Photon Energy Research Articles

VACUUM BIREFRINGENCE AND DICHROISM IN A STRONG PLANE-WAVE BACKGROUND

In the present study, we consider the effects of vacuum birefringence and dichroism in strong electromagnetic fields. According to quantum electrodynamics, the vacuum state exhibits different refractive properties depending on the probe photon polarization and one also obtains different probabilities of the photon decay via production of electron-positron pairs. Here we investigate these two phenomena by means of several different approaches to computing the polarization operator. The external field is assumed to be a linearly polarized plane electromagnetic wave of arbitrary amplitude and frequency. Varying the probe-photon energy and the field parameters, we thoroughly examine the validity of the locally-constant field approximation (LCFA) and techniques involving perturbative expansions in terms of the external-field amplitude. Within the latter approach, we develop a numerical method based on a direct evaluation of the weak-field Feynman diagrams, which can be employed for investigating more complex external backgrounds. The polarization operator depends on two parameters: classical nonlinearity parameter ξ and the product η = ωq0/m2 of the laser field frequency ω and the photon energy q0 (m is the electron mass). The domains of validity of the approximate techniques in the ξη plane are explicitly identified.

Ultraviolet Photodissociation of the N,N-Dimethylformamide Cation.

N,N-Dimethylformamide (DMF) provides a useful small-molecule model for studying features of the peptide bond that forms the backbone of proteins. We report results from a comprehensive multimass velocity-map imaging study into the ultraviolet (UV) photolysis of the N,N-dimethylformamide cation (DMF+) at wavelengths of 225, 245, and 280 nm. Electronic structure calculations on DMF and DMF+ were employed to help interpret the experimental results. DMF+ ions are generated by 118 nm single-photon ionization of neutral DMF. Subsequent UV photolysis is found to lead to selective cleavage of the N-CO amide bond. This yields HCO + NC2H6+ as major products, with virtually all of the excess energy released into internal modes of the fragments. The data also indicate a small branching ratio into the HCO+ + NC2H6 product pair, which can be accessed from the 32A' electronic state of DMF+. N-CO bond dissociation can also be accompanied by simultaneous intramolecular hydrogen transfer from the oxygen to the nitrogen end of the amide bond, in which case NCH4+ can be formed efficiently at all three wavelengths. The primary NC2H6+ product is relatively long-lived, but the high degree of internal excitation often results in secondary fragmentation via a variety of pathways to form CH3+, NH4+, NCH2+, and NC2H4+, with secondary dissociation more likely at higher photon energies. The isotropic velocity-map images recorded for the various fragments attest to the long lifetime of NC2H6+ and also imply that dissociation most probably occurs from the same set of electronic states at all wavelengths studied; these are thought to be the 12A' ground state and 22A' first excited state of the DMF+ cation.

Developing an Analysis Procedure and Dispersion Model for Pristine and W-Doped VO2 Thin Films Using Density Functional Theory and Spectroscopic Ellipsometry.

Vanadium dioxide (VO2) and its unique phase transition from semiconductor to metal near room temperature (TIMT = 68 °C) offer significant potential for applications in smart materials and advanced technologies. This transition is accompanied by a drastic modulation of VO2's optical properties in the near- and far-infrared regions. Tungsten (W) has been successfully used as a dopant to lower the transition to room temperature. VO2 is highly dependent on the synthesis method, as for each fabrication protocol, the optical properties differ. Therefore, the optical properties of VO2 must be determined frequently. In this work, a universal analysis procedure to accurately determine the optical properties of all pristine VO2 thin films is presented. Density functional theory is employed to create a dispersion model specifically catered to VO2, a novel approach that justifies the oscillator center energies. This dispersion model explicates the four different contributions to the absorption of VO2 between 2 and 5 eV. We showcase the versatility of our dispersion model by applying it to data sets from the literature, correctly fitting each one. We then further illustrate the robustness of the analysis procedure by successfully applying it to W-doped VO2 thin films. This allows for a direct comparison of the optical properties of pristine and W-doped VO2 well below and well above the transition temperature for the first time. We show that W-doping affects the optical properties almost exclusively in the low-temperature phase for near-infrared photon energies. Indeed, the optical absorption of the doped films is higher than that of the pristine films for photon energies below 1 eV, and the onset of optical absorption is lowered to near 0 eV as opposed to 0.4 eV for pristine VO2.

An optical flow battery enabled by trap-engineered nanophosphors

Flow batteries represent a promising technology for storing electrical energy in circulating electrolyte solutions that contain redox-active chemicals. Inspired by the redox flow battery, in this paper we describe the concept and implementation of an optical flow battery, which stores photon energy in circulating nanophosphor colloids. Similar to the redox flow battery, the optical flow battery enables the conversion between photon energy and chemical energy in a rechargeable manner, facilitating distributed energy storage by decoupling energy and power. We characterized basic cell attributes and performance metrics of this prototype optical flow battery in the context of common assessment methods for conventional redox flow batteries. We envision that this optical flow battery may provide a useful tool for solar energy storage, light delivery in live animals, and light-based therapy, diagnosis, and surgery in medicine.Graphical

Effect of lead oxide addition on gamma radiation shielding properties of newly developed geopolymers: theoretical and simulation studies

The efficiency of geopolymers as an effective immobilization system for various hazardous waste materials can be enhanced by adding PbO to improve its radiation shielding characteristics. In this study, the impact of PbO addition on the shielding properties of geopolymer composites was examined to evaluate the gamma radiation shielding characteristics of the geopolymer using FLUKA and XCOM computer programs. The results showed that adding 10% and 20% lead oxide significantly improved the shielding properties of the investigated geopolymer, mostly at lower photon energies. The higher values of MAC of 59.66728 cm2/g at 0.015 MeV, and 0.03916 cm2/g at 15 MeV for the investigated geopolymers suggest that these materials have improved radiation shielding at lower and intermediate energies due to higher photoelectric absorption and Compton scattering. The findings of this study provided valuable insights for designing high-performance radiation protection in medical imaging facilities, nuclear power plants, industrial radiography and other special radiation installations. Therefore, GEO doped with 20PbO should be deployed to fortify these facilities against ionizing radiations.

Photon-Driven Dye Induction Pyroptosis: An Emerging Anti-Tumor Immunotherapy Paradigm.

Photoimmunotherapy represents a novel and promising modality in anti-tumor immunotherapy, offering new hope in the realm of cancer treatment due to its distinctive mechanism and substantial therapeutic efficacy. This innovative approach synergistically integrates photon technology with immunological principles, utilizing photon energy to activate the body's immune response. Photon-driven pyroptosis, a pivotal element of photoimmunotherapy, has significantly revitalized the advancement of this discipline. To support this critical progress, this minireview offers an exhaustive examination of the organic dyes presently employed for photon-driven pyroptosis, alongside an analysis of the prevailing challenges and opportunities in dye molecule design. It is our aspiration that this minireview will contribute to the acceleration of developments in photon-driven pyroptosis dye and the broader field of photoimmunotherapy.

A low-cost instrumentation for monitoring of the environmental radioactivity

In this work, a low-cost radiation monitoring instrumentation for measuring the environmental gamma radioactivity together with some atmospheric parameters was designed and produced. The device has been built with market available components. The detector section of the device uses a Si-PIN photo-diode as an active element. A tiny current produced from the energy deposition of gamma rays in silicon is amplified in two stages, firstly with a charge sensitive amplifier (CSA) and secondly with a shaping amplifier (SA). The amplified signal is further processed to be converted into digital pulses for counting. The monitor station is designed to be operated remotely in self-sufficient mode, equipped with LoRA module running at 500 MHz to transfer the data remotely to a base station. The base station also includes a LoRA module to receive the data and stores it in an SD card while an OLED display visualizes the recent measurement. Multiple monitor stations can be used to control the radioactivity level in a field simultaneously. This field could be used inside or outside of an interested facility. The noise limit of the detector developed was determined to be as low as 20 keV photon energy. The low-energy detection limit was conservatively set to 40 keV which was still below the 64 keV of the naturally occurring 234Th. Counting the events for hourly, daily or weekly provide statistically significant data depending on the activity of the interested region. All gamma energies above 40 keV from the decays of naturally occurring radioisotopes can be practically observed with this device. The anomalies can be detected using various mathematical algorithms that can be embedded into the microprocessor and the results can be shared with the public.

Holmium ions influence in structural and optical properties of Aluminium Strontium-phosphate glasses for radiation shielding applications

This study details the synthesis of a novel series of Holmium-doped Aluminium Strontium-phosphate glass (HoAlSr- phosphate glass) composed of 55 P2O5 + 5 Al2O3 + 4 MgO + 5 NaF + 10 LiCO3 + 5 CaO + 10 SrCO3 + 5 ZnO + 1 Ho2O3 prepared by melt-quench method and its structural, optical, and physical properties are analysed. Powder −XRD verified its amorphous nature, FTIR shows the existence of large phosphate functional groups, Optical properties such as band gap energy was calculated by acquiring absorption spectra covering the UV, Vis, and NIR ranges. Obtained 3.02 eV optical band gap energy. The refractive index changing with increasing energy. Three peaks in the PL spectra corresponded to Ho3+ transitions: 5I8→ 5G6, 5I8→ 3K8, and 5I8→ 5F3. The glass conducted theoretical studies for radiation shielding properties based on several key parameters. Gamma radiation shielding parameters, including Mean Free path (MFP), Effective atomic number (Zeff), linear attenuation coefficient (LAC), and mass attenuation coefficient (MAC), were obtained with the use of the Phy-X program. MAC data show that when Compton scattering (CS) fluctuates in the intermediate photon energy zone (E > 3 MeV), the area of prominence of CS diminishes. They can cause pair production at higher energies, Compton scattering at intermediate energies, and the photoelectric effect at lower energies. The MFP values of glasses doped with HoAlSr- phosphate glass were shorter, indicating a higher level of shielding efficacy. In this study we are focusing on optical properties changes with presence of Holmium ions and its shielding property using Phy-x software. In this research discovered that the synthetic material has high shielding qualities and can be a valuable shield in environments where X-rays are present. So it will be beneficial at X-ray prompted environment

A DFT-based computational study on a highly and lead-free inorganic new fluoroperovskite of Mg3PF3

Inorganic fluoroperovskite materials are increasingly important in solar technology due to their exceptional structural, optical, electronic, and mechanical properties. This study uses DFT calculations to investigate the properties of Mg3PF3 fluoroperovskite. Our results show a crystal structure and lattice parameter of (a = 4.64 Å) which align with previous theoretical and experimental findings, confirming the accuracy of our calculations. Mechanical analysis reveals that Mg3PF3 is naturally ductile, elastically anisotropic, and stable according to established criteria. The band structure and PDOS indicate that it is a semiconductor with direct bandgap of 3.88 eV at the Γ point, making it suitable for electronic applications. Electron charge density mapping suggests a predominantly ionic bonding nature. Optical property analysis shows significant dielectric constant peaks in the photon energy range favorable for solar cells. Overall, these findings position Mg3PF3 as a promising candidate for solar cell technology, highlighting its potential for enhancing renewable energy solutions.

Study on Pressure-Induced Band Gap Modulation and Physical Properties of Direct Band Gap Ca3NX3 (X = Cl, Br) for Optoelectronic and Thermoelectric Applications

Utilizing density functional theory, we have comprehensively analyzed the structural, electronic, mechanical, transport, and thermodynamic properties of Ca3NCl3 and Ca3NBr3 photovoltaic materials. Furthermore, we investigated the impact of pressures ranging from 0 to 80 GPa and observed that the applied pressure decreases the atomic distances, resulting in significant changes in the physical properties of both materials. We employed GGA-PBE and TB-mBJ functionals to calculate the band structures and density of states, confirming their semiconducting nature. At 0 GPa, both compounds initially display a direct bandgap (Γ-Γ) of 1.5 eV for Ca3NCl3 and 1.26 eV for Ca3NBr3 based on GGA-PBE calculations. In contrast, the TB-mBJ calculations show an increase in the bandgap to 2.25 eV for Ca3NCl3 and 1.84 eV for Ca3NBr3, respectively. When a pressure of 80 GPa was applied, the direct bandgap of Ca3NCl3 and Ca3NBr3 decreased to 0.23 eV and 0.12 eV with GGA-PBE, and to 0.92 eV and 0.74 eV with TB-mBJ, respectively. It was also observed that the effective mass decreases under applied pressure, making these materials promising candidates for solar cell applications. The mechanical stability of both perovskites was maintained up to 80 GPa. Poisson's ratio and Pugh's ratio indicate that both compounds are brittle at 0 GPa but tend to become more ductile under applied stress. The optical properties reveal that pressure alters the dielectric function, absorption spectra, and optical conductivity, causing a red shift from higher to lower photon energies. Several thermodynamic properties, including heat capacity, Debye temperature, thermal expansion coefficient, and entropy, have been calculated, with their dependencies on temperature and pressure illustrated. Finally, the thermoelectric response of these materials is evaluated by examining how various transport parameters - such as the Seebeck coefficient, electrical and thermal conductivity, and power factor - depend on the temperature.

Response of CaSO4:Dy Teflon embedded thermoluminescent dosimeter badge on different ISO phantoms for photons and beta sources using FLUKA and GEANT4

In this study, Monte Carlo codes FLUKA and GEANT4 were used to assess the angular variation in the response of CaSO4:Dy Teflon disc based TLD badge. These badges were positioned on various ISO phantoms to simulate the angular exposures ranging from 0° to 60° for photons within the energy range of 12.3 keV to 1.25 MeV, as well as for 90Sr/90Y and 106Rh/106Ru beta sources. Plots showing the TL response of the discs in terms of Hp(10), Hp(3), and Hp(0.07) as a function of photon energy were obtained for ISO slab, cylindrical, and pillar phantoms, respectively. Additionally, the study estimated the angular variation in the response of disc ratios (R12 and R32) with respect to both photon and beta energies. The simulation results revealed that the response of the open disc (D3) was higher for lower X-ray energies, attributed to an increase in the photoelectric effect. Conversely, the response of the disc under the metal filter (D1) was observed to increase with the angle, indicating the Compton scattering from the cassette body and phantom, especially at lower X-ray energies. Beta response of both disc D2 (under PMMA filter) and D3 found to be decreasing with the angle of incidence while R32 ratio found to be increasing with the angle of incidence for both 90Sr/90Y and 106Rh/106Ru beta sources. Notably, the simulated results demonstrated good agreement with experimental observations, reinforcing the reliability of the Monte Carlo simulations for complex interactions and responses of TLD badges under different irradiation conditions.

Nonlinear LiNbO3 Local Electric Field Enhancement Photonic Crystal with Static Visible and Dynamic Asymmetric Laser Protection.

The rapid development of high-energy laser technology imposes heightened requirements on multifunctional laser protection. In this article, we report a study of static visible and dynamic asymmetric laser protection window, utilizing a one-dimensional photonic crystal comprising LiNbO3 and Nb2O5 defects fabricated by magnetron sputtering technique. The visible light transparency and asymmetric laser protection performance are attributed to photonic crystal energy band properties and significant local electric field enhancement. As 1064 nm laser energy levels are below 14.44 mJ/cm2, the forward and backward incident transmittances are 75.63 and 77.68%, respectively. With an increase in laser energy to 91.62 mJ/cm2, the forward and backward transmittances vary to 7.32 and 71.58% due to the combination of asymmetric electric field enhancement and the third-order nonlinear effect of LiNbO3, achieving dynamic asymmetric laser protection. Notably, the sample exhibits a lower optical protection threshold of 46.08 mJ/cm2 compared to that of traditional optical protection devices. Furthermore, the sample attains an average transmittance of 65.96% within the visible light band. This work presents inspirations for the preparation of multifunctional laser protection optical windows and advanced optical components.

Distribution of the dose response in a silicone-based radio-fluorogenic dosimeter and FWT-60 irradiated with monochromatic low-energy X-rays

In a previous work, we studied the electron spin resonance imaging of the alanine dosimeter irradiated with 0.36–1.8 kGy of 4- and 7-keV monochromatic X-rays and visualized the distribution of alanine radicals as a function of the penetration depth of the X-rays. Herein, the dose-response profile, as a function of the penetration depth, of a silicone-based gel dosimeter and FWT-60 film dosimeter was studied for comparison with the alanine dosimeter. A silicone-based gel dosimeter using dihydrorhodamine 6G (DHR6G) as a fluorescence probe was irradiated with 0–45 Gy of 10-keV monochromatic X-rays. The dose-response profile of the fluorescence was then investigated in detail to demonstrate the properties of low-energy X-ray irradiation. The fluorescence intensity at the surface was less than that inside when irradiated with a higher dose. The total fluorescence intensity per unit dose decreased with the increasing dose. These results were almost the same as those for the alanine dosimeter. At the surface, many of the radicals produced in the silicone elastomer would be lost due to radical-radical recombination before reacting with DHR6G owing to the high linear energy transfer nature of the low-energy X-ray irradiation. The FWT-60 film dosimeter was irradiated with 0.8–10 kGy of 2- and 4-keV monochromatic X-rays. For the FWT-60 film, the dose-response linearly increased with the dose, although its efficiency was far lower than that of the gel dosimeter. Additionally, the slope of the dose-response decreased with the decreasing photon energy. Some of the precursor molecules for the pigment will be directly ionized, transforming into the coloring agent in the FWT-60 film. Finally, the reaction mechanism to produce the pigment in each dosimeter would affect the dose-response properties of irradiation via low-energy X-rays.

Investigation of Gamma Ray Shielding Characteristics of Binary Composites Containing Polyester Resin and Lead Oxide

Ionizing radiation plays an essential role across various fields but also poses significant health risks, requiring effective shielding solutions. This study focuses on the photon shielding properties of PbO-reinforced composites, specifically PbO-0, PbO-2, PbO-4, PbO-6, PbO-8, and PbO-10, through experimental measurements of photon energies ranging from 59.5 keV to 1408.0 keV. The measurements were taken using an HPGe detector. Experimental results were compared to theoretical calculations. Among the tested composites, PbO-10, which contains the highest concentration of lead oxide (PbO), provided the most effective radiation shielding. This sample demonstrated superior mass and linear attenuation coefficients, offering excellent protection at low photon energies. Furthermore, PbO-10 exhibited the lowest half-value layer (HVL) and tenth-value layer (TVL) values, indicating its efficiency in reducing radiation intensity with thinner material layers. It was determined that the experimental TVL results for PbO-O, PbO-2, PbO-4, PbO-6, PbO-8, and PbO-10 at 59.5 keV photon energy were 9.95, 5.98, 4.77, 3.67, 3.22, and 2.71 cm, respectively. With these outstanding attenuation capabilities, PbO-10 is deemed highly suitable for use in medical, industrial, and radiation-heavy environments. In summary, this research emphasizes the effectiveness of PbO-reinforced composites in gamma-ray shielding, with PbO-10 emerging as the top performer, demonstrating great potential for applications that require durable and efficient radiation protection.

3D Lattices of Core/Shell Ge/Mn Quantum Dots in an Alumina Matrix: Structure, Fabrication, and Photo-Electrical Properties

Materials consisting of quantum dots with a semiconductor-core, metal–shell structure often have exciting and tunable photo-electrical properties in a large range of values, and they are adjustable by core and shell structure parameters. Here, we investigated the influence of Mn-shell addition to Ge quantum dots formed in an alumina matrix by magnetron sputtering deposition. We show a well-achieved formation of the 3D regular lattices of Ge-core, Mn-rich shell quantum dots, which were achieved by self-assembled growth mode. Intermixing of Ge and Mn in the shell was observed. The optical, electrical, and photo-conversion properties were strongly affected by the addition of the Mn shell and its thickness. The shell induced changes in the optical gap of the materials and caused an increase in the material’s conductivity. The most significant changes occurred in the photo-electrical properties of the materials. Their quantum efficiency, i.e., the efficiency of the conversion of photon energy to the electrical current, was very strongly enhanced by the shell addition, though it depended on its thickness. The best results were obtained for the thinnest shell added to the Ge core, for which the maximal quantum efficiency was significantly enhanced by more than 100%. The effect was, evidently, the consequence of multiple exciton generation, which was enhanced by the shell addition. The obtained materials offer great potential for various applications in photo-sensitive devices.

Beam quality correction factors for dose measurements around 192Ir brachytherapy sources.

To provide beam quality correction factors ( ) for detectors used in 192Ir brachytherapy dosimetry measurements. Ten detectors were studied, including the PTW 30013 and Exrading12 Farmer large cavity chambers, seven medium (0.1-0.3cm3) and small(<0.1cm3) cavity chambers, and a synthetic microdiamond detector. The kQ,Qo correction factors were calculated at distances from 1 to 10cm away from an 192Ir source, using the EGSnrc Monte Carlo (MC) code. All detectors were calibrated in a 60Co 10×10cm2 reference field provided by standard calibration laboratories. The impact of the central electrode, stem and wall on the detectors' responses in 192Ir photon energies was investigated. An experimental procedure was additionally applied for dose measurements around a microSelectron-v2 192Ir high dose rate (HDR) brachytherapy source using a motorized water phantom. Farmer chambers underestimated the dose near the source due to signal volume averaging effects, resulting in kQ,Qo values ranging from 1.177 and 1.317 at 1cm, decreasing with distance to between 0.980 and 1.005 at 10cm. Small cavity volume detectors should be used close to the source. The kQ,Qo for the studied small and medium cavity volume detectors were found to be close to unity (within 1.3%), showing also a small dependence on source-to-detector distance, except for ion chambers containing high-Z materials in their construction. The presence of high-Z materials caused an overresponse in these detectors, resulting in kQ,Qo values ranging from 0.950 at 1cm to 0.729 at 10cm away from the source. A dose rate constant of (1.114±0.023)cGyh-1U-1 was found in agreement with the literature (within 0.5%). kQ,Qo values were calculated for dose measurements around 192Ir brachytherapy sources. Farmer chambers should be preferred for measurements at increased distances, whereas small or medium cavity volume detectors, not containing high-Z materials, should be used close to the source.

On-shell effective field theory and quantum transport for hard photons

We develop an effective field theory for the description of high energetic or hard photons, the on-shell effective theory (OSEFT). The OSEFT describes the so-called eikonal or semiclassical optical limit, allowing for corrections organized in a systematic expansion on inverse powers of the photon energy. We derive the OSEFT from the Maxwell Lagrangian and study its different properties, such as the gauge symmetry and reparametrization invariance. The theory can be finally formulated in terms of a gauge invariant vector gauge field, without the need to introduce gauge-fixing. We then use the OSEFT to compute corrections to the Wigner photon function and derive its associated side jump effect from reparametrization invariance. Finally, we discuss how to properly define the Stokes parameters from transport theory once quantum effects are considered, so as to preserve their well-defined properties under Lorentz transformations. Published by the American Physical Society 2024

Symmetry Breaking in the Lowest-Lying Excited-State of CCl4: Valence Shell Spectroscopy in the 5.0–10.8 eV Photon Energy Range

We report absolute high-resolution vacuum ultraviolet (VUV) photoabsorption cross-sections of carbon tetrachloride (CCl4) in the photon energy range 5.0–10.8 eV (248–115 nm). The molecular spectrum and electronic structure have been comprehensively investigated together with quantum chemical calculations, providing geometries, bond lengths, vertical excitation energies and oscillator strengths. The major electronic excitations have been assigned to valence and Rydberg transitions which are also accompanied by vibrational excitation assigned to degenerate stretching, v3′t2 and degenerate deformation v4′t2 modes. The rather complex nuclear dynamics along the degenerate deformation mode, v4′t2, have been thoroughly investigated by Time-Dependent Density Functional Theory (TD-DFT) method. The relevant Jahn–Teller distortion operative within the lowest-lying electronic excited-state is shown here for the first time in order to yield a weak absorption feature at 6.156 eV. Further calculations on the potential energy curves for the singlet excited-states along the C–Cl stretching coordinate show the relevance of efficient C–Cl bond excision.

Resonance Raman Scattering of Topological Insulators Bi2Te3 and Bi2 − xSbxTe3 − ySey Thin Films

AbstractPhonon occupation is temperature (T) dependent; it may participate in scattering with electronic states of topological insulators (TIs). Longitudinal optical (LO) phonons and in Bi2 − xSbxTe3 − ySey (BSTS) was resonantly excited by a photon energy (Ep) 2.33 eV due to electronic transition of unoccupied conduction band. The intensity of these modes was enhanced in Bi2Te3 film at Ep 1.87 eV, which is close to the electronic transition of unoccupied Dirac states. Fröhlich coupling strength was the main mechanism for higher intensity of and modes. At 300 K, the intensity of the mode was significantly decayed in both the BSTS and Bi2Te3 at Ep 2.33 and 1.87 eV due to the anharmonic coupling. However, at similar value of T, spectral profile of and modes was not affected because of the lower probability of decay rate of these phonons. In resonant condition, well‐resolved Raman forbidden surface modes were observed at T of 50 K. At 300 K, more asymmetric Fano profile of surface phonon was observed due to the anharmonic coupling. The study indicated that at high T, mode and anharmonic coupling may become primary cause for scattering with electronic states of the TIs. However, at low T, primarily, both the LO phonons participated in the scattering.

Optimization of Soft X-Ray Fresnel Zone Plate Fabrication Through Joint Electron Beam Lithography and Cryo-Etching Techniques

The ability to manufacture complex 3D structures with nanometer-scale resolution, such as Fresnel Zone Plates (FZPs), is crucial to achieve state-of-the-art control in X-ray sources for use in a diverse range of cutting-edge applications. This study demonstrates a novel approach combining Electron Beam Lithography (EBL) and cryoetching to produce silicon-based FZP prototypes as a test bench to assess the strong points and limitations of this fabrication method. Through this method, we obtained FZPs with 100 zones, a diameter of 20 µm, and an outermost zone width of 50 nm, resulting in a high aspect ratio that is suitable for use across a range of photon energies. The process incorporates a chromium mask in the EBL stage, enhancing microstructure precision and mitigating pattern collapse challenges. This minimized issues of under- and over-etching, producing well-defined patterns with a nanometer-scale resolution and low roughness. The refined process thus holds promise for achieving improved optical resolution and efficiency in FZPs, making it viable for the fabrication of high-performance, nanometer-scale devices.