Deuterium Lamp Research Articles

Photoluminescence spectra of the Mn2+d-d multiplets transitions of zinc-blende MnTe epitaxial films: laser and deuterium lamp excitation study.

The luminescences of zinc-blende MnTe epitaxial films are respectively excited by a laser and deuterium lamp to study Mn2+d-d multiplets transitions. Besides the inclusion of the band gap, all other excited states related to Mn2+d-d transitions including T14(G4), T24(G4), A14[E4(G4)], T24(D4), E4(D4), and T22(I2) are observed. The shift and broadening of the T14(G4) and T24(G4) lines with increasing temperature are described by the electron-phonon coupling. Step-like energy and intensity shifts for the A14[E4(G4)], T24(D4), E4(D4), and T22(I2) transitions occur in the vicinity of the Néel point, which can be ascribed to the different spin-ordering-induced energy relaxation in ground and excited states of Mn2+d-d multiplets, and these transitions show temperature independence and weak quenching.

Optical properties of SixTiyCzOw composite nanopowder obtained by pulsed plasma chemical method

This paper presents the results of an experimental investigation on the optical properties of the SixTi<yCzOw nanopowders, produced by the pulsed plasma chemical method. Pulsed plasma chemical synthesis is realized on the laboratory stand, including a plasma chemical reactor (6 l) and TEA-500 electron accelerator. The parameters of the electron beam are as follows: 400-450 keV electron energy, 60 ns half-amplitude pulse duration, up to 200 J pulse energy, and 5 cm beam diameter. The spectrum of the diffuse reflection coefficient R(hv) was measured using the AvaSpec-2048-2 (Avantes) spectrometer with the AvaLight-DHS light source (deuterium and halogen-tungsten lamp) and an integrating sphere. The band gap of the obtained composite is 2.03–3.12 eV.

Development of a highly sensitive high-performance thin-layer chromatography method for the screening and simultaneous determination of sofosbuvir, daclatasvir, and ledipasvir in their pure forms and their different pharmaceutical formulations.

The combination of sofosbuvir and daclatasvir or sofosbuvir and ledipasvir is now widely used as an ideal treatment for hepatitis C virus infection. For this purpose, a simple, sensitive, accurate, economic, and precise high-performance thin-layer chromatography was developed and validated for the determination of sofosbuvir, daclatasvir, and ledipasvir in their pure form as well as their different pharmaceutical products. The method used Merck high-performance thin-layer chromatography aluminum plates precoated with silica gel 60 F254 as a stationary phase and mobile phase consisting of methylene chloride/methanol/ethyl acetate/ammonia (25%) (6:1:4:1, v/v/v/v). This system was found to give compact symmetric peaks of sofosbuvir, daclatasvir, and ledipasvir with retardation factors of 0.27 ± 0.01, 0.50 ± 0.007, and 0.68 ± 0.008, respectively. The densitometric scanner was set at 275nm using a deuterium lamp. The calibration curves were linear over the range of 100-3000ng/spot for sofosbuvir, and daclatasvir, and range of 50-3000ng/spot for ledipasvir. The detection limits were 22.5, 31.90, and 15.80 for sofosbuvir, daclatasvir, and ledipasvir. The quantitation limits were 67.50, 95.60, and 47.50 for sofosbuvir, daclatasvir, and ledipasvir. The proposed method was validated according to International Conference on Harmonization (ICH) guidelines and the results were acceptable.

PTB’s radiometric scales for UV and VUV source calibration based on synchrotron radiation

The radiant intensity of synchrotron radiation can be accurately calculated with classical electrodynamics. This primary realization of the spectral radiant intensity has been used by PTB at several electron storage rings which have been optimized to be operated as primary source standards for the calibration of transfer sources in the spectral range of UV and VUV for almost 30 years. The transfer sources are compared to the primary source standard by means of suitable wavelength-dispersive transfer stations.The spectral range covered by deuterium lamps, which represent transfer sources that are easy to handle, is of particular relevance in practice. Here, we report on developments in the realization and preservation of the radiometric scales for spectral radiant intensity and spectral radiance in the wavelength region from 116 nm to 400 nm, based on a set of deuterium reference lamps, over the last few decades. An inside view and recommendations on the operation of the D2 lamps used for the realization of the radiometric scale are presented. The data has been recently compiled to illustrate the chronological behaviour at various wavelengths. Moreover, an overview of the internal and external validation measurements and intercomparisons is given.

Variation in photon flux during extended photochemical aerosol experiments: Implications for atmospheric laboratory simulations

In order to simulate the interaction of sunlight with planetary atmospheres, including Pluto, Titan and the early Earth, many laboratory studies have used high-power broadband lamps with spectral features that extend into the vacuum-ultraviolet (VUV, <200 nm) to initiate photochemistry relevant to the atmosphere of interest. In many cases, experiments are run on the order of hundreds of hours with no accounting for how the photon flux within the system may be evolving with lamp age or a possible buildup of films over optical surfaces when working with high-yield photochemical systems. Given that the nature of photochemistry depends on the ratio of photons to reactants, variations in flux must be taken into account if the system is to be fully understood. In this study, standard N2O actinometry was used to measure the VUV flux of high-intensity deuterium lamps before, during, and after the photochemical synthesis of Titan analog aerosols made from methane or benzene precursors. It was found that VUV photon flux can be decreased by over 50% in under 10 h at higher number densities, with recorded flux losses of over 75% during extended (>60 h) photochemical experiments. While this is only one model system, it is apparent that changes in photon flux during simulations must be taken into account if adequate comparisons of the photochemical kinetics to their respective planetary environments are to be made.

Effects of Taurine on Manganese Accumulations in Gill of the Eastern Oyster, Crassostrea virginica

Taurine (TAU) is an amino acid present in the diet and is a byproduct of cysteine metabolism. TAU is a neuroprotective agent against some neurodegenerative diseases including Alzheimer's, Parkinson's and Huntington's. Manganese (Mn) is a neurotoxin causing Manganism in people which often is confused with Parkinson's disease, an idiopathic neurodegenerative condition causing death of dopamine neurons. Our lab uses the oyster, Crassostrea virginica, as a test model to study toxic effects of metals on animal physiology. C. virginica, has a well‐studied serotonin and dopamine (DA) system controling gill lateral cell (GLC) cilia beating. Our previous work showed Mn disrupts the DA, but not serotonin control of GLC cilia. Our recent work shows TAU protects against the toxic effects of Mn on DA control of GLC cilia. We hypothesize TAU would be beneficial against Mn toxicity in C. virginica by reducing Mn accumulations in gill or by enhancing Mn removal from Mn exposed gill. Gills were treated 2 days in artificial salt water (ASW), ASW with TAU, ASW with Mn, or ASW with TAU and Mn (500 μM each). Gills were rinsed, dried, weighed, and digested in HNO3 in a CEM SP‐D Microwave Digester. Aliquots of digested gill were analyzed for Mn by electrothermal vaporization with deuterium lamp background correction in a Perkin Elmer AAnalyst 800 Atomic Absorption Spectrophotometer with a THGA Graphite Furnace. Results show Mn treatments caused significantly higher Mn accumulations compared to endogenous Mn of ASW controls or TAU (alone) treatment. Samples co‐treated with TAU and Mn had no significant difference in Mn accumulations compared to treatments of Mn alone suggesting TAU does not block Mn accumulation into gill. To determine if TAU could remove Mn from gill, in other experiments gills were treated 2 days with Mn (500 μM), rinsed with ASW, then treated 2 days in either ASW, ASW with TAU, or ASW with EDTA (0.5 to 2.5 mM each). Results showed the highest levels of EDTA (2.5 mM) were the most effective at removing Mn from gill by up to 80% compared to ASW controls. TAU treatments were effective to a lesser degree, removing only about 25% compared to ASW controls. The study shows while TAU did not prevent Mn from accumulating in gill, it did have some beneficial effects in removing Mn, similar to the way chelating agents have long been used in treatment of various pathologies of metal toxicity. Considering TAU is a natural biological component of cells and metabolism and has shown some success as a protective agent in other neurodegenerative diseases, more studies are needed to determine if TAU can be used as an effective, and safer, therapeutic agent in the clinical treatment of Manganism.Support or Funding InformationGrant 2R25GM06003 of the Bridge Program of NIGMS and a Carnegie Foundation award.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Effects of Pre-cooking Process with Acetic Acid and Citric Acid on the Lead (Pb) Concentration in Rice

Rice is one of the most highly consumed food stuff all-around the world. In keeping with this, produced rice of many regions of the world contain high content of the lead (Pb). The present research was done to study the effects of the pre-cooking process of rice with acetic acid and citric acid on the concentration of lead. Rice samples were divided into 5 different pre-cooking treatment groups of soaking in acetic acid 1% and soaking in citric acid 1% (2hrs), boiling with acetic acid 1% and boiling with citric acid 1% (20 min) and finally 6 times rinsing with deionized water. Then, measurement of lead remains was done using the atomic absorption optical spectrometer equipped with detector of graphite furnace with deuterium lamp. The mean concentration of lead in primary rice samples without any processing operation was 87±4.8ppb. The mean concentration of lead in rice samples processed with soaking in acetic acid, soaking in citric acid, boiling with citric acid, boiling in acetic acid and finally 6 times rinsing with deionized water were 55±3.8, 14±1.6, 32±2.4, 14±1.1 and 30±0.5ppb, respectively. The highest reeducation percent of lead in rice samples was obtained in both soaking with citric acid and boiling with citric acid (84%). In keeping with the high concentrations of lead in studied rice samples, obtained concentrations were lower than allowed limit of lead announced with the international standard organization of Iran (150ppb). Boiling and soaking of rice samples with citric acid 1% in home can be a convenient and fast way to reduce the concentration of lead in rice samples.

Optical system contamination: vacuum ultraviolet-modified surfaces

Previous studies have shown that molecular contamination outgassed from nonmetallic materials tends toward deposition on optical surfaces as droplets instead of nearly uniform thin films. Failure to consider the sources and effects of these droplets in an optical instrument omits large throughput losses due to scattering. This paper demonstrates that a simple treatment of optical system surfaces using vacuum ultraviolet (VUV) radiation reduces the formation of molecular contaminant droplets. VUV radiation exposure of a nominally clean silicon surface using a deuterium lamp suffices to remove hydrocarbon and carbonyl species that allow wetting of the surface by the contaminant. The throughput losses of the contamination due to droplet scattering can be reduced significantly.

VUV-absorption cross section of carbon dioxide from 150 to 800 K and applications to warm exoplanetary atmospheres

Context. Most exoplanets detected so far have atmospheric temperatures significantly higher than 300 K. Often close to their star, they receive an intense UV photons flux that triggers important photodissociation processes. The temperature dependency of vacuum ultraviolet (VUV) absorption cross sections are poorly known, leading to an undefined uncertainty in atmospheric models. Similarly, data measured at low temperatures similar to those of the high atmosphere of Mars, Venus, and Titan are often lacking. Aims. Our aim is to quantify the temperature dependency of the VUV absorption cross sections of important molecules in planetary atmospheres. We want to provide high-resolution data at temperatures prevailing in these media, and a simple parameterisation of the absorption in order to simplify its use in photochemical models. This study focuses on carbon dioxide (CO2). Methods. We performed experimental measurements of CO2 absorption cross sections with synchrotron radiation for the wavelength range (115–200 nm). For longer wavelengths (195–230 nm), we used a deuterium lamp and a 1.5 m Jobin-Yvon spectrometer. We used these data in our one-dimensional (1D) thermo-photochemical model in order to study their impact on the predicted atmospheric compositions. Results. The VUV absorption cross section of CO2 increases with the temperature. The absorption we measured at 150 K seems to be close to the absorption of CO2 in the fundamental ground state. The absorption cross section can be separated into two parts: a continuum and a fine structure superimposed on the continuum. The variation in the continuum of absorption can be represented by the sum of three Gaussian functions. Using data at high temperature in thermo-photochemical models significantly modifies the abundance and the photodissociation rates of many species in addition to CO2, such as methane and ammonia. These deviations have an impact on synthetic transmission spectra, leading to variations of up to 5 ppm. Conclusions. We present a full set of high-resolution (Δλ = 0.03 nm) absorption cross sections of CO2 from 115 to 230 nm for temperatures ranging from 150 to 800 K. A parameterisation allows us to calculate the continuum of absorption in this wavelength range. Extrapolation at higher temperature has not been validated experimentally and therefore should be used with caution. Similar studies on other major species are necessary to improve our understanding of planetary atmospheres.

Charging mechanism and application of lunar dust grains

Since the moon has an extremely rarefied atmosphere, the full spectrum of the electromagnetic radiation of the sun reaches the surface, charging the surface dust and affecting its current charge state. Lunar surface dust thus remains electrostatically charged at all times. Charged lunar dust will adversely affect the operations of most mechanical systems required by manned and unmanned exploration missions. Charged dust will also stubbornly adhere to solar panels and thermal radiators, thus reducing their efficiencies. Researches on the charged lunar dust can help to investigate lunar dusty environment as well as to solve those particle-induced problems by both simulation and experiment in laboratory. In this work, two different charging processes of charged lunar dust in the environment of electron beam and the radiation of ultraviolet source are considered. The computer numerical simulation method is used to analyze these two different charging processes of lunar dust, to explore the charging mechanisms of lunar dusts, and to choose an appropriate way of charging for the lunar environment simulation device in laboratory. On the basis of the classic dust charging equation, the charging equation of a dust in pure electron environment is given for the first time in this work. Meanwhile, the charging process under ultraviolet radiation is discussed and combined with the specific application of charging dusts. A solver of fourth-order Runge-Kutta algorithm is made to solve differential equations under two different irradiation sources. The main simulation results show that:1) in electron environment, the surface dust charge number increases as the particle size and the current intensity of electron guns increase, while the charge number increases as the beam spot radius of electron guns decreases; 2) under ultraviolet radiation, the dust charge number increases with the particle size and irradiance increasing, but charging efficiency is slow. A great dust charge number needs a long time radiation from sun (equivalent to 74 deuterium lamps), which means that more ultraviolet radiation sources are essential to speeding up the experiment in laboratory. Although the calculated efficiency of ultraviolet radiation is lower than electron irradiation, the secondary-electron emission, the scattering and the transmission process of electron irradiation are ignored, which can greatly reduce the efficiency of charging by energetic electron guns in the actual experiment. Therefore, comparing these two charging mechanisms and considering the actual design requirements for the space environment simulation device, charging by lots of ultraviolet radiation is an appropriate scheme for electrification of lunar dusts.

Измерение спектральной плотности энергетической освещённости дейтериевых ламп в диапазоне длин волн 200–400 нм с использованием высокотемпературной модели чёрного тела

Измерение спектральной плотности энергетической освещённости дейтериевых ламп в диапазоне длин волн 200–400 нм с использованием высокотемпературной модели чёрного тела

Wavelength-Dependent Damage to Adenoviral Proteins Across the Germicidal UV Spectrum.

Adenovirus, a waterborne pathogen responsible for causing bronchitis, pneumonia, and gastrointestinal infections, is highly resistant to UV disinfection and therefore drives the virus disinfection regulations set by the U.S. Environmental Protection Agency. Polychromatic UV irradiation has been shown to be more effective at inactivating adenovirus and other viruses than traditional monochromatic irradiation emitted at 254 nm; the enhanced efficacy has been attributed to UV-induced damage to viral proteins. This research shows UV-induced damage to adenoviral proteins across the germicidal UV spectrum at wavelength intervals between 200 and 300 nm. A deuterium lamp with bandpass filters and UV light-emitting diodes (UV LEDs) isolated wavelengths in approximate 10 nm intervals. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and image densitometry were used to detect signatures for the hexon, penton, fiber, minor capsid, and core proteins. The greatest loss of protein signature, indicating damage to viral proteins, occurred below 240 nm. Hexon and penton proteins exposed to a dose of 28 mJ/cm2 emitted at 214 nm were approximately 4 times as sensitive and fiber proteins approximately 3 times as sensitive as those exposed to a dose of 50 mJ/cm2 emitted at 254 nm. At 220 nm, a dose of 38 mJ/cm2 reduced the hexon and penton protein quantities to approximately 33% and 31% of the original amounts, respectively. In contrast, a much higher dose of 400 mJ/cm2 emitted at 261 and 278 nm reduced the original protein quantity to between 66-89% and 80-93%, respectively. No significant damage was seen with a dose of 400 mJ/cm2 at 254 nm. This research directly correlates enhanced inactivation at low wavelengths with adenoviral protein damage at those wavelengths, adding fundamental insight into the mechanisms of inactivation of polychromatic germicidal UV irradiation for improving UV water disinfection.

Detection of Vacuum Ultraviolet light by means of SiPM for High Energy Physics experiments

Silicon Photo-Multipliers (SiPMs) are now widely used as light detectors for several high energy physics experiments. The performance of these devices for the detection of scintillation light of liquefied noble gases, such as Liquid Xenon (LXe) or Liquid Argon (LAr), that emit photons in the Vacuum Ultra-Violet region (VUV, λ=100÷200 nm) will be presented. In particular, SiPM arrays produced by Hamamatsu, SensL and AdvanSiD have been tested in terms of quantum efficiency using a VUV measurement system based on a monochromator, a deuterium lamp and a NIST calibrated photodiode. A comparison between standard (plastic window) and completely naked devices has been carried out on the wavelength range of λ=120÷170 nm.Sensitivity in detecting VUV light of tested devices is comparable to standard bialkali PMTs covered with wavelength shifter.

Characterization of light transmissions in various optical fibers with proton beam

As a feasibility study on the development of a fiber-optic radiation sensor for proton therapy dosimetry, we characterized light transmissions of various commercial optical fibers such as silica and plastic based optical fibers by the irradiation of proton beams. In this study, we measured light transmission spectra of optical fibers as a function of absorbed doses of proton beams using a deuterium & tungsten halogen lamps and a spectrometer. To be used as a fiber-optic radiation sensor, the optical fibers should have the radiation resistant characteristics and provide stable output signals during the proton beam irradiation. In this study, we could select suitable optical fibers to be used in the fiber-optic radiation sensor without quenching effects for proton therapy dosimetry. As a result, the light transmittance of the optical fibers had decreasing trends with increasing absorbed dose as expected.

Nonlinear correction of the sensor S11639 in mini-spectrometer

Linear array sensor S11639 is often used in mini-spectrometer for UV measurement. However, when the exposure volume of S11639 is relatively bigger, the non-linearity of the spectral response will appear. This nonlinear effect will affect the dynamic range of the mini-spectrometer, and therefore, nonlinear correction must be carried out. Photoelectric response of S11639 is measured with halogen tungsten lamp and deuterium lamp to find out the linear part between the exposure and the A/D conversion output, and straight line fitting of the data is made to obtain the factors of S11639 in the linear range. Based on it, the theoretical value in nonlinear range is got by extrapolation, and the difference between the theoretical value and the actual measurement value was calculated. The nonlinear correction of S11639 is realized by polynomial fitting with the least square method. At the same time, compared with the experimental results, the error causes of the experimental data are analyzed, and the experiment is provided for better utilization of mini-spectrometer based on S11639 for photoelectric detection in the full dynamic range.

Laboratory investigations of Titan haze formation: In situ measurement of gas and particle composition

Prior to the arrival of the Cassini-Huygens spacecraft, aerosol production in Titan’s atmosphere was believed to begin in the stratosphere where chemical processes are predominantly initiated by far ultraviolet (FUV) radiation. However, measurements taken by the Cassini Ultraviolet Imaging Spectrograph (UVIS) and Cassini Plasma Spectrometer (CAPS) indicate that haze formation initiates in the thermosphere where there is a greater flux of extreme ultraviolet (EUV) photons and energetic particles available to initiate chemical reactions, including the destruction of N2. The discovery of previously unpredicted nitrogen species in measurements of Titan’s atmosphere by the Cassini Ion and Neutral Mass Spectrometer (INMS) indicates that nitrogen participates in the chemistry to a much greater extent than was appreciated before Cassini. The degree of nitrogen incorporation in the haze particles is important for understanding the diversity of molecules that may be present in Titan’s atmosphere and on its surface. We have conducted a series of Titan atmosphere simulation experiments using either spark discharge (Tesla coil) or FUV photons (deuterium lamp) to initiate chemistry in CH4/N2 gas mixtures ranging from 0.01% CH4/99.99% N2 to 10% CH4/90% N2. We obtained in situ real-time measurements using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) to measure the particle composition as a function of particle size and a proton-transfer ion-trap mass spectrometer (PIT-MS) to measure the composition of gas phase products. These two techniques allow us to investigate the effect of energy source and initial CH4 concentration on the degree of nitrogen incorporation in both the gas and solid phase products. The results presented here confirm that FUV photons produce not only solid phase nitrogen bearing products but also gas phase nitrogen species. We find that in both the gas and solid phase, nitrogen is found in nitriles rather than amines and that both the gas phase and solid phase products are composed primarily of molecules with a low degree of aromaticity. The UV experiments reproduce the absolute abundances measured in Titan’s stratosphere for a number of gas phase species including C4H2, C6H6, HCN, CH3CN, HC3N, and C2H5CN.

High-Performance of Al Nanoparticle Enhanced 4H-SiC MSM Photodiodes for Deep Ultraviolet Detection

The size controlled Al nanoparticles (NPs) were prepared by magnetron sputtering and subsequent rapid thermal annealing. Significant deep ultraviolet (DUV) detection enhancement is demonstrated on 4H-SiC metal–semiconductor–metal (MSM) ultraviolet photodiodes (PDs) by introducing the coupling of localized surface plasmon resonance (LSPR) from Al NPs. The peak responsivity of 165 mA/W and quantum efficiency of 93% at 220-nm wavelength are achieved under deuterium lamp illumination when 10-V bias is applied, which is 3.93 times than that without Al NPs. LSPR at wavelength as low as 220 nm is the shortest one ever reported in Al NPs.

Microelements (As, Cd, Pb, Fe, Cu, Zn, Se, Hg) in commercial crustaceans in the Japan Sea

Concentrations of As, Cd, Pb, Hg, Se, Fe, Cu, and Zn in tissues of the commercial crabs and shrimps Chionoecetes opilio, Paralithodes camtschaticus, Pandalus borealis, Pandalus hypsinotus , and Sclerocrangon salebrosa from Primorye waters are determined. The samples were collected by research vessels of Pacific Fish. Res. Center (TINRO) in 2012-2016. Content of metals and arsenic in the soft tissues (from claws and phalanxes of crabs and abdomen of shrimps) was determined by atomic absorption analysis (fiery and flameless methods), using Shimadzu AA-6800 spectrophotometer and mercury analyzer DMA-80 Milestone. As, Cd and Pb concentrations were measured by electrothermal method, with graphite cuvette as an atomizer; Fe, Cu and Zn concentrations were measured in the acetylene/air flame, with single-slot burner as an atomizer and background correction by a deuterium lamp. The standard solutions of the metals were used for calibration. Generally, the microelement composition in soft tissues of all shrimp and crab species is similar. For all species, concentrations of the elements in the soft tissues decrease in the order: Zn &gt; Fe &gt; As &gt; Cu &gt; Se &gt; Cd ~ Pb ~ Hg. All samples are distinguished by heightened concentration of Cu. The following ranges of the toxic metals concentration are observed (mg per kg of wet weight): Pandalus borealis As - 1.6-8.5; Cd - 0.03-0.15; Pb - 0.01-0.02; Pandalus hipsinotus As - 2.78-14.6; Cd - 0.01-0.13; Pb - 0.00-0.01; Sclerocrangon salebrosa As - 5.4-17.3; Cd - 0.01-0.04; Pb - 0.01-0.03; Chionoecetes opilio As - 9.4-14.0; Cd - 0.01-0.05; Pb - 0.01-0.05; Paralithodes camtschaticus As - 3.0-8.8; Cd - 0.0008-0.10; Pb - 0.001-0.009. Cases of exceeding the maximum permissible level of As are detected for all species: in 68.0 % of samples for Paralithodes camtschaticus , in 35.0 % of samples for Sclerocrangon salebrosa , in 33.3 % of samples for Panadalus hipsinotus , in 17.5 % of samples for Panadalis borealis , and in 17.0 % of samples for Chionoecetes opilio .

Cathodoluminescence and Photoluminescence of YPO4:Pr3+, Y2SiO5:Pr3+, YBO3:Pr3+, and YPO4:Bi3+

Herein we describe the synthesis, characterization, and cathodoluminescence of the UV emitting phosphors YPO4:Pr3+, Y2SiO5:Pr3+, YBO3:Pr3+, and YPO4:Bi3+. These photoluminescent UV phosphors exhibited strong luminescence in the UV part of the electromagnetic spectrum when excited by electron bombardment. Spectra have been recorded between 210 and 650 nm at electron beam energies of 5, 10 and 15 keV. The energy efficiencies of YPO4:Pr3+, Y2SiO5:Pr3+, YBO3:Pr3+ and YPO4:Bi3+ in the UV range were 9.2%, 2.7%, 5.1%, and 7.2%, respectively at 15 keV. UV photoluminescence measurements were conducted using 160 nm excitation generated by combining a VUV monochromator with a deuterium lamp.

Metastability of a-SiOx:H thin films for c-Si surface passivation

The adoption of a-SiOx:H films obtained by PECVD in heterojunction solar cells is a key to further increase their efficiency, because of its transparency in the UV with respect to the commonly used a-Si:H. At the same time this layer must guarantee high surface passivation of the c-Si to be suitable in high efficiency solar cell manufacturing. On the other hand the application of amorphous materials like a-Si:H and SiNx on the cell frontside expose them to the mostly energetic part of the sun spectrum, leading to a metastability of their passivation properties. Moreover as for amorphous silicon, thermal annealing procedures are considered as valuable steps to enhance and stabilize thin film properties, when performed at opportune temperature. In this work we explored the reliability of a-SiOx:H thin film layers surface passivation on c-Si substrates under UV exposition, in combination with thermal annealing steps. Both p- and n-type doped c-Si substrates were considered. To understand the effect of UV light soaking we monitored the minority carriers lifetime and SiH and SiO bonding, by FTIR spectra, after different exposure times to light coming from a deuterium lamp, filtered to UV-A region, and focused on the sample to obtain a power density of 50μW/cm2. We found a certain lifetime decrease after UV light soaking in both p- and n-type c-Si passivated wafers according to a a-SiOx:H/c-Si/a-SiOx:H structure. The role of a thermal annealing, which usually enhances the as-deposited SiOx passivation properties, was furthermore considered. In particular we monitored the UV light soaking effect on c-Si wafers after a-SiOx:H coating by PECVD and after a thermal annealing treatment at 300°C for 30min, having selected these conditions on the basis of the study of the effect due to different temperatures and durations. We correlated the lifetime evolution and the metastability effect of thermal annealing to the a-SiOx:H/c-Si interface considering the evolution of hydrogen in the film revealed by FTIR spectra, and we developed a model for the effect of both treatments on the SiH bonding and the metastability shown in the lifetime of a-SiOx:H/c-Si/a-SiOx:H structure. We found that, after UV exposure, thermal annealing steps can be used as a tool for the c-Si passivation recovery and enhancement.