scholarly journals Диссоциативная рекомбинация в послесвечении барьерного разряда в неоне низкого давления. Заселение атомов конфигурации 2p-=SUP=-5-=/SUP=-3d

2021 ◽  
Vol 129 (11) ◽  
pp. 1360
Author(s):  
В.А. Иванов
Keyword(s):  
Near Infrared ◽  
Barrier Discharge ◽  
Cylindrical Tube ◽  
Dissociative Recombination ◽  
Infrared Region ◽  
Molecular Ions ◽  
Inelastic Collisions ◽  
Ultraviolet Region ◽  
Excited Atoms ◽  
Near Ultraviolet

The decaying neon plasma produced by the dielectric barrier discharge (DBD) in a cylindrical tube at a pressure of 0.1–40 Torr has been spectroscopically investigated to analyze the dissociative recombination (DR) of molecular ions with electrons as a mechanism for the formation of excited atoms. It is shown that, at the electron density in the afterglow less than 5•1010 cm-3 the DR is the dominant source of population of 3d levels at pressures PNe ≥ 0.6 Torr. At lower pressures, the optical properties of the decaying plasma are formed to a greater extent by the collisional-radiative recombination of Ne+ ions. A significant variation of the relative intensities of the 3d -> 3p transition lines in the afterglow with a change in gas pressure was found, reflecting the effect of inelastic collisions on the formation of the spectrum of decaying plasma in the near infrared region. From measurements carried out at a pressure of 0.6 Torr, the relative values of the partial DR coefficients for the 3dj levels of the neon atom were found. Comparison of these data with measurements in the near ultraviolet region, containing the lines of 4p -> 3s transitions, indicates the need to take into account the cascade 4p -> 3d transitions to correctly solve the problem of the final products of dissociative recombination.

scholarly journals Гелиевое послесвечение без метастабильных частиц

2019 ◽  
Vol 127 (12) ◽  
pp. 890
Author(s):  
В.А. Иванов ◽  
Ю.Э. Скобло
Keyword(s):  
Radiative Recombination ◽  
Barrier Discharge ◽  
Early Stage ◽  
Dissociative Recombination ◽  
Molecular Ions ◽  
Low Density ◽  
Atomic Ions ◽  
Excited Atoms ◽  
Small Admixture ◽  
Vibrational Kinetics

The results of a spectroscopic study of the afterglow of a pulsed barrier discharge in helium with a small admixture of neon, which creates a plasma with a low density of metastable particles, are discussed. The early stage of the afterglow of such a discharge is free of processes involving metastables and has a purely recombination nature. The characteristics of the afterglow are interpreted on the basis of the model taking into account vibrational kinetics and dissociative recombination of molecular ions. A comparison of experimental data and model solutions for collisional-radiative recombination of atomic ions and dissociative recombination leads to the conclusion in favor of the latter process as a source of the excited atoms.

scholarly journals Variations in color and reflectance on the surface of asteroid (101955) Bennu

Science ◽  
2020 ◽  
Vol 370 (6517) ◽  
pp. eabc3660 ◽  
Author(s):  
D. N. DellaGiustina ◽  
K. N. Burke ◽  
K. J. Walsh ◽  
P. H. Smith ◽  
D. R. Golish ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Region ◽  
Color Variation ◽  
Ultraviolet Region ◽  
Multispectral Images ◽  
Geologic History ◽  
Color Changes ◽  
Near Ultraviolet ◽  
History Of ◽  
Exposure Ages

Visible-wavelength color and reflectance provide information about the geologic history of planetary surfaces. Here we present multispectral images (0.44 to 0.89 micrometers) of near-Earth asteroid (101955) Bennu. The surface has variable colors overlain on a moderately blue global terrain. Two primary boulder types are distinguishable by their reflectance and texture. Space weathering of Bennu surface materials does not simply progress from red to blue (or vice versa). Instead, freshly exposed, redder surfaces initially brighten in the near-ultraviolet region (i.e., become bluer at shorter wavelengths), then brighten in the visible to near-infrared region, leading to Bennu’s moderately blue average color. Craters indicate that the time scale of these color changes is ~105 years. We attribute the reflectance and color variation to a combination of primordial heterogeneity and varying exposure ages.

scholarly journals Interface engineering for gain perovskite photodetectors with extremely high external quantum efficiency

RSC Advances ◽  
2020 ◽  
Vol 10 (54) ◽  
pp. 32976-32983
Author(s):  
Xinyu Zhao ◽  
Lixiang Huang ◽  
Yukun Wang ◽  
Xinglin Zhu ◽  
Lei Li ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
Near Infrared ◽  
Infrared Region ◽  
High Gain ◽  
Ultraviolet Region ◽  
Interface Engineering ◽  
High Responsivity ◽  
Near Infrared Region

Efficient CH3NH3PbI3 photodetectors (PDs) with an extremely high gain of the maximum external quantum efficiency (EQE) of 140 000% within the ultraviolet region to the near infrared region (NIR) and an extremely high responsivity (R) under a low bias of −5 V were successfully fabricated.

Fabrication of MgIn2O4 Thin Films With Low Resistivity on MgO (100) Surface by PLD Method

2000 ◽  
Vol 623 ◽  
Author(s):  
R. Noshiro ◽  
K. Ueda ◽  
H. Hosono ◽  
H. Kawazoe
Keyword(s):  
Thin Films ◽  
Epitaxial Growth ◽  
Near Infrared ◽  
Infrared Region ◽  
Ultraviolet Region ◽  
Low Oxygen ◽  
Electron Microscopic ◽  
Lattice Image ◽  
Transmission Electron ◽  
Electron Carriers

AbstractThin films of MgIn2O4 spinel, which is a recently discovered TCO material, were deposited on MgO (100) surface by PLD. The thin films were prepared under low oxygen partial pressure to enhance formation of oxygen vacancies, from which carrier electrons were generated. X-ray analyses and AFM observations suggest epitaxial growth of the grains with diameter of 100∼200nm. The grains showed strong orientations both along the normal of the thin film and in plane. Epitaxial growth of the spinel was also confirmed by high-resolution transmission electron microscopic observations. The lattice image of the interface region suggests formation of structural imperfections such as dislocations, grain boundaries and amorphous phase in significant fraction. Strong optical absorption due to electron carriers was detected in near infrared region. Very large Burnstein-Moss shift was observed in ultraviolet region, and the optical band gap was estimated to be 4.3eV. DC conductivity observed was 4.5×103Scm−1, which is the highest value reported for the material so far. Concentration and Hall mobility of carrier electrons were found to be 2.1×1021cm−3 and 14cm2V−1s−1, respectively.

scholarly journals Broadband photon absorption in self-assembled networks of multiphase oxides of titanium

2021 ◽  
Author(s):  
Pooja Thakur
Keyword(s):  
Near Infrared ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Solar Spectrum ◽  
Infrared Region ◽  
Single Step ◽  
Photon Absorption ◽  
Visible Range ◽  
Ultraviolet Region ◽  
Self Assembled

Titanium -dioxide (TiO2) has garnered immense interest as a potential photon absorber after the discovery of its photocatalytic properties. However, its absorption is limited to the ultraviolet region of the solar spectrum. Despite numerous efforts being made, the challenge to extend its absorption capability to the entire visible and near infrared region (vis-NIR) still exists, which together constitute about 90 % of the solar spectrum. In this dissertation, a multiphase nano TiOx network, rich in defects and oxygen vacancies, has been presented which can absorb photons over a broader range of the solar spectrum. Experimental studies were initially conducted to phase functionalise titanium towards enhanced photon absorption via a single step, ultrashort laser pulse material interaction process. This phase functionalised titanium, characterised to be uniquely composed of multiple oxide phases of titanium, can effectively absorb photons in the vis-NIR region. Using the above study as a template, a complex three-dimensional self-assembled nano network composed of similar multiphase titanium oxides, was then synthesised. Free of any external dopants, it exhibits a remarkable absorption of photons ranging from 300-1000 nm. To further improve the absorptive properties of this ‘multiphase nano TiOx network’, particularly in the lower visible range, the phenomenon of Surface Plasmon Resonance was utilised via its hybridisation with gold and gold/palladium alloy. This successfully resulted in further optimisation of its absorption. The final study of the multiphase nano TiOx was done to understand the fundamental physics behind its broadened photon absorptive behaviour. The condition of synthesis was varied by introducing various contrasting plasma environments. Pronounced disorders and oxygen defects of varying degrees within the crystalline structure were observed. The enhanced and broadened absorption spectrum achieved was attributed to such defects and disorders. The research done in this thesis demonstrates a unique nanomaterial based on multiple oxides phases of titanium that is capable of absorbing photons both in the visible and NIR regions. The contribution made towards the synthesis, investigation and subsequent manipulation of the self-assembled multiphase nano TiOx network can thus be exploited in various photon harvesting applications like photovoltaics and photo catalysis, where such a broadband photon absorption is desirable.

scholarly journals Temperature-Dependent Optical Properties of Graphene on Si and SiO2/Si Substrates

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 358
Author(s):  
Sisi Wu ◽  
Lingyu Wan ◽  
Liangmin Wei ◽  
Devki N. Talwar ◽  
Kaiyan He ◽  
...  
Keyword(s):  
Optical Properties ◽  
Optical Constants ◽  
Near Infrared ◽  
Infrared Region ◽  
Peak Position ◽  
Monolayer Graphene ◽  
Ultraviolet Region ◽  
Si Substrate ◽  
Temperature Dependent ◽  
Si Substrates

Systematic investigations are performed to understand the temperature-dependent optical properties of graphene on Si and SiO2/Si substrates by using a variable angle spectroscopic ellipsometry. The optical constants of graphene have revealed changes with the substrate and temperature. While the optical refractive index (n) of monolayer graphene on Si exhibited clear anomalous dispersions in the visible and near-infrared region (400–1200 nm), the modification is moderate for graphene on SiO2/Si substrate. Two graphene sheets have shown a pronounced absorption in the ultraviolet region with peak position related to the Van Hove singularity in the density of states. By increasing the temperature from 300 K to 500 K, for monolayer graphene on Si, the n value is gradually increased while k decreased. However, the optical constants [n, k] of monolayer graphene on SiO2/Si exhibited unpredictable wave variations. In the wavelength range of 400–1200 nm, an experiential formula of a like-Sellmeier equation is found well suited for describing the dispersions of graphene on Si and SiO2/Si substrates.

scholarly journals Development of Circularly Polarized Luminescence (CPL) Peptides Containing Pyrenylalanines and 2-Aminoisobutyric Acid

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1550
Author(s):  
Yuki Mimura ◽  
Yuki Motomura ◽  
Mizuki Kitamatsu ◽  
Yoshitane Imai
Keyword(s):  
Near Infrared ◽  
Infrared Region ◽  
Aggregate Formation ◽  
Peptide Backbone ◽  
Circularly Polarized ◽  
Aminoisobutyric Acid ◽  
Near Ultraviolet ◽  
Organic Luminophores ◽  
Circularly Polarized Luminescence ◽  
Polarized Luminescence

Chiral organic and organometallic luminophores that possess circularly polarized luminescence (CPL) properties in the near-ultraviolet to near-infrared region have several useful applications. However, the CPL properties are subject to inherent factors of the compounds; to date, studies on the CPL properties influenced by amino acids and peptides are scarce. Consequently, we developed peptide-pyrene organic luminophores exhibiting various CPL properties. It is conceivable that the peptide-pyrene organic luminophores can be obtained as aggregates when dissolved in a solution. It is also possible that the formation of aggregates makes it difficult to accurately examine the CPL of the peptide in the solution. This study showed that the introduction of sterically hindered 2-aminoisobutyric acid (Aib) units into the peptide backbone inhibits aggregate formation. The resulting luminophores exhibit CPL properties owing to the presence of pyrene units. The results of this study can form a basis for the design of future materials that use peptide-pyrene organic luminophores.

scholarly journals Broadband photon absorption in self-assembled networks of multiphase oxides of titanium

2021 ◽  
Author(s):  
Pooja Thakur
Keyword(s):  
Near Infrared ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Solar Spectrum ◽  
Infrared Region ◽  
Single Step ◽  
Photon Absorption ◽  
Visible Range ◽  
Ultraviolet Region ◽  
Self Assembled

Titanium -dioxide (TiO2) has garnered immense interest as a potential photon absorber after the discovery of its photocatalytic properties. However, its absorption is limited to the ultraviolet region of the solar spectrum. Despite numerous efforts being made, the challenge to extend its absorption capability to the entire visible and near infrared region (vis-NIR) still exists, which together constitute about 90 % of the solar spectrum. In this dissertation, a multiphase nano TiOx network, rich in defects and oxygen vacancies, has been presented which can absorb photons over a broader range of the solar spectrum. Experimental studies were initially conducted to phase functionalise titanium towards enhanced photon absorption via a single step, ultrashort laser pulse material interaction process. This phase functionalised titanium, characterised to be uniquely composed of multiple oxide phases of titanium, can effectively absorb photons in the vis-NIR region. Using the above study as a template, a complex three-dimensional self-assembled nano network composed of similar multiphase titanium oxides, was then synthesised. Free of any external dopants, it exhibits a remarkable absorption of photons ranging from 300-1000 nm. To further improve the absorptive properties of this ‘multiphase nano TiOx network’, particularly in the lower visible range, the phenomenon of Surface Plasmon Resonance was utilised via its hybridisation with gold and gold/palladium alloy. This successfully resulted in further optimisation of its absorption. The final study of the multiphase nano TiOx was done to understand the fundamental physics behind its broadened photon absorptive behaviour. The condition of synthesis was varied by introducing various contrasting plasma environments. Pronounced disorders and oxygen defects of varying degrees within the crystalline structure were observed. The enhanced and broadened absorption spectrum achieved was attributed to such defects and disorders. The research done in this thesis demonstrates a unique nanomaterial based on multiple oxides phases of titanium that is capable of absorbing photons both in the visible and NIR regions. The contribution made towards the synthesis, investigation and subsequent manipulation of the self-assembled multiphase nano TiOx network can thus be exploited in various photon harvesting applications like photovoltaics and photo catalysis, where such a broadband photon absorption is desirable.

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