Search results

1

X-Ray Photoelectron Spectroscopy and Optical Reflectivity Studies of Si Surfaces Prepared by Chemical Etching

100%

Iwanowski R. J., Sobczak J. W., Kowalski B. J.

Acta Physica Polonica A

|

1994

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vol. 86

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issue 5

825-830

EN

Complementary X-ray photoelectron spectroscopy and optical reflectivity studies of crystalline Si(111) surfaces prepared by two different wet chemical etching processes were performed. These included aqueous HF solution etch or diluted CP-4 bath. Optical reflectivity spectra of Si surfaces, measured in the range 3.7-11 eV, were found strongly dependent on the applied etching process. Analysis of the core level X-ray photoelectron spectroscopy data has shown similarity of the surface structure, irrespectively of the etching procedure. Finally, comparison of optical reflectivity and valence band X-ray photoelectron spectra revealed a qualitative correlation between them indicating dominant influence of the bulk (here, the subsurface region containing polishing-induced defects) in the case studied. This paper is the first one which presents correlations between optical reflectivity and X-ray photoelectron spectroscopy data for Si and thus illustrates a bulk sensitivity of both techniques considered.

2

Ab Initio Study of Electronic Structure and Magnetic Properties of Gd(Ni_{1-x}Fe_x)_3 Alloys

100%

Deniszczyk J., Woźniakowski A., Borgieł W.

Acta Physica Polonica A

|

2012

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vol. 121

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issue 5-6

1156-1158

EN

We present the ab initio investigations of the electronic and magnetic properties of magnetocaloric Gd(Ni_{1-x}Fe_x)_3 alloys. To simulate fractional concentrations the supercell approach was implemented and different configurations of iron atoms were considered. Energetical analysis of site preference and magnetic order was performed. The concentration dependence of the averaged total and local magnetic moments and of the valence band photoemission spectra are presented and discussed in reference to experimental data.

3

Angle-Resolved Photoelectron Spectroscopy on CdTe(100) c(2×2)

100%

Gawlik K., Brügmann J., Harm S., Manzke R., Skibowski M., Kowalski B., Orłowski B.

Acta Physica Polonica A

|

1993

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vol. 84

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issue 6

1093-1099

EN

The CdTe(100) c(2×2) surface prepared by ion bombardment and annealing was investigated by angle-resolved photoemission spectroscopy using synchrotron radiation with photon energies between 8.5 eV and 32 eV. The bulk band structure was determined along the ΓΔX-direction normal to the surface measuring energy-distribution curves. The results are compared with a theoretical valence band structure assuming free-electron-like final states in connection with k-conservation. For further comparison we calculated the final states by the pseudopotential method and analyzed the results in form of structure plots. In this way, most of the dispersing maxima in the normal emission spectra can be explained. For this mode of photoelectron spectroscopy the resulting dispersion must be due to the component of the Bloch wave vector normal to the surface, k_{⊥}, keeping surface related structures at a fixed binding energy position E_{b}. The lack of dispersion for five structures along ΓΔX gives experimental evidence for their surface origin.

4

Electronic Structure of Sm(Ni_{1-x}Co_{x})₃ Alloys - XPS and ab initio Study

100%

Majtyka A., Sikora M., Blachiński D., Chełkowska G., Deniszczyk J.

Acta Physica Polonica A

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2018

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vol. 133

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issue 3

673-675

EN

The band structure investigations for Sm(Ni_{1-x}Co_{x})₃ alloys by means of X-ray photoelectron spectroscopy (XPS) and an ab initio density functional theory (DFT) calculations are presented. The aim was to determine an effect of Ni/Co substitution on the electronic structure of the alloys. Investigations have shown that the Ni/Co substitution results in a reconstruction of the valence band (VB), especially the intensity near the Fermi level decreases with Co content. An ab initio simulated XPS VB spectra agree qualitatively with experimental ones with the exception of the Sm-4f sub-spectra where the multiplet decomposition is observed. Calculations shown that variation of magnetization in Sm(Ni_{1-x}Co_{x})₃ is driven mainly by the Ni/Co-3d and Sm-5d states polarization and increases linearly with rising Co content.

5

Effect of Alloying on Magnetism and Electronic Structure of Gd(In_{1-x}Snₓ)₃ System - ab initio Study

100%

Deniszczyk J., Bajorek A., Chełkowska G., Zipper E.

Acta Physica Polonica A

|

2015

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vol. 127

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issue 2

427-429

EN

We present the results of ab initio study of electronic and magnetic properties of Gd(In_{1-x}Snₓ)₃ alloys carried out with the use of FP-LAPW method. Our precise ab initio calculations for the first time uniquelly confirmed experimentally based predictions that the ground state magnetic structure of the alloys is antiferromagnetic and that upon the In/Sn substitution the magnetic structure undergo transition, changing the antiferromagnetic ordering from the (π00)-type for the GdSn₃ compound to the (ππ0)-type for the GdIn₃ one. Moreover, calculations gave an explanation of the oscillatory variation of density of states at Fermi level indicated by XPS measurements.

6

X-Ray Photoelectron Study of Yb-Doped InP

100%

Iwanowski R. J., Sobczak J. W., Kaliński Z.

Acta Physica Polonica A

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1997

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vol. 91

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issue 4

809-813

EN

X-ray photoelectron spectra of core levels are reported for InP:Yb. Crystalline InP, doped with Yb to a level of 0.5 at.%, was grown by the synthesized solute diffusion method. An analysis of the core-level spectra of the constituent components, i.e. In 3d_{5/2} and P 2p, revealed a minor influence of the surface oxide species, mainly in the phosphate-like form. The spectrum of the Yb 4d core level was also recorded. The energy of the Yb 4d_{3/2} peak was found identical to that in Yb metal, whereas the 4d_{5/2} peak was found to be shifted to higher binding energies. This effect was found comparable to the case of advanced oxidation of Yb thus confirming its high reactivity, even as a bulk dopant. The data give also a rare experimental example of detection of bulk dopant atoms in a semiconductor matrix by X-ray photoelectron spectroscopy at the limit of detectability.

7

Layered Semiconductors and Related Systems

80%

Starnberg H.

Acta Physica Polonica A

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2001

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vol. 100

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issue 3

301-318

EN

The general properties of the layered transition metal dichalcogenides and the possibility to modify these materials by intercalation are reviewed. Examples are given of experimental results obtained by using angle-resolved photoelectron spectroscopy and very-low-energy electron diffraction. The possibility to use layered semiconductors as model systems in studies of e.g. Schottky barriers and surface photovoltage is exemplified by the Rb/WSe_2 system. Attention is also paid to the use of van der Waals epitaxy in interface studies, and its possible practical applications. The potential of layered semiconductors like WSe_2 in solar cell applications is also mentioned.

8

Electronic Structure of TmPdIn

80%

Penc B., Kurleto R., Goraus J., Starowicz P., Szytuła A.

Acta Physica Polonica A

|

2016

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vol. 129

|

issue 6

1184-1186

EN

Electronic structure of a ternary TmPdIn compound, which crystallizes in the hexagonal ZrNiAl-type structure, was studied by X-ray photoemission spectroscopy and ultraviolet photoemission spectroscopy. Density of states in the valence band was calculated by means of the augmented plane wave/local orbital method based on density functional theory. The results showed that the valence band is formed mainly of Tm 4f and Pd 4d states. In the ultraviolet photoemission spectra one can distinguish Pd 4d maximum and Tm 4f multiplet peaks, which are displaced with respect to those of pure Tm.

9

Analysis of Optical Radiation Generated by Electrical Discharges on Support Insulator

80%

Frącz P., Boczar T., Zmarzły D., Szczyrba T.

Acta Physica Polonica A

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2013

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vol. 124

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issue 3

413-416

EN

Subject of the paper concerns determination of the feasibility and indication of the application scope of optical spectroscopy methods in the diagnosis of high-voltage insulators. Results of measurements of optical radiation emitted by partial and complete electrical discharges occurring on a support insulator model placed in air are presented in the paper. Registration was performed using a spectrophotometer, enabling for measurement of optical radiation in the range from 200 to 1800 nm. The primary objective of the laboratory tests was to evaluate the impact of supply voltage changes in the range from 0 to 60 kV on the intensity and spectral character of the optical radiation emitted by electric discharges generated on the porcelain insulation surface of the support insulator. In the scope of studies analyzes of the effects of voltage changes on the obtained spectral wave forms were performed, whereby voltage increase and reduction was examined separately. Additionally, measurements and analyzes carried out included impact estimation of the time period as the voltage was applied to the high-voltage electrodes on the course of optical phenomena related to the generation of electrical discharges.

10

Electronic States of UNi_2 from Photoemission Spectroscopy

80%

Zalecki R., Kołodziejczyk A., Kim-Ngan N., Adamska A., Kowalczyk A., Toliński T., Mihalik M.

Acta Physica Polonica A

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2008

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vol. 113

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issue 1

407-412

EN

We measured the angle-resolved ultraviolet and X-ray photoemission spectra of UNi_2 single crystal. The valence band angle-resolved ultraviolet photoemission spectra were compared to the accessible band structure calculations. For UNi_2 the lowest binding energy strong emission at about -0.1 eV comes from U 5f states and overlaps with the Fermi edge. A small feature at -0.6 eV was ascribed also to U 5f electrons with more localised character. The higher-energy two-peak structure at about -1.2 eV and -2.1 eV comes from Ni 3d states. X-ray photoemission spectroscopy shows the standard two-line spin-orbit splitting of the Ni 2p states and of the U 4f states. Some hybridisation of the Ni 3d and U 5f state was observed in the spectra. The pronounced satellites to the Ni 2p and 3p states, associated with the on-site Coulomb repulsion and other electron correlation energies, were observed.

11

MBE Growth and Properties of GaMnAs(100) Films

80%

Sadowski J., Domagała J., Bąk- Misiuk J., Świątek K., Kanski J., Ilver L., Oscarsson H.

Acta Physica Polonica A

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1998

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vol. 94

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issue 3

509-513

EN

We present here the results of measurements of structural and electronic properties of GaMnAs - a new diluted magnetic semiconductor system. This ternary III-V-Mn compound with the Mn content as high as 7% was obtained for the first time (by means of molecular beam epitaxial growth) by Ohno, Munekata et al. and the studies of its properties are not completed until now. We did the high resolution X-ray diffraction investigations and photoemission measurements of the samples with Mn content varied from about 0.1% up to 5%. The crystalline perfection of the ternary GaMnAs compound is very high - full width at half maximum of GaMnAs (400) Bragg reflections are of order of 50 arcseconds and the layers are fully strained to the GaAs(100) substrate. In photoemission experiments we traced the contribution of Mn 3d states to the band structure of GaMnAs ternary compound.

12

Electronic Structure of Y_{3}Al_{5}O_{12}:V Single Crystals, Comparison with Sintered Ceramics

80%

Kruczek M., Talik E., Kusz J., Sakowska H., Świrkowicz M., Węglarz H.

Acta Physica Polonica A

|

2009

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vol. 115

|

issue 1

209-212

EN

Y_{3}Al_{5}O_{12} (YAG) single crystals doped with vanadium ions (V^{3+}) were obtained by the Czochralski method. The X-ray photoelectron spectra of YAG:V annealed in reducing atmospheres: H_{2}, vacuum and H_{2} + vacuum are presented and compared with the spectra of the YAG ceramics. The X-ray photoelectron spectra showed that the vanadium dopant concentration in YAG:V crystals is lower than a nominal one. For the "as grown" YAG:2.8at.%V crystal vanadium exists in the mixed valence state. The increase in lattice parameters for the samples annealed in hydrogen was found.

13

Photoemission Study of the Electronic Structure of Semiconducting Compounds

80%

Fujimori A., Okabayashi J., Mamiya K.

Acta Physica Polonica A

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1999

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vol. 96

|

issue 5

525-533

EN

We review how the electronic structure of semiconducting compounds is revealed by photoemission spectroscopy. Angle-resolved photoemission spectroscopy is used to study band dispersions and the photon-energy dependence of spectral line shapes is utilized to study atomic orbital origins of the electronic states, namely, the partial density of states. We focus on recent development in the studies of diluted magnetic semiconductors as well as other magnetic semiconductors, in which interaction between the relatively localized transition-metal d states and the extended sp band states plays a key role in characterizing their unique magnetic, transport, and optical properties.

14

Analysis of Interference Signals Generated by Vibroacoustic Vibrations of Transformer Cores

80%

Boczar T., Borucki S., Cichoń A.

Acta Physica Polonica A

|

2014

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vol. 125

|

issue 6

1355-1359

EN

The article deals with the subject matter referring to the interference that may accompany measurements of vibroacoustic signals, generated by electric power transformers, taken by using the acoustic emission method under industrial conditions. Paper concerns measurement and analysis of internal, acoustic type disturbances, including the magnetostrictive vibrations of plate sets within the transformer core, caused by changes in the magnetic flux. Paper presents measurement results of acoustic interfering signals and results of analyses made in the frequency and time-frequency domains. Power spectral density, MUSIC pseudospectra, two- and three-dimensional short time Fourier transform spectrograms, continuous wavelet transform scalograms, discrete wavelet transform, and quantities of energy transferred are included in the paper.

15

Analysis of Optical Radiation Generated by Partial Discharges on Insulators

80%

Frącz P., Boczar T., Borucki S.

Acta Physica Polonica A

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2014

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vol. 125

|

issue 6

1360-1367

EN

Results of measurements of optical radiation emitted by partial and complete electrical discharges occurring on a bushing insulator model placed in air are presented in the article. Registration was performed using a spectrophotometer, enabling for measurement of optical radiation in the range from 270 to 1700 nm. Detailed characteristics of spectrophotometer are presented in our previous paper. The primary objective of the laboratory tests was to evaluate the impact of supply voltage changes in the range from 0 to 0.99 U_{b} (breakdown voltage) on the intensity and spectral character of the optical radiation emitted by partial discharges generated on the porcelain insulation surface of the bushing insulator. In the scope of studies analyzes of the effects of voltage changes on the obtained spectral waveforms were performed, whereby voltage increase and reduction was examined separately. Additionally, measurements and analyzes carried out included impact estimation of the time period as the voltage was applied to the high-voltage electrodes on the course of optical phenomena related to the generation of partial discharges.

16

Temperature Dependence of Photofield Emission from Tungsten ⟨001⟩ Direction

80%

Radoń T., Jaskólka S.

Acta Physica Polonica A

|

1996

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vol. 89

|

issue 5-6

665-668

EN

The existence of a minimum lying by 0.2 eV above the Fermi level, in the band structure of the ⟨001⟩ direction of tungsten, has been confirmed at temperatures of 600÷800 K of the emitter. With increasing temperature a slight rise of the Fermi level in relation to the band structure has been observed.

17

Analysis of 4f Level in Samarium-Rich MBE Grown CdSmTe Sample

80%

Szamota-Sadowska K., Gołacki Z., Orłowski B., Boyn R., Johnson R.

Acta Physica Polonica A

|

1998

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vol. 94

|

issue 3

560-564

EN

Electronic states of 4f samarium ions were investigated by photoemission spectroscopy in samarium-rich CdSmTe sample obtained by MBE. The photon energy of synchrotron radiation allowed to investigate Fano-type resonance and antiresonance. The energy distribution curve spectra were attributed to the Sm 4d-4f transition. The shape of the constant initial states spectra was compared with this one obtained for atomic samarium.

18

Resonant Photoemission Study οf 4f Electrons on the Surface οf Semiconductors

80%

Orłowski B., Kowalski B., Pietrzyk M., Buczko R.

Acta Physica Polonica A

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2008

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vol. 114

|

issue S

S-103-S-114

EN

The contribution of 4f electrons to the electronic structure of the semiconductor clean surface caused by the surface doping of it by rare-earth metal atoms (Eu, Sm) will be presented. The surface doping was performed by the controlled, sequential deposition of the rare-earth metal atoms on the clean surface in UHV conditions (Sm on GaN or CdTe) or by the doping of the layer volume of (EuGd)Te. After each deposition or surface treatment the synchrotron radiation was used to measure in situ the resonant photoemission spectra (the Fano type resonance) to study the contribution of 4f electrons of divalent and trivalent Sm and Eu ions to the valence band electronic structure of created sample. The first stages of the metal atoms deposition lead to the surface doping. Further metal atoms deposition leads to the growth of the metallic islands on the surface and causes the appearance of the sharp metallic Fermi edge in the energy distribution curves. Proper coverage and annealing of the sample surface with metal atoms leads to the diffusion of the metal atoms into the sample and results in an increase in the crystal doping and decrease in the metallic islands contribution to the measured spectra. As a result, the new electronic structure of the valence band can be created and investigated in situ.

19

Electronic States of Collosal Magnetoresistive Manganites La_{0.67}Pb_{0.33}Mn_{1-x}Fe_{x}O_{3} from Photoemission Spectroscopy

80%

Kowalik M., Zalecki R., Kołodziejczyk A.

Acta Physica Polonica A

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2010

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vol. 117

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issue 2

277-280

EN

The electron photoemission spectra of valence bands and core-level states of manganese perovskite La_{0.67}Pb_{0.33}(Mn_{1-x}Fe_{x})O_{3} with x = 0, 0.01, 0.03, 0.06, 0.10 and 0.15 were measured by the X-ray and Ultraviolet Photoemission Spectroscopy (XPS and UPS) below and above the metal-insulator transition. From analysis of the Mn 2p core-level spectra the ratio Mn^{3+}/Mn^{4+} was calculated as a function of the iron content. Comparison of the valence band spectrum with band structure calculations and with the high-resolution spectra measured at synchrotron radiation for Ca-, Ba- and Ce- substituted manganites revealed the strong hybridisation of Mn 3d and of O 2p states between -3 eV and -7 eV, and no estimated oxygen states between 0 eV and -2 eV where the Mn-3d states play a predominant role. The composition dependent insulating energy gaps were measured at room temperature. Reasons for the behaviour were discussed taking into account previous analysis of XPS/UPS spectra of other manganese perovskites.

20

Results of Optical Signals Analyses Emitted by Electrical Discharges Recorded with UV Camera

80%

Frącz P., Boczar T., Borucki S., Cichoń A., Zmarzły D.

Acta Physica Polonica A

|

2012

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vol. 122

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issue 5

814-817

EN

In the article results of measurements and analyses of the optical signals emitted by electrical surface partial discharges occurring on bushing and post insulators, recorded with UV camera during tests under laboratory conditions are presented. The carried out research was to determine the effect of the distance between the insulator's electrodes and the voltage value on the number of partial discharges.

Refine search results

X-Ray Photoelectron Spectroscopy and Optical Reflectivity Studies of Si Surfaces Prepared by Chemical Etching

Ab Initio Study of Electronic Structure and Magnetic Properties of Gd(Ni_{1-x}Fe_x)_3 Alloys

Angle-Resolved Photoelectron Spectroscopy on CdTe(100) c(2×2)

Electronic Structure of Sm(Ni_{1-x}Co_{x})₃ Alloys - XPS and ab initio Study

Effect of Alloying on Magnetism and Electronic Structure of Gd(In_{1-x}Snₓ)₃ System - ab initio Study

X-Ray Photoelectron Study of Yb-Doped InP

Layered Semiconductors and Related Systems

Electronic Structure of TmPdIn

Analysis of Optical Radiation Generated by Electrical Discharges on Support Insulator

Electronic States of UNi_2 from Photoemission Spectroscopy

MBE Growth and Properties of GaMnAs(100) Films

Electronic Structure of Y_{3}Al_{5}O_{12}:V Single Crystals, Comparison with Sintered Ceramics

Photoemission Study of the Electronic Structure of Semiconducting Compounds

Analysis of Interference Signals Generated by Vibroacoustic Vibrations of Transformer Cores

Analysis of Optical Radiation Generated by Partial Discharges on Insulators

Temperature Dependence of Photofield Emission from Tungsten ⟨001⟩ Direction

Analysis of 4f Level in Samarium-Rich MBE Grown CdSmTe Sample

Resonant Photoemission Study οf 4f Electrons on the Surface οf Semiconductors

Electronic States of Collosal Magnetoresistive Manganites La_{0.67}Pb_{0.33}Mn_{1-x}Fe_{x}O_{3} from Photoemission Spectroscopy

Results of Optical Signals Analyses Emitted by Electrical Discharges Recorded with UV Camera