Quasi-monochromatic Radiation Research Articles

X-ray imaging of silicon die within fully packaged semiconductor devices

X-ray diffraction imaging (XRDI) (topography) measurements of silicon die warpage within fully packaged commercial quad-flat no-lead devices are described. Using synchrotron radiation, it has been shown that the tilt of the lattice planes in the Analog Devices AD9253 die initially falls, but after 100 °C, it rises again. The twist across the die wafer falls linearly with an increase in temperature. At 200 °C, the tilt varies approximately linearly with position, that is, displacement varies quadratically along the die. The warpage is approximately reversible on cooling, suggesting that it has a simple paraboloidal form prior to encapsulation; the complex tilt and twisting result from the polymer setting process. Feasibility studies are reported, which demonstrate that a divergent beam and quasi-monochromatic radiation from a sealed X-ray tube can be used to perform warpage measurements by XRDI in the laboratory. Existing tools have limitations because of the geometry of the X-ray optics, resulting in applicability only to simple warpage structures. The necessary modifications required for use in situations of complex warpage, for example, in multiple die interconnected packages are specified.

Degradation of Bisphenol A in an Aqueous Solution by a Photo-Fenton-Like Process Using a UV KrCl Excilamp.

Bisphenol A (BPA), a precursor to important plastics, is regarded as a common aquatic micropollutant with endocrine-disrupting activity. In the present study, we explored the capability of a UV KrCl excilamp (222 nm) to degrade BPA by a photo-Fenton-like process using persulfate under flow-through conditions. The first-order rate constants of degradation were obtained and the mineralization of dissolved organic carbon (DOC) was estimated. The results showed complete BPA degradation and high DOC mineralization (70–97%). A comparative analysis of degradation rates and DOC removal in the examined systems (UV, Fe2+/S2O82−, UV/S2O82− and UV/Fe2+/S2O82−) revealed a significant synergistic effect in the photo-Fenton-like system (UV/Fe2+/S2O82−) without the accumulation of toxic intermediates. This indicated that the BPA was oxidized via the conjugated radical chain mechanism, which was based on the photo-induced and catalytic processes involving HO• and SO4−• radicals. The primary intermediates of BPA degradation in the UV/Fe2+/S2O82− system were identified by HPLC/MS and the oxidation pathway was proposed. The high performance of the photo-Fenton-like process employing a quasi-monochromatic UV radiation of a KrCl excilamp offers promising potential for an efficient removal of such micropollutants from aqueous media.

Model of the spectral dependence of changes in the polarization state of laser radiation in magneto-optical crystal in the presence of multiple reflections from its faces

In this work we investigated the phenomena in the Faraday rotator that can affect the polarization state of transmitting laser radiation. We have found that multiple reflections of radiation from the faces of the terbium gallium garnet (TGG) crystal can cause deterioration of radiation extinction ratio and, therefore, isolation properties of Faraday cell. We were able to calculate the impact of this factor on polarization extinction ratio of monochromatic and quasimonochromatic laser radiation transmitting through the crystal.

Photooxidation based on UV/H2O2 process for arsenic removal from aqueous solutions

The main regularities of the photochemical oxidation of arsenic (III) were studied using a mercury-free UV source KrCl excilamp (222 nm). Comparative studies of the effectiveness of direct photolysis and combined oxidation of arsenic (III) in the presence of hydrogen peroxide were performed. It was found that the combined treatment of {UV / H2O2 } achieves a significant intensification of the oxidation process. The considered oxidizing systems according to the oxidation state of As (III) can be ranked according to {UV/H2O2 }>{H2O2 }>{UV}. The ion-radical mechanism of the photochemical oxidation of arsenic in the combined {UV / H2O2} oxidation system using the UV radiation of the KrCl excilamp is proposed. The fundamental possibility of using a mercury-free source of quasi-monochromatic radiation of the KrCl excilamp (222 nm) for the photochemical process based on the combined oxidation system {UV / H2O2} to remove arsenic from aqueous solutions is established.

Algorithm-based spectrometer exploiting colloidal PbS quantum dots

In this work we report on a light analysis system based on narrowband colloidal PbS quantum dot photodetectors. The proposed system is able to identify both the peak wavelength of a quasi-monochromatic radiation and the emission spectrum of an arbitrary light source, in the visible and near infrared spectral range, starting from photocurrent measurements of several photoconductive devices with different spectral responses. We demonstrate the feasibility of our approach, optimizing several system parameters and obtaining a mean error of 5 nm and a maximum resolution of 40 nm as regards the peak wavelength identification and the spectral reconstruction, respectively.

The Quasi-optical Equation in a Medium with Weak Dissipation

The form of a quasi-optical equation for a pulse of quasi-monochromatic radiation propagating in a homogeneous or one-dimensionally inhomogeneous linear medium with dissipation is analyzed. For a layer of an inhomogeneous medium, the effective parameters of an equivalent homogeneous medium are obtained.

X-ray cabinet to deliver highly characterized low-dose soft x-ray radiation to biological samples.

We have designed, built, and tested a climate-controlled, radiation-shielded incubator cabinet for the purpose of analyzing the effects of low-dose x-ray radiation on biological tissues and cell cultures. Bremsstrahlung x rays incident on exchangeable fluorescence plates produce strong, quasi-monochromatic radiation directed toward a small container of biological samples. The x-ray source, sample, and detector are enclosed in an incubator-maintaining the optimal environment for biological samples to increase longevity to a maximum of 72 h. To demonstrate the capabilities of the setup, an example experiment is presented. Rat vascular smooth muscle cell growth was observed after irradiation with characteristic x rays of iron, copper, and calcium to impart doses of 2 mGy each. Cultures show significant spectrum dependent increases in cell number over controls at 48 h after irradiation. The experiment lends credence to the efficacy of the apparatus and shows promise for future low-dose bio-radiation studies.

GAS-PUFF TARGET FOR LASER-PRODUCING PLASMA SXR SOURCE

Mass density spatial distributions of selected gas-puff targets have been determined by radiography, using quasi-monochromatic radiation at a wavelength of 13 nm. Results of spatial distributions of mass densities at various initial reservoir pressures for Nitrogen, Argon and Krypton targets are presented. Changes in the mass density spatial distribution due to a nozzle wear are reported.

Oxidative Degradation of Azo Dyes in Combined Fenton-like Oxidative Systems

Kinetic patterns of the degradation of Methyl Orange (MO) dye are studied upon persulfate (PS) and quasi-monochromatic UV radiation (mercury-free source: KrCl-excilamp, 222 nm, referred to below as UV) treatment in the presence or absence of iron ions. Oxidative systems can be placed in the following order according to the efficiency and rate of dye degradation: {PS/UV/Fe2+} > {PS/UV} > {PS/Fe2+} > UV > PS. It is found that only in the combined {PS/UV/Fe2+} system does the total conversion of MO occur, but its deep mineralization in an aqueous solution is also possible. When this happens, the removal of total organic carbon can be as high as 77%. Inhibitors of radical reactions are used to show that both hydroxyl and sulfate anion radicals participate in oxidative degradation in the combined systems {PS/UV/Fe2+} and {PS/Fe2+}, and the role of sulfate anion radicals is dominant in the process. The possibility of using quasi-monochromatic UV radiation for persulfate activation in the oxidative degradation of azo dyes is shown experimentally.

Optimized x-ray sources for x-ray diffraction measurements at the Omega Laser Facility.

The use of x-ray diffraction (XRD) measurements in laser-driven dynamic compression experiments at high-power laser facilities is becoming increasingly common. Diffraction allows one to probe in situ the transformations occurring at the atomic level at extreme conditions of pressure, temperature, and time scale. In these measurements, the x-ray source is generated by irradiation of a solid foil. Under certain laser drive conditions, quasimonochromatic He-α radiation is generated. Careful analysis of the x-ray source plasma spectra reveals that this radiation is not a single line emission and that monochromaticity is highly dependent on the laser irradiance. In this work, we analyze how the spectra emitted by laser-irradiated copper, germanium, and iron foils at the Omega Laser vary depending on different laser drive conditions and discuss the implications for XRD experiments.

Contrast-enhanced spectral mammography with a compact synchrotron source.

For early breast cancer detection, mammography is nowadays the commonly used standard imaging approach, offering a valuable clinical tool for visualization of suspicious findings like microcalcifications and tumors within the breast. However, due to the superposition of anatomical structures, the sensitivity of mammography screening is limited. Within the last couple of years, the implementation of contrast-enhanced spectral mammography (CESM) based on K-edge subtraction (KES) imaging helped to improve the identification and classification of uncertain findings. In this study, we introduce another approach for CESM based on a two-material decomposition, with which we expect fundamental improvements compared to the clinical procedure. We demonstrate the potential of our proposed method using the quasi-monochromatic radiation of a compact synchrotron source—the Munich Compact Light Source (MuCLS)—and a modified mammographic accreditation phantom. For direct comparison with the clinical CESM approach, we also performed a standard dual-energy KES at the MuCLS, which outperformed the clinical CESM images in terms of contrast-to-noise ratio (CNR) and spatial resolution. However, the dual-energy-based two-material decomposition approach achieved even higher CNR values. Our experimental results with quasi-monochromatic radiation show a significant improvement of the image quality at lower mean glandular dose (MGD) than the clinical CESM. At the same time, our study indicates the great potential for the material-decomposition instead of clinically used KES to improve the quantitative outcome of CESM.

ЭКСИЛАМПЫ КАК ПЕРСПЕКТИВНЫЙ ИСТОЧНИК УФ ИЗЛУЧЕНИЯ ДЛЯ ФОТОХИМИЧЕСКОГО ОБЕЗВРЕЖИВАНИЯ МЫШЬЯКСОДЕРЖАЩИХ ВОД

Актуальность исследования обусловлена необходимостью решения проблемы поступления в водные объекты токсичных веществ, в том числе соединений мышьяка, путем поиска и разработки эффективных фотохимических методов очистки и обезвреживания мышьяксодержащих растворов с использованием экологически чистых окислителей и современных безртутных источников УФ излучения. Цель: изучить возможности использования эксиламп для обезвреживания As-содержащих вод и установить закономерности фотохимической активации окисления мышьяка пероксидом водорода с использованием безртутного источника квазимонохроматического излучения KrCl-эксилампы. Объекты: модельные водные растворы мышьяка (III) с концентрацией 2,7 мкмоль∙л–1 (~0,2 мг/л), приготовленные на дистиллированной (УЭП=2 мкСм/см, рН 5,8) и водопроводной воде. Методы: спектрофотометрическое определение ионов мышьяка (III); контроль рН потенциометрическим методом, съемка электронных спектров поглощения растворов реагирующих веществ; поглощенная мощность излучения эксилампы, определенная методом химической актинометрии с атразином; оценка доз УФ излучения. Результаты. Установлена принципиальная возможность использования безртутного источника квазимонохроматического излучения KrCl-эксилампы (222 нм) для фотохимического окисления As(III) комбинированной системой {УФ/H2O2}. Изучены основные закономерности фотохимического окисления мышьяка (III) с использованием безртутного источника УФ излучения – KrCl-эксилампы (222 нм). Проведены сравнительные исследования эффективности прямого фотолиза и комбинированного окисления мышьяка (III) в водном растворе ультрафиолетовым излучением KrCl-эксилампы в присутствии пероксида водорода. По эффективности окисления As(III) рассмотренные окислительные системы можно выстроить в ряд: {УФ/H2O2}>{H2O2}>{УФ}. При комбинированной обработке {УФ/H2O2} наблюдается существенная интенсификация процесса окисления, через 10 минут остаточная концентрация мышьяка в растворе – ниже ПДК (0,01 мг/л). Также рассмотрено влияние гидрокарбонат-ионов, наиболее характерных анионов природных «водных матриц», на скорость реакции окисления As(III). Предложен ион-радикальный механизм фотохимического окисления мышьяка в комбинированной окислительной системе {УФ/H2O2} с использованием УФ излучения KrCl эксилампы.

Backward collinear acousto-optic diffraction of quasi-monochromatic radiation

This study proposes a theoretical model describing the diffraction of quasi-monochromatic radiation by ultrasound. The mode of backward collinear diffraction is considered in detail. The effects of the spectral width and shape of the contour of the spectral line of laser radiation on the parameters of acousto-optic diffraction are investigated.

Reverse collinear acousto-optic diffraction of quasi-monochromatic radiation

Reverse collinear acousto-optic diffraction of quasi-monochromatic radiation

Peculiarities of electromagnetic field oscillations of a charged particle rotating about a conductive ball

Abstract. The paper investigates some characteristic features of the electromagnetic field of a relativistic charged particle that uniformly rotates about a conductive ball in its equatorial plane. It is assumed that the braking of the particle due to radiation is compensated by an external influence (e.g. the electric force) that compels the particle to turn uniformly in a circle. The magnetic permittivity of the ball is assumed to be one. The work is based on the corresponding exact analytic solutions of Maxwell’s equations. The generalized Drude-Lorentz-Sommerfeld formula for the dielectric function of the conductive ball is used in numerical calculations. It is shown that localized oscillations of a high-amplitude electromagnetic field can be generated at a given harmonic inside the ball at a certain (resonant) particle rotation frequency at a small distance from the surface of the ball. Herewith, at large distances from the trajectory of the particle, these localized oscillations are accompanied by intense radiation at the same harmonic, which is many times more intense than the analogous radiation in the case when the ball is absent. The possibilities of using this phenomenon to develop sources of quasi-monochromatic electromagnetic radiation in the range from giga- to terra hertz frequencies are discussed.

Peculiarities of electromagnetic field oscillations of a charged particle rotating about a conductive ball

Abstract. The paper investigates some characteristic features of the electromagnetic field of a relativistic charged particle that uniformly rotates about a conductive ball in its equatorial plane. It is assumed that the braking of the particle due to radiation is compensated by an external influence (e.g. the electric force) that compels the particle to turn uniformly in a circle. The magnetic permittivity of the ball is assumed to be one. The work is based on the corresponding exact analytic solutions of Maxwell’s equations. The generalized Drude-Lorentz-Sommerfeld formula for the dielectric function of the conductive ball is used in numerical calculations. It is shown that localized oscillations of a high-amplitude electromagnetic field can be generated at a given harmonic inside the ball at a certain (resonant) particle rotation frequency at a small distance from the surface of the ball. Herewith, at large distances from the trajectory of the particle, these localized oscillations are accompanied by intense radiation at the same harmonic, which is many times more intense than the analogous radiation in the case when the ball is absent. The possibilities of using this phenomenon to develop sources of quasi-monochromatic electromagnetic radiation in the range from giga- to terra hertz frequencies are discussed.

Peculiarities in the Formation of X-Ray Fluxes by Waveguide–Resonators of Different Construction

The phenomenon of total external reflection (TER) of quasi-monochromatic X-ray radiation fluxes on a material interface and the effect of waveguide–resonator propagation of these fluxes in nanosize extended slit clearance, as well as a device operating on the basis of this effect—a planar X-ray waveguide–resonator—are briefly described. Experimental data on the formation of an X-ray flux by a composite X-ray waveguide–resonator are presented, and a model describing the decrease in the angular divergence of the formed flux without a decrease in the integral intensity is proposed. The model is based on the conception of partial angular tunneling of the radiation flux in the gap between two consequently mounted and mutually adjusted waveguide–resonators; the tunneling is implemented due to the interaction between interference fields of standing X-ray waves excited by the radiation transported by the slit clearance of these waveguide–resonators.

Application of a Terahertz Multi-Frequency Radiation Source Based on Quantum-Cascade Lasers for Identification of Substances Basing on the Amplitude-Spectral Analysis of the Scattered Field

We demonstrate the possibility of using a multi-frequency terahertz source to identify substances basing on the analysis of relative amplitudes of the terahertz waves scattered by the object. The results of studying experimentally the scattering of quasi-monochromatic radiation generated by a two-frequency terahertz quantum-cascade laser by the surface of the samples containing inclusions of absorbing substances are presented. It is shown that the spectral features of absorption of these substances within the terahertz frequency range manifest themselves in variations of the amplitudes of the waves at frequencies of 3.0 and 3.7 THz, which are scattered by the samples under consideration.

High-Energy, Short-Duration Bursts of Coherent Terahertz Radiation from an Embedded Plasma Dipole

Emission of radiation from electrons undergoing plasma oscillations (POs) at the plasma frequency has attracted interest because of the existence of intriguing and non-trivial coupling mechanism between the electrostatic PO and the emitted electromagnetic wave. While broadband emission from plasma waves in inhomogeneous plasma is well known, the underlying physics of narrowband emission at the plasma frequency observed in experiments and in solar radio-bursts is obscure. Here we show that a spatially-localized plasma dipole oscillation (PDO) can be generated when electrons are trapped in a moving train of potential wells produced by the ponderomotive force of two slightly detuned laser pulses that collide in plasma and give rise to a burst of quasi-monochromatic radiation. The energy radiated in the terahertz spectral region can reach an unprecedented several millijoules, which makes it suitable for applications requiring short pulses of high-intensity, narrowband terahertz radiation.

Characteristic, parametric, and diffracted transition X-ray radiation for observation of accelerated particle beam profile

The applicability of X-ray radiation for the observation of accelerated particle beam profiles is studied. Three types of quasi-monochromatic X-ray radiation excited by the particles in crystals are considered: characteristic X-ray radiation, parametric X-ray radiation, diffracted transition X-ray radiation. Radiation is collected at the right angle to the particle beam direction. It is show that the most intensive differential yield of X-ray radiation from Si crystal can be provided by characteristic radiation at incident electron energies up to tensMeV, by parametric radiation at incident electron energies from tens to hundredsMeV, by diffracted transition X-ray radiation at GeV and multi-GeV electron energies. Therefore these kinds of radiation are proposed for application to beam profile observation in the corresponding energy ranges of incident electrons. Some elements of X-ray optics for observation of the beam profile are discussed. The application of the DTR as a source of powerful tunable monochromatic linearly polarized X-ray beam excited by a multi-GeV electron beam on the crystal surface is proposed.