Ultraviolet Domain Research Articles

Exploring the Central Region of NGC 1365 in the Ultraviolet Domain

Active galactic nuclei (AGN) feedback and its impact on their host galaxies are critical to our understanding of galaxy evolution. Here, we present a combined analysis of new high resolution ultraviolet (UV) data from the Ultraviolet Imaging Telescope (UVIT) on AstroSat and archival optical spectroscopic data from the Very Large Telescope/MUSE, for the Seyfert galaxy, NGC 1365. Concentrating on the central 5 kpc region, the UVIT images in the far- and near-UV show bright star-forming knots in the circumnuclear ring as well as a faint central source. After correcting for extinction, we found the star formation rate (SFR) surface density of the circumnuclear 2 kpc ring to be similar to other starbursts, despite the presence of an AGN outflow, as seen in [O iii] 5007 Å. On the other hand, we found fainter UV and thus lower SFR in the direction southeast of the AGN relative to northwest in agreement with observations at other wavelengths from JWST and Atacama Large Millimeter/submillimeter Array. The AGN outflow velocity is found to be lesser than the escape velocity, suggesting that the outflowing gas will rain back into the galaxy. The deep UV data have also revealed diffuse UV emission in the direction of the AGN outflow. By combining [O iii] and UV data, we found the diffuse emission to be of AGN origin.

First-principles calculations to investigate Electronic, Optical, Mechanical, and transport characteristics of novel A2BAuCl6 (A = K/Rb/Cs; B = Sc/Y)

By utilizing FP-LAPW, the structure, electronic, optical, mechanical and Transport characteristic of A2BAuCl6 (A = K/Rb/Cs, B = Sc/Y) were examined by using DFT. The analysis to the band structure plot of the Halide double perovskites (HDP’s) being studied indicated the existence of indirect band-gaps. The compounds A2BAuCl6 (A = K/Rb/Cs, B = Sc/Y) exhibit anisotropic properties, except one compound as seen by their respective shear anisotropy readings of 0.629, 0.532, 1.006, 0.682, 0.803 and 0.977. The materials have inherent ductility, as indicated by their calculated Poisson’s ratios in the range of 0.30 to 0.35. The examined (HDP’s) materials appear to possess indirect band-gaps, as indicated by the band structure plots. The functional inorganic perovskites A2BAuCl6 (A = K/Rb/Cs, B = Sc/Y) haven’t similar band-gap values, as determined using the TB-mBJ (modified Becke Johnson) and TB-mBJ + Soc (Spin orbital coupling) assumptions. The visible and ultraviolet domain have prominent peaks, suggesting potential applications of the compounds in solar cells. Moreover, examination of additional optical characteristics such as reflectivity, conductivity, electron energy loss, and absorption coefficients suggest that it possesses the inherent features of a semiconductor. The maximum figure of merit for all the student compounds is above 0.74. The simulated output forms the foundation for A2BAuCl6 (A = K/Rb/Cs, B = Sc/Y) and are of practical importance for multijunction solar cells.

Investigating the effect of Pb doping on the structural, electronic, magnetic, and optical properties of wurtzite CdS

This study focuses on comprehensively investigating the crystal structure, electronic, magnetic and optical properties of pure and Pb-doped CdS at different concentrations using first-principles methods with the GGA-PBE+U approximation. Our calculations successfully reproduce the experimentally observed optimized lattice parameters and band gap values for both pure and Pb-doped CdS systems. Band structure results show a large and significant reduction in the band gap of Pb-doped CdS at low concentrations, followed by a steady increase at high Pb concentrations. The electron density distribution show the covalent nature between Cd-S and Pb-S. The optical properties of pur and Pb-doped CdS show: a significant increase in absorption and in reflectivity in the visible and ultraviolet domains with doping. Finally, a reduction in optical transmission in the visible energy domain. These optical analyzes provide essential information on the behavior of these materials, thus broadening its practical applications, notably in the design of optoelectronic devices.

Investigation of high-pressure effect on the physical properties of FrNBr3 (N[dbnd]Ca, Sr) non-toxic halide perovskites

Utilizing ab-initio modeling, this study analyzes the possibility of replacing Lead with Francium halide perovskite for use in potential photovoltaic or optoelectronic device applications. Density functional theory is employed to estimate the structural, electronic, bonding, optical, anisotropic elastic, and mechanical characteristics of FrNBr3 (NCa, Sr) at various hydrostatic stresses scaling from 0 to 80 GPa. The calculation of the tolerance factor validates the structural stability. At 0 GPa pressure, the computed lattice constants for FrCaBr3 and FrSrBr3 are 5.78 Å (5.38 Å) and 6.03 Å (5.62 Å), respectively, using GGA (HSE03) approximation potential. FrNBr3 (NCa, Sr) perovskites show increased band gap values using the HSE03 method. Notably, these HSE03-derived values align with the trends observed in the GGA-PBE scheme, under both normal and hydrostatic pressure conditions. As pressure increases, both the lattice constant and unit cell volume decrease significantly. The estimated direct band gaps demonstrate the semiconducting nature of the compounds under ambient pressure. However, when pressure increases, the band gap narrows, increasing conductivity, and makes it as one of the great contenders of microelectronics as well as tandem photovoltaics due to its shift from ultraviolet to visible light energy region. Applying pressure enhances the optical properties, showcasing its utility in various semiconductor applications within the visible ranges and overcoming its limited usage in the ultraviolet domain. In the same vein, the application of hydrostatic pressure significantly impacts mechanical properties without compromising stability. The ductile and anisotropy character become more pronounced when pressure is exerted.

To clump or not to clump

Context. Winds of massive stars have density inhomogeneities (clumping) that may affect the formation of spectral lines in different ways, depending on their formation region. Most of previous and current spectroscopic analyses have been performed in the optical or ultraviolet domain. However, massive stars are often hidden behind dense clouds rendering near-infrared observations necessary. It is thus inevitable to compare the results of such analyses and the effects of clumping in the optical and the near-infrared, where lines share most of the line formation region. Aims. Our objective is to investigate whether a spectroscopic analysis using either optical or infrared observations results in the same stellar parameters with comparable accuracy, and whether clumping affects them in different ways. Methods. We analyzed optical and near-infrared observations of a set of massive O stars with spectral types O4-O9.5 and all luminosity classes. We used Fastwind model atmospheres with and without optically thin clumping. We first studied the differences in the stellar parameters derived from the optical and the infrared using unclumped models. Based on a coarse model grid, different clumping stratifications were tested. A subset of four linear clumping laws was selected to study the differences in the stellar parameters derived from clumped and unclumped models, and from the optical and the infrared wavelength regions. Results. We obtain similar stellar parameters in the optical and the infrared, although with larger uncertainties in the near-infrared, both with and without clumping, albeit with some individual deviating cases. We find that the inclusion of clumping improves the fit to Hα or He II 4686 in the optical for supergiants, as well as that of Brγ in the near-infrared, but it sometimes worsens the fit to He II 2.18 μm. Globally, there are no significant differences when using the clumping laws tested in this work. We also find that the high-lying Br lines in the infrared should be studied in more detail in the future. Conclusions. The infrared can be used for spectroscopic analyses, giving similar parameters as from the optical, though with larger uncertainties. The best fits to different lines are obtained with different (linear) clumping laws, indicating that the wind structure may be more complex than adopted in the present work. No clumping law results in a better global fit, or improves the consistency between optical and infrared stellar parameters. Our work shows that the optical and infrared lines are not sufficient to break the dichotomy between the mass-loss rate and clumping factor.

Classification of Food Additives Using UV Spectroscopy and One-Dimensional Convolutional Neural Network.

Food additives are utilized in countless food products available for sale. They enhance or obtain a specific flavor, extend the storage time, or obtain a desired texture. This paper presents an automatic classification system for five food additives based on their absorbance in the ultraviolet domain. Solutions with different concentrations were created by dissolving a measured additive mass into distilled water. The analyzed samples were either simple (one additive solution) or mixed (two additive solutions). The substances presented absorbance peaks between 190 nm and 360 nm. Each substance presents a certain number of absorbance peaks at specific wavelengths (e.g., acesulfame potassium presents an absorbance peak at 226 nm, whereas the peak associated with potassium sorbate is at 254 nm). Therefore, each additive has a distinctive spectrum that can be used for classification. The sample classification was performed using deep learning techniques. The samples were associated with numerical labels and divided into three datasets (training, validation, and testing). The best classification results were obtained using CNN (convolutional neural network) models. The classification of the 404 spectra with a CNN model with three convolutional layers obtained a mean testing accuracy of 92.38% ± 1.48%, whereas the mean validation accuracy was 93.43% ± 2.01%.

Characterization in the extreme ultraviolet (XUV) domain of microchannel plate based device using synchrotron radiation

Innovative, low-loss, and compact optical systems are essential to meet the experimental requirements of emerging novel radiation sources. The microchannel plate (MCP), a metamaterial-based optical device, shows promising potential for shaping, condensing, and focusing soft x-ray radiation at synchrotron radiation (SR) facilities. This study highlights the impact of MCP optical devices on SR beam condensing capability and their sensitivity to the degree of coherence by investigating the profile of transmitted beams through single and double MCP optical devices. Transmitted diffraction patterns of soft x-ray SR radiation change with energy and radiation modes. At 92 eV, the double MCP-based device affects the beam divergence and degree of coherence more than the single MCP. Moreover, the double MCP device shows potential as a condensing optics at shorter wavelengths, i.e., 480 eV. Experiments were performed at the available end-station of the Circular Polarization beamline at the Elettra synchrotron facility in Trieste, using a high-vacuum chamber with a hexapod system, providing the precise movement necessary to align these diffractive optics. The findings contribute to the development of innovative optical systems for SR and free-electron laser beamlines, paving the way for advanced experiments in spectroscopy, microscopy, and imaging in a wide energy range.

Strain-Induced SiP–PtS2 Heterostructure with Fast Carrier Transport for Boosted Photocatalytic Hydrogen Conversion

Earth-abundant silicon-, phosphorus-, and sulfur-related compounds are crucial for optoelectronic application. Specifically, experimentally proven monolayer SiP has attracted a great deal of attention in above listed field owing to its unique properties but is plagued with challenges such as photocorrosion and poor charge separation. Moreover, theoretical understanding on the relationship of the interface and photocatalytic activity in SiP-based chemicals is not well understood. In this work, hybrid functional first-principles calculations were used to explore the photocatalytic hydrogen evolution activity of SiP–PtS2 heterostructure. Further examination of phonon, ab initio molecular dynamics (AIMD), and elastic property simulations confirms its dynamical stability. Its computed band gap of 1.59 eV is suitable for maximizing solar energy conversion efficiency, with noticeable strong absorption coefficients of 105 cm–1 order across visible–ultraviolet domains, asymmetric decent carrier mobility (∼103 cm2 V–1 s–1), and low exciton binding energy (0.56 eV). Differences in charge density and Bader and Mulliken population analyses reveal that charge flows from the SiP to the PtS2 layers, performing the dual functions of segregating photoinduced charge carriers and increasing their lifetimes. The relative band alignment of the monolayers promotes a spatial separation of the charges. An important feature of this heterostructure is that the band edges cross the water redox potential at pH of 0 upon −2% of compressive biaxial straining, with ΔG for hydrogen evolution reaction (HER) barrier lower than −0.2 eV. The quadratic relationship between biaxial strain and atomic energy indicates that both the system and strains are elastic. Redox thermodynamic analysis predicts facile hydrogen production on the heterostructure. In particular, the calculated maximum solar power conversion efficiency (PCE) and solar-to-hydrogen (STH) efficiency can reach 22.9 and 23.8%, respectively.

Graphene/4H-SiC Schottky photodetector operating in the visible spectrum range

In this work, we present the first experimental results on a Schottky photodetector based on Silicon Carbide (SiC) and Graphene (Gr) designed to operate in the visible spectral range. While SiC has been extensively investigated for various applications in the ultraviolet domain, there are only a few works in the visible range, where SiC exhibits negligible optical absorption. To overcome such intrinsic limit of SiC, we exploit the properties of a single layer of Gr to enhance, significantly, the photodetection performance of the device operating, in our experiments, at the wavelength of λ=633 nm. From the current-voltage (I-V) characteristics, a series resistance of 3.7 kΩ, an ideality factor of 8.4, and the zero-bias Schottky barrier height of 0.755 eV have been calculated. Finally, the internal responsivity, as function of the reverse bias applied to the device, has been measured demonstrating a maximum value exceeding 1 mA/W at -5V.

Ultrafast glimpses of the excitation energy-dependent exciton dynamics and charge carrier mobility in Cs2SnI6 nanocrystals.

Advancements in photovoltaic research suggest that tin-based perovskites are potential alternatives to traditional lead-based structures. Cs2SnI6, specifically, stands out as a notable candidate, exhibiting impressive performance. However, its complete potential remains untapped primarily owing to the limited understanding of its photophysics. In light of this, this study aims to bridge this knowledge gap. To commence our study, we first executed theoretical investigations to locate the energetically diverse excitons within the Brillouin zone. Building on this knowledge, we then utilized transient absorption spectroscopy to investigate their temporal evolution. Herein, we observed the formation of high-energy excitons even when the incident photon energy was below the necessary threshold, which is quite distinctive and intriguing. Of particular interest is the generation of ultraviolet (UV) domain exciton using visible photons, which implies that Cs2SnI6 has the potential for efficient solar light harvesting. Tracking the kinetics revealed that this unique finding arises due to the intertwined formation and decay pathways undertaken by the different excitons, aided by intervalley scattering and phonon absorption processes. In addition, we found that the decay of the UV exciton was unusually slow. Transient mobility investigations were undertaken to probe the carrier transport behavior that further established hot carriers (HCs) in Cs2SnI6 to be highly mobile and susceptible to polaron formation. Overall, our findings demonstrate that Cs2SnI6 is a strong candidate for HC-based photovoltaics because it possesses all the prerequisites desired for such applications.

Effect of Thermal Treatment on the Structure and Morphology of Vanadium Doped ZnO Nanostructures Obtained by Microwave Assisted Sol-Gel Method.

In this paper, we conducted a fundamental study concerning the effect of thermal treatment on the structure and morphology of 2 mol% vanadium doped ZnO nanopowders obtained by microwave assisted sol-gel method (MW). The samples were analyzed by DTA, FTIR, XRD, SEM, and UV-Vis spectroscopy. The DTA results showed that above 500 °C, there was no mass loss in the TG curves, and ZnO crystallization occurred. The XRD patterns of the thermally treated powders at 500 °C and 650 °C showed the crystallization of ZnO (zincite) belonging to the wurtzite-type structure. It was found that in the 650 °C thermally treated powder, aside from ZnO, traces of Zn3(VO4)2 existed. FTIR spectra of the annealed samples confirmed the formation of the ZnO crystalline phase and V-O bands. The micrographs revealed that the temperature influenced the morphology. The increase in the annealing temperature led to the grain growth. The SEM images of the MW powder thermally treated at 650 °C showed two types of grains: hexagonal grains and cylindrical nanorods. UV-Vis spectra showed that the absorption band also increased with the increasing temperature of thermal treatment. The MW sample annealed at 650 °C had the highest absorption in ultraviolet domain.

Boosting the solar conversion efficiency of MoSe2/PtX2 (X = O, S) vdW heterostructure by strain and electric field engineering

Vertically stacking two-dimensional materials via weak van der Waals (vdW) forces is an effective strategy for modulating optoelectronic performance of materials. To accelerate more novel MoSe2-based heterostructure design, the interlayer coupling effect in MoSe2/PtX2 (X = O, S) heterostructure has been systematically studied, from the atomic structure to the electronic and optical properties, on the basis of first-principles calculations and BSE model with scissor inclusion. Density functional theory (DFT) calculations unveil a type-II indirect bandgap measuring between 0.85 and 0.91 eV at HSE06 level, with Bader and charge density difference analyses suggesting occurrence of charge redistributions at the interface and electrons diffusion from MoSe2 to PtX2 layers, driven by large band offsets. The thermodynamic and thermal stabilities of the heterostructures are demonstrated by the negative binding energy and AIMD simulation. The heterostructure interface is influenced by the weak vdW coupling with an equilibrium interlayer distance of 3.01 to 3.08 Å and binding energy of −5.5 to −11.2 meV Å−2, indicating an exothermic process and steady adhesion at the interface. Reasonable lattice mismatch that ranges from 1.5 to 4.7% between the vdW heterostructure and separate monolayers suggests good structure compatibility. The optical performance of the heterostructure was examined using the real and imaginary components of dielectric function, where enhanced light absorption of 104–105 cm−1 and prominent peaks are observed encompassing the infrared to ultraviolet domains. Record high spectroscopic limited maximum efficiency (SLME) of ∼33% was also predicted. The absorption strength of MoSe2/PtO2 and MoSe2/PtS2 enhances with increasing negative external electric field (Eext) and compressive strain, individually, inferring their optical properties modulation by Eext and biaxial strain. Both heterostructures present high carrier mobility up to 1322.98 cm2 V−1 s−1 in zigzag direction.

Highly Efficient Perfect Vortex Beams Generation Based on All-Dielectric Metasurface for Ultraviolet Light.

Featuring shorter wavelengths and high photon energy, ultraviolet (UV) light enables many exciting applications including photolithography, sensing, high-resolution imaging, and optical communication. The conventional methods of UV light manipulation through bulky optical components limit their integration in fast-growing on-chip systems. The advent of metasurfaces promised unprecedented control of electromagnetic waves from microwaves to visible spectrums. However, the availability of suitable and lossless dielectric material for the UV domain hindered the realization of highly efficient UV metasurfaces. Here, a bandgap-engineered silicon nitride (Si3N4) material is used as a best-suited candidate for all-dielectric highly efficient UV metasurfaces. To demonstrate the wavefront manipulation capability of the Si3N4 for the UV spectrum, we design and numerically simulate multiple all-dielectric metasurfaces for the perfect vortex beam generation by combing multiple phase profiles into a single device. For different numerical apertures (), it is concluded that the diffracted light from the metasurfaces with different topological charges results in an annular intensity profile with the same ring radius. It is believed that the presented Si3N4 materials and proposed design methodology for PV beam-generating metasurfaces will be applicable in various integrated optical and nanophotonic applications such as information processing, high-resolution spectroscopy, and on-chip optical communication.

Improvement of optical, dielectric and mechanical properties of a new nanocomposite based on polyvinyl alcohol and layered double hydroxide

In this work, films in the form of poly (vinyl alcohol)/Layered Double Hydroxide (PVA/LDH) nanocomposites were synthesized with different amount of LDH (0%; 4% and 6%), and characterized by X-ray diffraction (XRD), infrared spectroscopy scanning electron microscopy (SEM), impedance spectroscopy and UV-Vis-NIR spectroscopy. Different characterizations were used to investigate the electrical/dielectric, optical and mechanical properties of the nanocomposite films XRD and infrared spectroscopy results showed that clay particles exist in the polymer matrix. Electrical modeling was established using an equivalent electrical circuit consisting of two blocks, and confirmed by fitting the experimental conductivity data according to Jonscher’s double power law. Moreover, the reinforcement of the composite matrix by the addition of LDH particles, showed a shift of the relaxations towards the low frequencies, and led to an increase of dielectric constant, conductivity, and absorption of the light in the ultraviolet domain with a decrease of the gap energy. As for the mechanical properties, namely the Young’s modulus, is tripled when the clay content is about 6%.

Improved stabilization scheme for extreme ultraviolet quantum interference experiments

Interferometric pump–probe experiments in the extreme ultraviolet (XUV) domain are experimentally very challenging due to the high phase stability required between the XUV pulses. Recently, an efficient phase stabilization scheme was introduced for seeded XUV free electron lasers (FELs) combining shot-to-shot phase modulation with lock-in detection Wituschek et al (2020 Nat. Commun. 11 883). This method stabilized the seed laser beampath on the fundamental ultraviolet wavelength to a high degree. Here, we extend this scheme including the stabilization of the XUV beampath, incorporating phase fluctuations from the FEL high gain harmonic generation process. Our analysis reveals a clear signal improvement with the new method compared to the previous stabilization scheme.

First-principles study on electronic and optical properties of single-walled carbon nanotube under an external electric field.

In this study, the electronic and optical properties of one-dimensional (1D) single-walled carbon nanotube (SWCNT) nanostructures, and under the external electric field [Formula: see text] applied in the z-direction, are investigated using density functional theory (DFT) calculations. The applied [Formula: see text] leads to significant modulation of the bandgap and changes the total density of states (TDOS), partial density of states (PDOS), absorption coefficient, dielectric function, optical conductivity, refractive index, and the loss function. The application of the [Formula: see text] on the SWCNT/Carboxyl structure leads to tighten its bandgap. The peaks of TDOS around the Fermi level are very weak. The absorption coefficient increases in visible range and decreases in ultraviolet (UV) domain proportionally with the [Formula: see text]. It is found that electronic structures and optical properties of the SWCNT/Carboxyl could be affected by the [Formula: see text]. All these results provide the important information for understanding and controlling the electronic and optical properties of 1D crystals by the [Formula: see text]. This study establishes a theoretical foundation for our future experimental work regarding optoelectronic properties of the SWCNT/Carboxyl material.

An evaluation of remote sensing algorithms for the estimation of diffuse attenuation coefficients in the ultraviolet bands.

In this study, six algorithms (both empirical and semi-analytical) developed for the estimation of Kd in the ultraviolet (UV) domain (specifically 360, 380, and 400 nm) were evaluated from a dataset of 316 stations covering oligotrophic ocean and coastal waters. In particular, the semi-analytical algorithm (Lee et al. 2013) used remote sensing reflectance in these near-blue UV bands estimated from a recently developed deep learning system as the input. For Kd(380) in a range of 0.018 - 2.34 m-1, it is found that the semi-analytical algorithm has the best performance, where the mean absolute relative difference (MARD) is 0.19, and the coefficient of determination (R2) is 0.94. For the empirical algorithms, the MARD values are 0.23-0.90, with R2 as 0.70-0.92, for this evaluation dataset. For a VIIRS and in situ matchup dataset (N = 62), the MARD of Kd(380) is 0.21 (R2 as 0.94) by the semi-analytical algorithm. These results indicate that a combination of deep learning system and semi-analytical algorithms can provide reliable Kd(UV) for past and present satellite ocean color missions that have no spectral bands in the UV, where global Kd(UV) products are required for comprehensive studies of UV radiation on marine primary productivity and biogeochemical processes in the ocean.

Ab-initio study of structural stability, electronic and optical properties of X2GeSe (X = P and Sb) monolayers

This paper investigated the structural stability, electronic and optical properties of X2GeSe (X = P and Sb) monolayers in a hexagonal structure. The calculations are based on the density functional theory using the plane wave method in the Quantum-Espresso computational package for local density approximation (LDA) and the generalized gradient approximation (GGA). The results of phononic calculations indicate that P2GeSe and Sb2GeSe monolayers are dynamically stable in LDA and GGA approximations. The electronic section of X2GeSe (X = P and Sb) monolayers showed that both compounds are semiconductors. The P2GeSe and Sb2GeSe monolayers in the LDA approximation exhibit a direct bandgap at the Γ point with a quantity of 0.88 and 0.84 eV, respectively. Also, P2GeSe and Sb2GeSe monolayers have an indirect bandgap in the GGA approximation in the Г−K path whit amount of 1.07 and 1.02 eV, respectively. For X2GeSe monolayers (X = P and Sb), the optical gaps calculated from the absorption spectrum confirm the electronic bandgap results. The optical calculations showed that the static dielectric constant ε1(0) decreases in the x and z directions but increases in the y-direction with increasing constant atomic radius from P to Sb atom. According to the results, in both LDA and GGA approximations, the maximum reflections of the P2GeSe monolayer are in the ultraviolet domain of the electromagnetic spectrum and for the Sb2GeSe monolayer, the maximum of reflections occurs in the infrared domain. This result makes the studied monolayers a potential candidate for use in optoelectronic devices as a reflector layer of the electromagnetic beam. The calculated of the energy loss spectrum L(ω) diagram shows that the significant collective excitations of the electron charge density in the crystal, which is considered as the plasmonic peak, are in the y-direction. The values of the static refractive index n0, obtained from the squares of the real part of the dielectric function at zero energy, n0=ε1(0), are very close to that of the refractive index diagram at zero energy. For every examined monolayer, the static refractive index in the y-direction is larger than other x and z directions in both LDA and GGA approximations. Examination of the optical properties of the X2GeSe (X = P and Sb) monolayers in different x, y, and z-directions explains the anisotropy of the studied structures.

Study on quaternary diamond-like Li2CaGeO4 properties for optoelectronic applications

The materials properties of quaternary diamond-like Li2CaGeO4 have been studied. The computations are used through the full-potential linearized augmented plane wave method within the local orbitals and ultra-soft pseudo-potentials. Calculated structural parameters are found to be accordant with those of experiment. The elastic anisotropy of the crystal under focus is visualized and discussed. The calculated elastic constants Cij can permit the determination of the macroscopic mechanical parameters of the material under focus. The low-values of bulk modulus and shear modulus indicate that the material under focus should be a soft material. The higher is the value of the Young's modulus, the stiffer is the material of interest. The material under study is found to be an H→Г indirect band gap semiconductor. The main contributions are due to the Li-p and Li-s orbitals. By increasing the temperature results in a slight decrease of the dielectric constant. The authors findings regarding the electronic and optical spectra reveal that the candidates of interest can be a promising materials in optoelectronic devices for visible and ultraviolet domains.

139 GHz UV phase-locked Raman laser system for thermometry and sideband cooling of 9Be+ ions in a Penning trap

We demonstrate the phase locking of two ultraviolet (UV) laser sources by modulating a fundamental infrared (IR) laser with fourth-order sidebands using an electro-optic modulator and the phase locking of one sideband to a second fundamental IR laser. Subsequent sum frequency generation and second harmonic generation successfully translates the frequency offset to the UV domain. The phase lock at 139 GHz is confirmed through stimulated Raman transitions for the thermometry of 9Be+ ions confined in a cryogenic Penning trap. This technique might be used for the sideband cooling of single 9Be+ ions as well as sympathetic cooling schemes and quantum-logic-based measurements in Penning traps in the future.