy 0.15 eV, pod działaniem drugiej harmonicznej lasera CO2 dla dwóch typów monokryształów. Monokryształy Tl1−xIn1−xSixSe2 (x=0.1 i 0.2) otrzymano w pionowym dwustrefowym piecu metodą Bridgamana-Stockbargera. Badania temperaturowe przewodności elektrycznej przeprowadzono w kriostacie z termoregulacją, w temperaturze 77-300 K, przy stabilizacji ±0,1 K. Fotoindukowaną obróbkę laserową monokryształów wykonano przy użyciu 180 ns impulsów drugiej harmonicznej lasera CO2 o długości fali 5,3 μm. Eksperymentalnie wykazano, że z obniżaniem temperatury od 300 do 240 K i od 315 do 270 K przewodnictwo elektryczne monokryształów Tl1−xIn1−xSixSe2 jest wywołane przez wzbudzenia termicznie domieszek z energią aktywacji równą około 0,24 eV i 0,22 eV dla ő = 0,1 i 0,2, odpowiednio. Indukowana optycznie absorpcja osiąga maksimum przy gęstości mocy poniżej 100 mJ/cm2. Stwierdzono, że próbka z x = 0,2 wykazuje większe zmiany absorpcji indukowanej światłem w porównaniu do próbki z x = 0.1. Z dalszym spadkiem temperatury obserwowano monotoniczny spadek energii aktywacji przewodnictwa. Pochodzenie tych efektów jest spowodowane przez wzbudzanie zarówno podsystemu elektronowego jak i fonononowego. Przy niektórych gęstościach mocy wzbudzenia anharmoniczne zaczynają dominować, co w konsekwencji prowadzi do nasycenia indukowanej światłem zależności absorpcji optycznej. Dodatkowo w pracy wyznaczono dla danej temperatury średnią długość skoku R dla stanów zlokalizowanych w pobliżu poziomu Fermiego.