Photon Energy Region Research Articles

The electronic spectra of trifluoroacetic acid and chlorodifluoroacetic acid in the 4.5 – 10.8 eV photon energy region

The electronic spectra of trifluoroacetic acid and chlorodifluoroacetic acid in the 4.5 – 10.8 eV photon energy region

The Near‐Infrared‐II Optical Tuning and Electronic Engineering of MoS2 Bilayers Doped by Halogen Elements

The improvement of optical absorption behavior of the second near‐infrared region (NIR‐II, 1000–1350 nm) based on new function materials is significant for the development of biomedicine and optical imaging. Therefore, the electronic structures and optical absorption of 2H phase MoS2 doped by F, Cl, Br, and I atoms with various doping concentrations are calculated, results show that halogen elements introduced extra transition allowed bands which is about 1.0 eV wide to 2H‐MoS2, and the increasing of impurity concentration can trigger strong spin splits. The transformation of electronic structures leads to 2H‐MoS2 metallic behaviors, improves transition efficiency, and lowers photon energy loss. More importantly, strong light–mass interaction is verified and breaks the energy level degeneracy, makes absorption peaks at 0.6–1.0 eV photon energy region, successfully extends the work region of 2H‐MoS2 to NIR‐II window, greatly improves the optical response and application potential in the photoelectric field. These results not only prove the potential of halogen elements as dopants in bandgap engineering of 2H‐MoS2 but also may indicate a direction for seeking new generation function materials that own excellent performance in the NIR‐II window, which is of great significance to promote the development of optoelectronics and bioimaging applications.

Energy build-up factors estimation for BaZr0.10Ti0.90O3, Ba0.90La0.10TiO3 and Ba0.90La0.10Zr0.10Ti0.90O3 ceramics in shielding applications

The search for materials that serve as good shields for radiation has become very important in light of the increasing exposure to ionizing radiation in various vital sectors. The aim is to search for novel materials with better radiation shielding properties that are stable, nontoxic, and abundant and environment friendly. The solid-state reaction approach has been used to synthesize a few ceramics, including BaZrXTi1-XO3, Ba1-XLaXTiO3 and Ba1-XLaXZrXTi1-XO3 (with x = 0.10) i.eBaZr0.10Ti0.90O3 (BZT), Ba0.90La0.10TiO3 (BLT), and Ba0.90La0.10Zr0.10Ti0.90O3 (BLZT). The density of the prepared samples varies from 6.3471 to 11.6003 g/cm3. The X-ray diffraction technique, shows strong peaks to confirm the crystalline structure of prepared ceramic samples. Using the G-P fitting approach, the advanced radiation shielding parameters (build-up factor) have been evaluated in the photon energy region of 1.5 keV–15 MeV. It is observed from the results that exposure buildup factor (EBF) and energy absorption buildup factor (EABF) are maximum for BLZT and has the minimum value for BZT in the entire photon energy regime. The results of this work should be useful in radiation shielding applications such as in industry, medicine, and nuclear engineering.

Investigation of the nuclear radiation parameters of some Ti alloys for biomedical applications

This study investigates the nuclear radiation parameters of selected Ti alloys with potential biomedical applications. The compatibility with nuclear radiation is essential for these alloys in biomedical applications. To understand the nuclear radiation compatibility for this selected alloy, the gamma rays, neutrons, and charged particle interaction parameters were estimated using EpiXS, NGCal, ESTAR, and SRIM. The gamma rays, neutrons, and charged particle interaction parameters of selected Ti alloys relative to the cortical bone were studied. The Zeff of selected alloys relative to the cortical bone reaches unity in the lower photon energy region. Similar values of energy absorption buildup factor for selected alloys and cortical bone when the gamma energy region lies between 200 keV and 3 MeV. For neutron interaction at incident energy of thermal neutron at 25.4 meV and fast neutron 4 MeV, significant differences exist between selected alloys and cortical bone. From the estimated data, it is observed that among selected alloys, Ti-6Al-4V and Ti-6Al-4V-2.5Cu are comparable with cortical bone in terms of gamma rays and charged particle interactions. The results indicate that Ti-6Al-4V and Ti-6Al-4V-2.5Cu are the most suitable alloys for biomedical applications such as knee, hip, and elbow joints.

Systematic Assessment of Phonon and Optical Characteristics for Gas-Source Molecular Beam Epitaxy-Grown InP1−xSbx/n-InAs Epifilms

Experimental and theoretical assessments of phonon and optical characteristics are methodically accomplished for comprehending the vibrational, structural, and electronic behavior of InP1−xSbx/n-InAs samples grown by Gas-Source Molecular Beam Epitaxy. While the polarization-dependent Raman scattering measurements revealed InP-like doublet covering optical modes (ωLOInP~350 cm−1, ωTOInP~304 cm−1) and phonons activated by disorders and impurities, a single unresolved InSb-like broadband is detected near ~195 cm−1. In InP1−xSbx, although no local vibrational (InSb:P; x → 1) and gap modes (InP:Sb; x → 0) are observed, the Raman line shapes exhibited large separation between the optical phonons of its binary counterparts, showing features similar to the phonon density of states, confirming “two-mode-behavior”. Despite the earlier suggestions of large miscibility gaps in InP1−xSbx epilayers for x between 0.02 and 0.97, our photoluminescence (PL) results of energy gaps insinuated achieving high-quality single-phase epilayers with x ~ 0.3 in the miscibility gap. Complete sets of model dielectric functions (MDFs) are obtained for simulating the optical constants of binary InP, InSb, and ternary InP1−xSbx alloys in the photon energy (0 ≤ E ≤ 6 eV) region. Detailed MDF analyses of refractive indices, extinction coefficients, absorption and reflectance spectra have exhibited results in good agreement with the spectroscopic ellipsometry data. For InP0.67Sb0.33 alloy, our calculated lowest energy bandgap E0 ~ 0.46 eV has validated the existing first-principles calculation and PL data. We feel that our results on Raman scattering, PL measurements, and simulations of optical constants provide valuable information for the vibrational and optical traits of InP1−xSbx/n-InAs epilayers and can be extended to many other technologically important materials.

Uniaxial strain engineering of the electronic and optical properties of phenyl-functionalized black phosphorus

The electronic and optical properties of phenyl-functionalized black phosphorus (phenyl-BP) under uniaxial strain engineering were investigated using first-principles calculations. It revealed that the overall transitions from semiconductor to metallic properties were observed in the phenyl-BP. Notably, when 4% tensile strain was exerted along the armchair direction, phenyl-BP was restored to a p-type semiconductor with a smaller gap of 0.60 eV. Furthermore, compressive strain enhanced its ability to absorb ultraviolet light and high photon energy region around 14 eV. Our results suggested that the strain-induced properties of phenyl-BP provided a theoretical guidance for realizing its full potential in optoelectronic applications.

Detection of hydrated electrons in water-jet immersed in low-pressure plasma by laser-induced desolvation

We detected hydrated electrons in a micrometer-size water jet immersed in a low-pressure plasma by laser-induced desolvation. When we irradiated the 2nd, 3rd, and 4th harmonics of Nd:YAG laser pulses to the water jet, we detected the pulsed current which indicated the transport of electrons from the water jet to the plasma. We observed a proportional relationship between the amplitude of the pulsed current and the laser energy, which is consistent with the conversion from hydrated to free electrons by laser-induced desolvation. The amplitude of the pulsed current increased with the negative bias voltage between the plasma and the water jet. The most remarkable result was found in the relationship between the photon energy and the quantum yield of the electron transport. The experimental quantum yield was orders of magnitude higher than that predicted by a Monte Carlo simulation in a low photon energy region, suggesting the possibility that hydrated electrons we detected in the present experiment have much lower hydration energies than well-known hydrated electrons.

Nonequilibrium quantum transport properties of tetragonal zinc chalcogenide monolayers

Tetragonal zinc chalcogenide monolayers (TZCM) are emerging as interesting electronic materials with a direct band gap and relatively high carrier mobility. In this work, we report a theoretical investigation of electronic transport properties and photoelectric response properties of TZCM with gold contacts by density functional theory (DFT) and non-equilibrium Green's function (NEGF) methods. When there is no gate voltage applied, the current increases nonlinearly as bias voltage increases. Among the four proposed devices, the Au(100)/ZnS/Au(100) device has the best electronic transport performance and is most sensitive to the adjustment of bias voltage and gate voltage. The photocurrent calculation results indicate that the low-frequency oscillatory photocurrent of the Au(100)/ZnSe/Au(100) device in the high photon energy region may have potential applications in ultraviolet light-emitting diodes. The Au(100)/Zn2SeS/Au(100) device has more stable photoelectric response and polarization sensitivity than the Au(100)/Zn2SSe/Au(100) device. The Au(100)/TZCM/Au(100) devices exhibit considerable photocurrent and good extinction ratios. This work could pave the way for the future application of TZCM in the field of optoelectronics and so on.

Determination of Gamma Radiation Shielding Characteristics for Some Iron-Based Metallic Glasses

In this study, the gamma radiation shielding characteristics of metallic glasses having Fe81B13.5Si3.5C2, Fe79B16Si5, Fe78B13Si9 and Fe40Ni38B18Mo4 components and coded as FeBSiC, FeBSi1, FeBSi2 and FeNiBMo were investigated. In order to investigate, the mass attenuation coefficients for metallic glasses in the photon energies range of 0.060 to 2.614 MeV were calculated with the help of WinXCOM program and GEANT4 and FLUKA simulation codes. The linear attenuation coefficient, half and tenth value layers, mean free path, effective atomic number and electron density parameters were calculated with the help of the calculated mass attenuation coefficients. Variations of the calculated gamma radiation shielding parameters with photon energy were discussed. It was observed that mass and linear attenuation coefficients, effective atomic number and electron density parameters decreased with increasing photon energy, while half and tenth value layers and mean free path parameters increased with increasing photon energy. It has been observed that metallic glasses have better gamma shielding capabilities in the low photon energy region, and metallic glass coded as FeNiBMo has better gamma radiation shielding capacity than other studied metallic glasses.

Investigation of gamma radiation shielding characteristics of bismuth reinforced ternary composites in wide photon energy region

The aim of this study is to evaluate gamma ray shielding properties for bismuth doped barite-based ternary polymer composite materials. In the first stage of the study, a polymer matrix was prepared by combining orthophthalic unsaturated polyester resin (OUP), Methyl Ethyl Ketone Peroxide (MEKP) and Cobalt Octoate (6%) (Co-6). Then, barite and bismuth were added in certain proportions as filler material into this polymer matrix and thus ternary composites were produced. Experimental studies for the produced samples were carried out in narrow beam geometry using HPGe detector and 133Ba, 22Na, 137Cs, 60Co radioactive sources which emit photons between 276.4 and 1332.5 keV energy. To determine the gamma ray shielding properties of the produced ternary composites, radiation protection efficiency (RPE), linear attenuation coefficient (μ), mass attenuation coefficient (μ/ρ), half value layer (HVL), tenth value layer (TVL), mean free path (MFP), effective atomic number (Zeff), effective electron density (NE) parameters were obtained. Experimental results were compared with theoretical results obtained with WinXCOM software and GEANT4 Monte Carlo simulation code. Experimental and theoretical results were found to be compatible with each other. According to obtained results, it was found that the sample with the best shielding property among the prepared samples was BaBi50 coded sample.

Investigation of Multi-ionization Processes of Kr and Xe Using Short-pulse X-rays and Time-of-flight Apparatus

The multi-ionization processes of Kr and Xe in the K-edge photon energy region were investigated using short-pulse x-rays and time-of-flight apparatus. The generation of Kr13+ ions in this photon energy region was observed for the first time. The distribution characteristics observed in the experiment, such as the production of Kr13+ ions, high production ratios of Kr4+, Kr5+, and Kr6+ ions, and the existence of a small peak for Kr8+, were quantitatively reproduced by the Monte Carlo simulation for the charge distribution of Kr ions following 1s of inner shell ionization. The highly charged ions were suppressed in the experiments compared with those in the simulation, probably owing to the inhibition of certain Coster-Kronig processes in the highly charged ions, which were not considered for analysis. The charge distribution of Xe ions following 1s of inner shell ionization was also investigated. A similar charge distribution was observed when the photon energy was located between the K and L edges. This is because the Xe 1s hole state mainly undergoes ultrafast relaxation to the 2p hole state owing to the strong dipole transition moment between the 1s and 2p states.

Evaluation of radiation shielding parameters of SiO2-Na2O-K2O-P2O5-BaO glass system

Different glasses i.e. 20 SiO2-7.5 Na2O- 7.5 K2O- (65-x) P2O5- x BaO, have been synthesized using melt quench technique. The glass formation has been confirmed using X-Ray diffraction technique. The advance radiation shielding parameters (Build-up factor) has been evaluating using G-P fitting method. It is observed from results that EBF and EABF are maximum for GBa1 and minimum for GBa4 glass sample in the entire photon energy regime. Results revealed that EBF and EABF varies non-linearly in low photon energy regime due to photoelectric effect absorption role composition dependence. Whereas EBF and EABF, varies nearly linear in the mid and higher photon energy regions due to lower and insignificant compositional dependence respectively. Radiation analysis inferred that GBa4 containing 10 mol.% BaO is the most appropriate among other samples for absorption properties.

Multicomponent Ge-As-Te-Pb chalcogenide glasses for radiations shielding applications

Phy-X/PSD online program is used to obtain various radiation shielding indices in a photon energy region located between 0.15 and 15 MeV for Ge25-As10-Te65-x-Pbx (x = 2, 4, 6, 8, 10 at %) chalcogenide glasses. The linear attenuation coefficient LAC, mass attenuation coefficients MAC, effective atomic number Zeff, effective electron density Neff, half-value layer, HVL, tenth value layer TVL, mean free path MEF, energy absorption and exposure buildup factors (EABF, EBF), and fast neutron cross section FNRCS have been introduced. The findings conclude that the LAC and MAC measurements are greater and therefore better than commercial and traditional glasses. Also, it was found that HVL, TVL, and MFP were reduced with the addition of Pb to the tested glasses, which improve the shielding characteristics. Zeff and Neff of the compositions under study were varied as (42.58- 59.75) and (2.36-3.09 x 1023 electrons/g) respectively. A reduction was noticed in EBF and EABF values with the increment of Pb concentration in the investigated glasses at the entire photon energies, at all values of MFP that emphasize the enhancement of shielding properties of these glasses with the addition of lead. FNRCS were found to be changed between 0.87 and 0.095 Cm-1 as Pb content varies from 0.0 to 0.01 respectively that let these glasses

Study of ruthenium film grown in oxygen environment for x-ray optics application

Ru shows high damage threshold as compared to other standard materials Au, Rh and Pt for high heat load applications in high brilliance synchrotron radiation source and x-ray free electron laser. It is also a promising candidate to be used as a protective capping layer in multilayers for increasing their life time. In the present study, Ru thin films of 500Å thickness were deposited in oxygen environment at different substrate temperatures varying from 70°C to 500°C. In reactive ion beam sputtering process, the flow of Ar and reactive O2 gas was maintained in 4:1 ratio keeping total flow 3 SCCM constant. The deposited films were characterized using grazing incidence x-ray reflectivity (GIXRR), grazing incidence x-ray diffraction (GIXRD) and secondary ion mass spectroscopy (SIMS) techniques. A significant change in GIXRR profile was observed in the sample grown at 100°C and 500°C whereas the GIXRD measurements indicated no significant formation of ruthenium oxide at different temperatures. However, a strong peak of Ru2Si3 (222) at 500°C was observed indicating a strong interfacial reaction at ruthenium/ substrate interface.The experimental data suggested a weak signature of RuO2 phase in the films deposited at RT, 70°C and 100°C and therefore the effect of ruthenium oxide with 10% composition in pure ruthenium was calculated on optical performance in extreme ultra violet region of photon energy (85-115 eV).

Optical transmission, dispersion, and transition behavior of ZnGa2O4transparent ceramic

AbstractAs an emerging transparent ceramic with extremely wide transmission range, the unique optical properties of ZnGa2O4are of particular interest. In this work, ZnGa2O4transparent ceramic with high optical quality was prepared by pressureless sintering and hot isostatic pressing. Its optical behavior was then comprehensively studied. The critical optical data, including refractive index, extinction coefficient, Abbé number, absorption coefficient in infrared region, and phonon frequency, were investigated. The indirect band gap and the phonon energy assisting indirect transition were determined as 4.10 and 0.17 eV, respectively. The modified Sellmeier equation and single‐oscillator dispersion relation were derived to describe the optical dispersion. Benefitting from the weaker tetrahedral Zn–O bond and heavier cationic masses, the infrared transmission range of ZnGa2O4transparent ceramic was broadened significantly. Oxygen vacancies were suggested to induce the absorption in lower photon energy region of ZnGa2O4transparent ceramic, which may enrich its functionalization. This work is meaningful for gaining overall insight into optical properties of transparent materials.

Modeling photocurrent spectra of high-indium-content InGaN disk-in-wire photodiode on silicon substrate

This work reports comprehensive theoretical modeling of photocurrent spectra generated by an In 0.91 Ga 0.09 N/ In 0.4 Ga 0.6 N disk-in-wire photodiode . The strain distribution is calculated by the valence-force-field model, while a realistic band structure of the In x Ga 1 − x N/In y Ga 1 − y N heterostructure is incorporated using an eight-band effective bond-orbital model with spin–orbit coupling neglected. The electrostatic potential is obtained from a self-consistent calculation employing the non-equilibrium Green’s function method. With the strain distribution and band profile determined, a multi-band transfer-matrix method is used to calculate the tunneling coefficients of optically-pumped carriers in the absorbing region. The photocurrent spectra contributed by both single-photon absorption and two-photon absorption (TPA) are calculated. The absorption coefficient is weighted by the carrier tunneling rate and the photon density-of-states (DOS) in the optical cavity formed in the nanowire region to produce the photocurrent. The calculated photocurrent spectra is in good agreement with experimental data, while physical mechanisms for the observed prominent peaks are identified and investigated. We found a dominant influence of the photon DOS near k | | = 0 , causing an enhancement of photocurrent at certain cut-off energies associated with resonance modes in the graded-index waveguide . The main features of photocurrent spectra are determined by the TPA absorption, while the peak positions depend heavily on the polarization of photon. • Modeling of photocurrent spectra in InGaN disk-in-wire with realistic band structure • The photocurrent is predominant by two-photon absorption in low photon energy region • Photocurrent peak positions are affected by resonance modes in waveguide structure

TeO2 for enhancing structural, mechanical, optical, gamma and neutron radiation shielding performance of bismuth borosilicate glasses

The synthesized 12Bi2O3– 8BaO–12ZnO-0.5CeO2-17.5SiO2- (50-x) B2O3- xTeO2 glasses with x = 0, 10, 20, 30 and 40 mol% (coded BiTe-0 to BiTe-40) were investigated in terms of physical, structural, optical and mechanical properties to examine the influence of CeO2 and TeO2 on the heavy metal oxide (HMO) borosilicate network. Density values increased continuously with increasing TeO2 concentration with BiTe-40 glass exhibiting maximum value of 5.0875 gcm−3. This property helped in enhancement of refractive index values from 1.769 for BiTe-0 to 1.942 for BiTe-40. Fourier transform infrared (FTIR) analysis of studied glasses revealed the presence of additional small peak at 683 cm−1 in BiTe-30 and BiTe-40 which confirmed the formation of stable TeO4 units in the glass network. The deep brown colour of the glass existing due to bismuth's presence was nullified by CeO2 and TeO2 additives which improved transparency of the glass. Urbach analysis of these glasses led to optical bandgap variation between 3.27 eV and 2.73 eV for 0–40 mol% TeO2 concentration. Makishima and Mackenzie model was utilized for evaluation of elastic property of the glasses, and Poisson's ratio ranging between 1.935 and 1.953 was obtained. Vickers micro-indentation test on the current glasses revealed decreasing microhardness from 4.116 to 4.076 GPa with TeO2 variation from 0 to 40 mol% at 9.8 N load. Gamma radiation shielding parameters were determined using Phy-X/PSD software and it was found that BiTe-40 glass produce maximum MAC (mass attenuation co-efficient) values in high photon energy region 3.5–15 MeV. The present article also contains a detailed emphasis on behaviour of gamma radiation build-up factors at different incident photon energy and TeO2 concentration. The increasing trend of exposure build up factor (EBF) was seen with increasing penetration depth inside the samples at all energies, indicating that glasses of larger thickness improve the escape probability of photons. Meanwhile, fast neutron removal cross-section (FNRCS) was highest for BiTe-10 sample (0.10118 cm−1) which also surpassed the value of ordinary concrete (0.093 cm−1). Overall, the present glass system bested other conventional shields available commercially in terms of gamma and neutron radiation shielding effectiveness.

Estimation of yield and decay kinetics of intraband luminescence in multiple-parabolic-branch-band model with account of phonons

The emission spectrum of electron intraband luminescence was calculated for a dielectric crystal with conduction band consists of multiple parabolic branches. This shape of this spectrum adequately correspond to the CsI experimental spectra in the photon energy region ≥ 1.2 eV. The calculated total quantum yield of intraband luminescence of CsI is about 78 photons collected by the silicon photomultiplier per 1 MeV of deposited energy of ionizing radiation. This value is about two times higher than the experimental one, the difference is due to the simplification of the model. It was shown that characteristic times of intraband luminescence are about 1 ps.

Croconic Acid Doped Triglycine Sulfate: Crystal Structure, UV-Vis, FTIR, Raman, Photoluminescence Spectroscopy, and Dielectric Properties

Triglycine sulfate (TGS) single crystals doped with croconic acid (CA) were grown by evaporation from aqueous solutions. X-ray diffraction analysis shows a slight reduction in unit cell volume in TGS:CA compared to pure TGS crystals. The polarized Raman and near-infrared absorption spectra show that the positions of most lines resulting from inter- and intramolecular vibrations are in good agreement with those in spectra of undoped TGS crystals. The inclusion of CA in TGS is confirmed by the presence of bands characteristic of CA in the infrared-Fourier transform spectra. The ultraviolet-visible absorption spectra of TGS:CA are characterized by the presence of additional absorption bands (compared to the spectra of pure TGS) located in the transparent region of pure TGS. In the photon energy region 1.6–3.6 eV, a strong “green” luminescence band is present in TGS:CA upon excitation at λ = 325 nm. The position of the emission band depends on the wavelength of the exciting light. Doping of TGS with CA causes pinning of domain walls, which is accompanied by a decrease in amplitude and frequency dispersion of the dielectric anomaly at the phase transition, a decrease in the switchable polarization and an increase in the coercive field of hysteresis loops.

Generation of superintense isolated attosecond pulses from trapped electrons in metal surfaces

Generation of ultrabroadband isolated attosecond pulses (IAPs) is essential for time-resolved applications in chemical and material sciences, as they have the potential to access the spectral water window region of chemical elements, which has yet to be established. Here we propose a numerical scheme for highly efficient high-order harmonic generation and hence the generation of ultrabroadband IAPs in the XUV and soft-x-ray regions. The scheme combines the use of chirped pulses with trapped electrons in copper transition-metal surfaces and takes advantage of the characteristic features of an infrared (IR) single-cycle pulse to achieve high conversion efficiencies and large spectral bandwidths. In particular, we show that ultrabroad IAPs with a duration of 370 as and with a bandwidth covering the photon energy range of 50--250 and 350--450 eV can be produced. We further show that introducing an additional IR single-cycle pulse permits us to enhance the harmonic yield in the soft-x-ray photon energy region by almost seven orders of magnitude. Our findings thus elucidate the relevance of trapped electrons in metal surfaces for developing stable and highly efficient attosecond light sources in compact solid-state devices.