Iodide Lamp Research Articles

Synthesis and characterization of photocatalytic zinc oxide/titanium oxide (core/shell) nanocomposites

In this project, core/shell ZnO/TiO2 nanocomposite samples were prepared using the sol-gel method at different time spans. Characterization of the samples was done using X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM), as well as Raman spectroscopy. The optical properties were evaluated using UV–Vis diffuse reflectance and photoluminescence spectroscopies. The photocatalytic ability of all samples in the degradation of methylene blue (MB) dye by the radiation of Hydrargyrum medium-arc iodide (HMI) lamp was determined. The amount of charge carriers in the samples was calculated using the Mott-Schottky test. The XRD results showed that as the sol-gel preparation time increased, so did the TiO2 shell thickness and its crystallite size. The FE-SEM results revealed the spherical morphology of the samples. The sample prepared in the 15-min time span (ZnTi15) proved as the optimal sample, exhibiting 3 times more photocatalytic activity in comparison to the ZnO control sample. Also, the charge carrier density of the ZnTi15 sample was about 5 times more than that of the ZnO sample. Furthermore, the photoelectrochemical test showed a photocurrent density twice larger for the ZnTi15 sample, which could be attributed to the formation of the heterojunction at the ZnO/TiO2 interface.

High-Intensity Discharge Lamps With High Color Rendering Indices Based on Molecular Radiation of Indium Iodide

This paper deals with mercury-free high-intensity discharges based on indium iodide, that are driven by guided microwaves at 2.45 GHz. The influences of different additives to the lamp on the luminous efficacy as well as on the color rendering index will be shown. Furthermore, the spectral output of pure indium iodide lamps, using argon as auxiliary gas, will be explained by a combination of indium line radiation and molecular emission of the indium iodide molecules. A theoretical model for the molecular emission is shown, which uses the semiclassical description of molecular radiation.

Photobiology and growth of leather coral Sarcophyton cf. glaucum fragments stocked under low light in a recirculated system

Corals are considered promising sources of new natural products and their culture, under controlled conditions, may be the solution for a sustainable and continuous supply of their biomass. Light is of utmost importance for ex situ production of corals harboring zooxanthellae, as their photosynthetic performance can significantly affect coral physiology and growth. The present study aimed to evaluate the effect of three light Photosynthetically Active Radiation (PAR) treatments (50, 80 and 120μmolquantam−2s−1) promoted by 150W (10,000K) Hydrargyrum Quartz Iodide (HQI) lamps on the photobiology, survival and growth of the soft coral Sarcophyton cf. glaucum produced ex situ in recirculated systems. After 60days of experiment coral fragments exposed to 50μmolquantam−2s−1presented significantly higher values of Fv/Fm and Normalized Difference Vegetation Index, zooxanthellae density and most photosynthetic pigment concentrations, when compared with corals under higher PAR values. No significant differences were found on coral fragment survival and growth. S. cf. glaucum production under low PAR intensities can effectively reduce the production costs with electrical power, and simultaneously maximize the production of photosynthetic pigments or bioactive compounds mediated by the zooxanthellae.

Thermodynamic Considerations of Chemical Reaction Phenomena in HID Lamps.

This paper presents considerations on thermodynamic calculations for four lamp phenomena of HID lamps. The first phenomenon is the reactions of Sc or Sc iodide with silica, The standard free energy changes of the reactions associated with Sc2O3 and Sc2Si2O7 formations were calculated. Using these calculation results, the Sc analysis result of the experimental lamp was considered. The second phenomenon is Na reactions with alumina in a high-pressure sodium lamp. The standard free energy changes of the reactions associated with NaAlO2 and β-alumina formations were calculated. The reacting areas for gaseous Na reactions with alumina were defined. The third phenomenon is tungsten transport from the electrodes to the lamp wall in an Fe iodide lamp. By comparing the calculated gaseous Fe pressure with Fe vapor pressure at the electrode temperature region, the formation of the W-Fe alloy which has a low melting point can be explained. The last phenomenon is the chemical reactivity of metal elements with silica. Using the standard free energy formation data for fifty metal oxides, the standard free energy changes of the reactions of fifty metal elements with silica were calculated. From these results fifty metal elements were classified according to the probability of their reaction with silica.

Degradation D'un Herbicide, La Flurochloridone, Par Hydrolyse et Photolyse Hydrolysis and Photodegradation of the Herbicide Flurochloridone

The degradation during hydrolysis and photolysis of flurochloridone, a weed-killer, which belongs to the chemical class of pyrrolidones was studied in diluted solutions. Hydrolysis reactions, carried out on a large pH scale (from 5.5 to 9.5) and for temperatures ranging from 20°C to 40°C, demonstrated that there was no significant elimination of flurochloridone. The decrease of this compound was at the very most 2% or 3% for more than 100 days of hydrolysis. The presence of aquatic humic substances had no effect on chemical stability of this molecule. In neutral or basic medium, hydrolysis led to the epimerisation of the molecule of flurochloridone. Thus, a thermodynamic equilibrium (70 / 30) was obtained between the trans and cis epimerics. No additionnal modification of the structure of this molecule could be observed for long-lasting reactions. UV photolysis (253.7 nm) or polychromatic irradiation (metallic iodide lamp) allowed a total removal of flurochloridone for short reaction times. Some reaction ...

Degradation D'un Herbicide, La Flurochloridone, Par Hydrolyse et Photolyse Hydrolysis and Photodegradation of the Herbicide Flurochloridone

The degradation during hydrolysis and photolysis of flurochloridone, a weed-killer, which belongs to the chemical class of pyrrolidones was studied in diluted solutions. Hydrolysis reactions, carried out on a large pH scale (from 5.5 to 9.5) and for temperatures ranging from 20°C to 40°C, demonstrated that there was no significant elimination of flurochloridone. The decrease of this compound was at the very most 2% or 3% for more than 100 days of hydrolysis. The presence of aquatic humic substances had no effect on chemical stability of this molecule. In neutral or basic medium, hydrolysis led to the epimerisation of the molecule of flurochloridone. Thus, a thermodynamic equilibrium (70 / 30) was obtained between the trans and cis epimerics. No additionnal modification of the structure of this molecule could be observed for long-lasting reactions. UV photolysis (253.7 nm) or polychromatic irradiation (metallic iodide lamp) allowed a total removal of flurochloridone for short reaction times. Some reaction by-products could be eliminated by further UV irradiation, however they remained quite stable with the polychromatic light source. These by-products identified by GC/MS had a chemical structure very close to that of flurochloridone; they were the result of a substitution of a Cl atom and/or of hydroxylation on the five-member cycle.

The application of hydride-generation atomic fluorescence spectrometry in geochemical sample analysis

A double-channel, hydride generation, non-dispersive atomic fluorescence spectrometer has been designed, and its structure and performance are reported in this paper. The spectral interference of bismuth reported in the literature was successfully overcome by using a bromide electrodeless discharge lamp instead of the conventional iodide lamp. The detection limits of arsenic, antimony, bismuth, and mercury in geochemical samples can reach 0.1 ppm, 0.01 ppm, 0.001 ppm and 0.002 ppm, respectively, in geochemical samples. The instrument and its method of application have been widely used with some success in China for geochemical sample analysis. Several examples of its application are reported in this paper.

Invertebrate Productivity in a Subtropical Blackwater River

consistently zero. Raji cells, a lymphoblastoid B cell line, were added to medium after labeling with chromium-51 and incubation in HPD. The cell mixtures were irradiated in polycarbonate tubes on a horizontal platform revolving around a 500 W quartz iodide lamp. Chromium release was assayed immediately after irradiation as a measure of immediate cell lysis. Figure lb shows the chromium release in relation to the p02. There was no chromium release under anaerobic conditions, but this was evident as soon as oxygen was present. A linear relationship existed between pO2 and chromium release until a maximum at a pO2 of 90 mm Hg. Similar findings were shown when cell viability was measured by trypan blue exclusion. Sodium dithionite did not affect the viability of Raji cells and did not change the aggregation status of HPD as measured by polyacrylamide gel chromatography. It was also shown that at low p02, cytotoxicity approaches that seen with high pO2 when the light dose was increased. However, under anaerobic conditions no cytotoxicity occurred even with prolonged irradiation (Figure 2). The results above support the finding that reactive oxygen species are important in the phototoxic process but cannot define the species actually causing cell damage. Further work is being done to investigate the exact nature of these agents.

Determination of chromium in human milk, serum and urine by electrothermal atomic absorption spectrometry without preliminary ashing

In the present study a Perkin-Elmer 5000 atomic absorption spectrometer equipped with a tungsten—iodide lamp for improved background correction at the 357.9 nm chromium absorption line and an HGA 500 graphite furnace were employed for the direct determination of chromium in human serum, milk and urine. The method of standard additions was used: 0.25–0.75 ng Cr was added to 1 ml samples. Except for urine samples, a dilution of 1 + 1 to 1 + 2 with H 2O was necessary in order to obtain correct calibration curves. The average concentration of chromium in all the samples of normal subjects was less than 0.5 ng Cr ml −1. The day-to-day variation for all of the pooled samples was around 10% (relative standard deviation). For urine, the accuracy of the method was tested by comparing the results of another laboratory for the same two round robin samples. Excellent agreement was found between the present method and those of the other laboratory that had used isotope dilution—mass spectrometry and continuum source wavelength modulated echelle—atomic absorption spectrometry to define the chromium concentration in the samples. The detection limit of the method, 0.05 ng Cr ml −1 for urine and serum and 0.1 ng Cr ml −1 for human milk, was sufficient for the biological fluids analyzed. The method was employed for the determination of chromium in 24-h urine samples of maturity onset diabetics supplemented with 20 or 200 μg Cr 3+ d −1 for six weeks. It was shown that the 24-h urinary chromium excretion accurately indicates the daily dietary chromium intake of these patients.

Transport of silica in rare earth iodide arc tubes

In the horizontal operation of dysprosium-thallium and scandium-sodium iodide lamps, the internal surface of the upper portion of the arc tube is etched, causing precipitation on the side and lower portions. This precipitation produces spheroidal outgrowths on the side internal surface and closely bunched fibers on the lower internal surface. These deposits are examined by electron beam microanalysis and micro x-ray diffraction analysis, and are construed to be amorphous SiO2. The transport of silica is found to occur also in a furnace experiment, where dysprosium iodide is heated in an evacuated silica tube held at 750–1150 °C.

Experimental Characterization and Statistical Modeling of Na-Sc Iodide Lamps

The authors have conducted an empirical study of the properties of Na-Sc metal halide lamps over a wide range of compositions and operating conditions. They made lamps with additive compositions which formed grids covering two carefully controlled parameter spaces designed to include most compositions of practical interest. They also used a multivariate linear regression analysis to obtain data fits over regions of parameter space where diffuse, wall-stabilized arcs were obtained; data on constricted arcs were too erratic for this analysis. Their results characterize lamp properties for diffuse arcs and locate the regions in parameter space where constricted arcs are obtained. These results show a number of interdependences that were not previously obvious, and clarify available design trade-offs, as well as providing a diagnostic to insure meeting composition specifications.

Improvement of emission spectra by control of the arc temperature in metal halide lamps.

We have tried to improve the spectral radiant characteristics of the metal halide lamps by controlling the arc temperature by means of an additional metal halide which emits almost no spectral lines in the visible range. This technique has been applied to two kinds of metal halide lamps, the red-colored lithium iodide lamp and the high color rendering thorium iodide lamp. The former has been improved in the purity of red color and the latter has been improved in color rendering property by the addition of aluminum iodide or lead iodide. In both lamps, the arc temperature is lowered, decreasing selectively the visible mercury atomic lines.

Indocyanine green fluorescence angiography.

Indocyanine green (ICG) fluorescence angiography has been further refined for use in both laboratory and clinical investigations. In the present modification of the Zeiss fundus camera all lenses except the aspherical objective lens have been specially antireflection coated to increase light transmission in the spectral region around 800 nm. A 300 watt indium iodide lamp continuous light source has replaced the conventional xenon flash lamp. This light source produces a retinal irradiance of 265 mw, and therefore restricts retinal exposure time to 11.9 seconds, but that time is more than adequate to record passage of dye through the choroid. Spatial resolution of the fundus on the film has been increased from 11.7 microns to 7.4 microns. With these technical refinements the choroidal circulation can be studied at 20 frames per second, which is adequate to document the very rapid movement of blood through the vasculature. ICG angiography may change our interpretations of choroidal circulatory phenomena which are now based on fluorescein angiography, and it clearly is an effective tool in laboratory (experimental) investigations.

Plant Growth Under High Radiant Energy Fluxes

Radiant energy flux density equivalent to peak midday mid-summer sunlight was simulated in an artificially lit controlled environment chamber. High pressure multivapour discharge lamps together with tungsten iodide lamps, installed to give 5·1 kW m−2 of plant growing space, produced a mean photosyntheticallyactive radiant energy flux density of 385 W m−2, 2 m below the thermal barrier, during the course of the experiments. Maize, sorghum, paspalum, ryegrass and soya bean were grown for 28 days from early seedling development at two temperatures (27·5/22·5 °C, 17·5/12·5 °C, day/night) and three irradiance levels simulating one quarter (LL), one-half (ML) and full (HL) peak mid-summer sunlight over 12 h days. Shoot d. wt increased markedly between the LL and ML treatments but only slightly, if at all, between the ML and HL treatments. In comparison with ML treatment plants, those from the HL treatment had shorter main stems, more tillers and fewer, thicker main shoot leaves. Net assimilation rate increased and leaf area ratio decreased with increasing irradiance. As a consequence, relative growth rate did not increase when irradiance exceeded the ML treatment levels. These results suggest that irradiance levels of approximately half-full daylight values are adequate for most routine controlled environment studies where there is little mutual shading between or within plants. Major laboratories must, however, provide high irradiance lighting systems to meet the needs of specialist studies.

The CSI lamp as a source of radiation for solar simulation

The compact source iodide lamp (CSI) provides radiation simulating that of the sun at the earth's surface for testing new products. With a general awareness that solar energy must also be harnessed for the future, a convenient economical system to obtain over 1000 W/m2 is provided by a number of CSI lamps. This type of metal halide lamp operating from the normal supply mains provides useful advantages over other known light sources with its well balanced radiation qualities and its own integral optics providing high utilisation of the available light flux with good directional control and intensity. Increasing use is being made of this lamp for solar simulating testing in a controlled environment where groups of 6-50 lamps or more can meet the technical requirements for solar simulation studies.

Compact iodide lamp from Thorn

Compact iodide lamp from Thorn

An investigation of the effect of impurities on the striking voltage of metal halide lamps

A glow discharge is excited in metal halide lamps, which contain mercury-thallium iodide, mercury-sodium iodide and mercury-sodium-thallium-indium iodide, in order to determine the impurity concentration spectroscopically. A series of band spectra of mercury hydride and a line spectrum of iodine are observed, and the spectral intensities at 4017 A (mercury hydride band) and at 2062 A (iodine line) are measured for this purpose. In mercury-thallium iodide lamps, it was found that hydrogenous impurity present in the arc tube decreases with operating time with a time constant of 60∼150 minutes, which is about the same as the diffusion time of hydrogen through the fused silica tube at the operating temperature. In mercury-sodium iodide lamps, the impurity concentration decreases at first with the same rate as that of the mercury-thallium iodide lamps, and then ceases to decrease gradually after 2 hours operation. Mercury-sodium-thallium-indium iodide lamps show nearly the same behavior as the mercury-sodium iodide lamps. A cross-check is made between the striking voltage and these spectral intensities, and it was found that the impurity concentrations more than 2×10-3 Torr affect the striking voltage of the lamps.

1.2 Measuring technique for partial hydrogen pressures in nitrogen-neon atmospheres

Abstract Gaseous impurities inside the discharge tube of a high pressure metal iodide lamp can have a large influence on the electrical and radiation properties of the lamp. Since the main gaseous impurity is hydrogen this gas must be eliminated from the discharge tube. One way of eliminating this gas is to use a hydrogen gettering material inside the outer bulb of the lamp since, under operational conditions hydrogen can diffuse through the quartz wall of the discharge tube into the outerr bulb. Because most types of high pressure metal iodide lamps have a mixture of a noble gas and nitrogen inside the outer bulb the gettering material must react only with the hydrogen and not with the nitrogen. For this reason the qetter has to be selective. In order to invistigate the selective gettering action of different chemical compounds a simple measuring technique was used to measure continuosly the hydrogen partial pressure inside the nitrogen-noble gas atmosphere. Most investigators use a mass-spectrometer or a gas chromatograph to register the change of the partial hydrogen pressure during the lifetime of the lamp. A much better technique is the use of a nickel diffusion leak combined with a manometer. A higher accuracy can be reached with this methods and it is possible to add or pump away thhe hydrogen without changig the nitrogen or noble gas atmosphere. The selective gettering action of a ZrAl alloys has been examined by this measuring technique and the results of this investigation are given.

Selective gettering of hydrogen in high pressure metal iodide lamps

One of the main problems in the manufacture of high pressure gas discharge lamps is the elimination of gaseous impurities from their arc tubes. Long degassing processes of all the lamp components are necessary in order to produce lamps with a low ignition voltage and good maintenance of the radiation properties. The investigation described in this article deals with a selective getter place in the arc tube which can replace the long degassing process. The getter consists of a piece of yttrium encapsulated in thin tantalum foil. By this way it is possible to use the gettering action of tantalum and yttrium without having reaction between the metal iodide of the arc tube and yttrium. Yttrium is used because this metal can adsorb a large quantity of hydrogen even at a temperature of 1000°C. Hydrogen forms the main gaseous impurity in the high pressure metal iodide lamp. For this reason the adsorption properties like adsorption rate and capacity of the tantalum–yttrium getter for hydrogen are examined, and the results obtained from lamp experiments are given.

The Development and Application of Metal Halide Lamps for Color Filming and Television

The development of high-pressure discharge lamps over the years has been aimed at improving color rendering, efficiency and life. The compact-source iodide (CSI) lamp was initially developed in 400-W and 1,000-W ratings for projector applications, but it was the new demands of outside broadcast color television in 1969 that led to the introduction of this lamp housed in a PAR-64 sealed-beam globe for floodlighting sports stadia from high corner towers. Sports areas with sidelighting were not so well suited to the use of the symmetrical beam CSI floodlights, so another metal halide lamp was introduced — this one with an unjacketed linear arc tube — in 750-W and 1,600-W ratings. For filming, the 1-kW lamp performs exceptionally well as a fill-in source with daylight. At 90 lm/W, it is five to six times more efficient than tungsten-halogen lamps used with blue filters to correct the daylight; four lamps are approximately equivalent to a 225-A brute arc. Control gear is being made simpler and more versatile, and the problem of “beat,” which is already controllable in filming situations, is expected to be overcome completely with techniques now being developed.