scholarly journals Luminescence Centers in Thin Films of ZnGa2O4

2015 ◽  
Vol 16 (1) ◽  
pp. 74-78 ◽  
Author(s):  
O. M. Bordun ◽  
I. Y. Kukharskyy ◽  
B. O. Bordun
Keyword(s):  
Thin Films ◽  
Energy Level ◽  
Luminescence Band ◽  
Oxygen Vacancies ◽  
Energy Level Diagram ◽  
Electronic Transitions ◽  
Luminescence Spectra ◽  
X Ray ◽  
Luminescence Centers

Photoexcitation spectra and luminescence of thin films of ZnGa2O4 under photo-, cathode and X-ray excitation were investigated. Luminescence spectra were factorized on ultimate constituents using Alentsev-Fock method. Emission bands with maximums at 3.35, 2.85, 2.50 and 2.38 eV were referred to the luminescence at the expense of electronic transitions between 4Т2, 4Т1, 2Е and 4А2 terms in octahedral complexes (GaO6)9–. It was proposed an energy level diagram with corresponding electronic transitions in such structure. Luminescence band with maximum at 1.75 eV is attributed to oxygen vacancies.

scholarly journals Raman Study of Nanocrystalline-Doped Ceria Oxide Thin Films

Coatings ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 432 ◽  
Author(s):  
Nursultan Kainbayev ◽  
Mantas Sriubas ◽  
Darius Virbukas ◽  
Zivile Rutkuniene ◽  
Kristina Bockute ◽  
...  
Keyword(s):  
Thin Films ◽  
Rare Earth ◽  
Cerium Oxide ◽  
Oxygen Vacancies ◽  
Raman Shift ◽  
Size Factor ◽  
Doped Ceria ◽  
X Ray ◽  
Sio2 Substrate ◽  
Lower Frequencies

Samarium-doped ceria (SDC) and gadolinium-doped ceria (GDC) thin films were formed by e-beam vapor deposition on SiO2 substrate, changing the deposition rate and substrate temperature during the deposition. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-Ray spectrometry (EDS) were employed in order to investigate the structure ad morphology of the films. A single Raman peak describing the structure of undoped CeO2 was observed at a frequency of 466 cm−1. Doping of cerium oxide with rare-earth elements shifted the peak to lower frequencies (for Sm—462 cm−1). This shift occurs due to the increased number of oxygen vacancies in doped cerium oxide and it depends on the size and concentration factor of the dopant. It was found that wavenumbers and their intensity differed for the investigated samples, even though the peaks resembled each other in shape. The indicated bands for doped ceria originated as a result of the Raman regime (F2g) of fluorite dioxide associated with the space group (Fm3m). The observed peak‘s position shifting to a lower frequency range demonstrates the symmetric vibrations of oxygen ions around Ce4+ ions in octahedra CeO8. Raman shift to the lower frequencies for the doped samples has two reasons: an increase in oxygen vacancies caused by doping cerium oxide with rare-earth materials and the size factor, i.e., the change in frequency Δω associated with the change in the lattice constant Δa.

scholarly journals EPR Spectroscopy of Different Sol Concentration Synthesized Nanocrystalline-ZnO Thin Films

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Manju Arora ◽  
Rayees A. Zargar ◽  
S. D. Khan
Keyword(s):  
Thin Films ◽  
Oxygen Vacancies ◽  
Film Surface ◽  
Epr Spectra ◽  
Zno Thin Films ◽  
Zno Films ◽  
Zno Film ◽  
Resonance Signal ◽  
X Ray ◽  
Impurity Defects

Nanocrystalline zinc oxide (nc-ZnO) thin films were grown on p-type silicon substrate through spin coating by sol-gel process using different sol concentrations (10 wt.%, 15 wt.%, and 25 wt.%). These films were characterized by high resolution nondestructive X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDS) attachment, and electron paramagnetic resonance (EPR) techniques to understand variations in structural, morphological, and oxygen vacancy with respect to sol concentration. The film surface morphology changes from nanowall to nanorods on increasing sol concentration. EPR spectra revealed the systematic variation from ferromagnetic to paramagnetic nature in these nc-ZnO films. The broad EPR resonance signal arising from the strong dipolar-dipolar interactions among impurity defects present in nc-ZnO film deposited from 10 wt.% sol has been observed and a single strong narrow resonance signal pertaining to oxygen vacancies is obtained in 25 wt.% sol derived nc-ZnO film. The concentrations of impurity defects and oxygen vacancies are evaluated from EPR spectra, necessary for efficient optoelectronic devices development.

Etats Rydberg de NS. Etude du domaine spectral 2400–1750 Å

1976 ◽  
Vol 54 (18) ◽  
pp. 1909-1923 ◽  
Author(s):  
Michel Vervloet ◽  
Alain Jenouvrier
Keyword(s):  
Energy Level ◽  
Relative Position ◽  
Rydberg States ◽  
Energy Level Diagram ◽  
Electronic Transitions ◽  
Complete Analysis ◽  
Molecular Constants ◽  
Π State ◽  
Potential Curves

Five electronic transitions, C2Σ+–X2Π, I2Σ+–X2Π, E2Π–X2Π, J2Σ+–X2Π, and F2Δ–X2Π of NS have been observed in the region 1750–2400 Å. The complete analysis of these transitions has been carried out. The molecular constants of the C2Σ+, E2Π, J2Σ+, and F2Δ Rydberg states are given. Many perturbations in the rotational structures (ν = 1 and 2 of C2Σ+, ν = 0 of E2Π) and predissociations in the levels ν = 0 J2Σ+ and F2Δ are observed. The perturbation in the level ν = 0 of the E2Π state is described, the perturbing level being ν = 11 of the H2Π valence state.The most important results are given in the tables of constants. An energy level diagram and potential curves show the relative position of the different states. All the observed states of NS are finally compared with those of PO.

scholarly journals Some investigations in Röntgen spectra. Part I.─X-ray spark lines

1931 ◽  
Vol 131 (818) ◽  
pp. 633-647 ◽  
Keyword(s):  
Energy Level ◽  
Wave Length ◽  
The State ◽  
Energy Level Diagram ◽  
Selection Rules ◽  
X Ray ◽  
Long Wave ◽  
Chemical Combination ◽  
Close Study ◽  
Principal Lines

As is now well known there are certain lines in Röntgen spectra which cannot be fitted up into the usual energy level diagram even after violating the selection rules ∆ j = ± 1, 0, and ∆1 = ±1. These are called “non-diagram” lines or “spark” lines although the latter designation is somewhat anomalous in as much as the usual diagram lines are, regularly, lines due to transitions in an atom deprived of one of the electrons of the completed groups. They are found on the short as well as on the long wave-length side of the principal diagram lines, and consequently it has been customary to describe them as “satellites” of the principal lines. After their first discovery by Siegbahn and Stenström their number has rapidly grown large. Recently Beuthe has measured the β‴ line for elements V (23) to Y (39) and has also discovered a new line η for some of these elements. The problem of X-ray spark lines is little understood, and it is desirable to study closely the satellites of the principal lines for many elements in the several series. As a first step towards the achievement of this end a close study of Kα and Kβ satellites of the elements Si (14) to Cl (17) was undertaken. The results obtained go to show that the structure of the satellites is complex and that their nature is highly dependent upon the state of chemical combination of the atom which emits them.

scholarly journals Solution-processed CdS quantum dots on TiO2: light-induced electrochemical properties

RSC Advances ◽  
2016 ◽  
Vol 6 (86) ◽  
pp. 83175-83184 ◽  
Author(s):  
Babasaheb R. Sankapal ◽  
Dipak B. Salunkhe ◽  
Sutripto Majumder ◽  
Deepak P. Dubal
Keyword(s):  
Thin Films ◽  
Quantum Dots ◽  
Energy Level ◽  
Electrochemical Properties ◽  
Energy Level Diagram ◽  
Cds Quantum Dots ◽  
Solution Processed

Schematic of CdS-sensitized mesoporous TiO2 nanoparticles thin films along with their energy level diagram.

scholarly journals SPECTROSCOPIC PROPERTIES OF SOLIDIFIED MELTS OF THE EuF3-CeF3-NaCl-KCl SYSTEM

2020 ◽  
Vol 86 (10) ◽  
pp. 120-128
Author(s):  
Viktor Zinchenko ◽  
Oleg Ieriomin ◽  
Valerii Antonovich ◽  
Nataliia Chivireva ◽  
Iryna Stoianova ◽  
...  
Keyword(s):  
Absorption Band ◽  
Luminescence Band ◽  
Diffuse Reflection ◽  
Bathochromic Shift ◽  
Electronic Transitions ◽  
Luminescence Spectra ◽  
Complete Disappearance ◽  
Diffuse Reflection Spectroscopy ◽  
Exchange Reactions ◽  
Salt Melt

The nature of the interaction in the EuF3-CeF3 system in the process of high-temperature (1050 °C) oxidation - reduction reaction was established by the methods of IR transmission spectroscopy, diffuse reflection spectroscopy and fluorescence spectroscopy. Here is a significant bathochromic shift to 480-485 nm band of blue luminescence of Eu(II) - containing phases, due to the 5d–4f electronic transitions, as well as the manifestation of orange-red luminescence of Eu(III) - containing phases due to 4f–4f electronic transitions in the range of 590–690 nm. There is a bathochromic shift of the IR bandwidth in the spectrum of the solidified salt melt as a result of dissolution of the fluoride system. Diffuse reflection spectra reveal changes in the composition of the phases that dissolve in the salt melt due to exchange reactions. The wide absorption band in the UV range gives way to a negative absorption band consisting of two peaks due to luminescence. The almost complete disappearance of the band of 4f–4f transitions in Eu(III) in the near-IR range of the spectrum is evidence of its entire reduction in the chloride melt to Eu(II). The character of the luminescence spectra of solidified salt melts also changes in comparison with the initial sample of the EuF3-CeF3 system, namely, the luminescence band of Ce3+ ions disappears, and the luminescence band of Eu2+ ions at 430–440 nm becomes narrow and highly intensive. The luminescence band of Eu3+ ions in the orange-red region of the spectrum disappears completely. Thus, Eu2+ ions become dominant in the formation of the spectral picture of the solidified salt melt, which is evidence of the completion of the redox process in the system.

Etats de valence de NS dans le domaine 2250–3800 Å

1973 ◽  
Vol 51 (20) ◽  
pp. 2143-2161 ◽  
Author(s):  
Alain Jenouvrier ◽  
Bernard Pascat
Keyword(s):  
Energy Level ◽  
Energy Level Diagram ◽  
Electronic Transitions ◽  
Rotational Analysis ◽  
Molecular Constants ◽  
Potential Curves

Five red-degraded transitions, A2Δ–X2Π, G2Σ−–X2Π, H2Π–X2Π, I2Σ+–X2Π, and B2Π–X2Π of 14N32S, have been observed in the region 2250–3800 Å. The complete rotational analysis of these transitions leads to a coherent attribution of the electronic transitions and reveals many perturbations in the rotational structures. All the levels of the A2Δ state are perturbed and the perturbing state is presumably a [Formula: see text] state.The most important results are given in the tables of molecular constants. An energy level diagram and potential curves show the relative positions of the different observed states.

Effects of Fe and Ni Co-Doping on the Optical Properties of TiO2 Thin Films

2019 ◽  
Vol 19 (01) ◽  
pp. 1850046
Author(s):  
Mahboubeh Yeganeh ◽  
Maliheh Mousavi
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Oxygen Vacancies ◽  
Visible Region ◽  
X Ray Diffraction ◽  
Structural And Optical Properties ◽  
Tio2 Thin Films ◽  
X Ray ◽  
Co Doping ◽  
Uv Visible

In this work, the effects of Fe/Ni co-doping on structural and optical properties of TiO2 thin films were investigated by the X-ray diffraction, scanning electron microscope and UV-visible spectroscopy. The optical properties of transmittance, extinction coefficient, refractive index, real and imaginary parts of dielectric constant of the thin films, prepared by spray pyrolysis, revealed that the absorption in visible region increases due to the influence of Fe/Ni co-doping. The widening of the gap energies is observed as a result of doping. The increased optical gap as a consequence of doping can be explained by decreasing the size of nanoparticles, as confirmed by SEM and increasing the formation of oxygen vacancies as a result of Ni[Formula: see text] substitution to Ti[Formula: see text] and appearance of the Burstein–Moss effect.

scholarly journals Significantly reduced leakage current density in Mn-doped BiFeO3 thin films deposited using spin coating technique

2021 ◽  
Vol 2070 (1) ◽  
pp. 012088
Author(s):  
Waseem Ahmad Wani ◽  
Nilofar Naaz ◽  
B. Harihara Venkataraman ◽  
Souvik Kundu ◽  
Kannan Ramaswamy
Keyword(s):  
Thin Films ◽  
Leakage Current ◽  
Leakage Current Density ◽  
Current Density ◽  
Indium Tin Oxide ◽  
Oxygen Vacancies ◽  
Oxide Glass ◽  
Mn Doping ◽  
X Ray ◽  
Mn Doped

Abstract BiFeO3 (BFO) and Mn-doped BFO thin films are prepared on indium tin oxide/glass substrates using wet chemical deposition technique. The role of Mn defects (3% to 10%) on the leakage current density and other physical properties of BFO thin film devices is investigated. The X-ray diffraction patterns confirm the single-phase formation of rhombohedrally distorted BFO thin films. The scanning electron microscopy images approve uniform and crack-free film depositions, which is of great importance to the practical device applications of such materials. The oxidation states are determined by X-ray photoelectron spectroscopy (XPS). These XPS results reveal the presence of multiple valence states of Fe ions (Fe2+, Fe3+) and Mn (Mn3+, Mn4+) ions, which play a decisive role in determining the leakage current density. However, the Mn-doping at the Fe site in BFO reduces oxygen vacancies and Fe2+ states, hence suppressing the leakage current density. The leakage current density is reduced by three orders of magnitude (10−4 – 10−7) A/cm2, upon Mn-doping as clearly demonstrated by J-V characteristics. These results indicate that the primary contributors to the conduction in BFO based thin films are oxygen vacancies and the Fe2+ states in these devices.

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