Hydrogen Lamp Research Articles

Matrix isolation study on the 1:1 hydrogen-bonded complexes [H, C, N] … [H, C, N, O

[H, C, N] … [H, C, N, O] complexes were prepared by the photolysis of 1,2,5- and 1,3,4-oxadiazoles, utilizing the cage effect of the low-temperature, rigid Ar matrix. The complexes were characterized and identified by IR spectroscopy aided by quantum chemical computations. In the case of 1,2,5-oxadiazole HCNO⋯HCN, HCN⋯HCNO, HCN⋯HNCO, and HCN⋯HOCN complexes were identified among the 220 nm photolysis products. The 220 nm photolysis of 1,3,4-oxadiazole generated HCN⋯HNCO and HCN⋯HOCN. Upon a secondary photolysis by a Hydrogen lamp, hydrogen isocyanide complexes, namely HCNO⋯HNC, HNCO⋯HNC and HNC⋯HOCN could also be prepared and characterized spectroscopically. On the basis of product distribution, photodecomposition mechanisms are proposed.

A multifunctional setup to record FTIR and UV-vis spectra of organic molecules and their photoproducts in astronomical ices.

This article describes a new, multi-functional, high-vacuum ice setup that allows to record the in situ and real-time spectra of vacuum UV (VUV)-irradiated non-volatile molecules embedded in a low-temperature (10 K) amorphous solid water environment. Three complementary diagnostic tools-UV-visible (UV-vis) and Fourier Transform Infrared (FTIR) spectroscopy and temperature-programmed desorption quadrupole mass spectrometry-can be used to simultaneously study the physical and chemical behavior of the organic molecules in the ice upon VUV irradiation. The setup is equipped with a temperature-controlled sublimation oven that enables the controlled homogeneous deposition of solid species such as amino acids, nucleobases, and polycyclic aromatic hydrocarbons (PAHs) in ice mixtures prepared from precursor gases and/or liquids. The resulting ice is photo-processed with a microwave discharge hydrogen lamp, generating VUV radiation with a spectral energy distribution representative for the interstellar medium. The characteristics, performance, and future potential of the system are discussed by describing three different applications. First, a new method is introduced, which uses broadband interference transmission fringes recorded during ice deposition, to determine the wavelength-dependent refractive index, nλ, of amorphous solid water. This approach is also applicable to other solids, pure and mixed. Second, the UV-vis and FTIR spectroscopy of an VUV-irradiated triphenylene:water ice mixture is discussed, monitoring the ionization efficiency of PAHs in interstellar ice environments. The third and final example investigates the stability of solid glycine upon VUV irradiation by monitoring the formation of dissociation products in real time.

Spectroscopy system using digital camera as two dimensional detectors for undergraduate student laboratory

In this paper, we propose spectroscopy system, which use Complementary metal–oxide–semiconductor (CMOS) image sensor as two dimensional detectors, for studying in undergraduate laboratory. The goal of this system is to make students understand internal structure of commercial spectrometer and characteristic of light spectrum. Light with various wavelengths propagated via variable slit, which is used to adjust width of spectrum, has been focus on reflective grating and then separated to various spectrum. After that, separated spectrum has been recorded by CMOS image sensor which consists of two dimensional array pixels. Each pixel can be determined as wavelength of light by calibrating with Mercury lamp which is standard light source that has exact spectrum value. Measuring factor i.e. sensitivity and spectral resolution have been considered. By using CMOS image sensor, student can observe distribution of real light spectrum and spectrum graph together. The results show that characteristic spectrum of Mercury lamp obtained from our system exact with standard value. By considering measuring factor of spectrometer, small slit width influence system gain high resolution but it cause system has low sensitivity. Spectrum of Mercury lamp, Hydrogen lamp, Argon lamp, led flash of smartphone, and compact fluorescent lamp have been shown and compared. Moreover, our system not only be applied for undergraduate studying, but also might be applied with other optical spectroscopy method in future.

New measurements on water ice photodesorption and product formation under ultraviolet irradiation

The photodesorption of icy grain mantles has been claimed to be responsible for the abundance of gas-phase molecules toward cold regions. Being water a ubiquitous molecule, it is crucial to understand its role in photochemistry and its behavior under an ultraviolet field. We report new measurements on the UV-photodesorption of water ice and its H$_2$, OH, and O$_2$ photoproducts using a calibrated quadrupole mass spectrometer. Solid water was deposited under ultra-high-vacuum conditions and then UV-irradiated at various temperatures starting from 8 K with a microwave discharged hydrogen lamp. Deuterated water was used for confirmation of the results. We found a photodesorption yield of 1.3 $\times$ 10$^{-3}$ molecules per incident photon for water, and 0.7 $\times$ 10$^{-3}$ molecules per incident photon for deuterated water at the lowest irradiation temperature, 8 K. The photodesorption yield per absorbed photon is given and comparison with astrophysical scenarios, where water ice photodesorption could account for the presence of gas-phase water toward cold regions in the absence of a thermal desorption process is addressed.

Remediation of a synthetic textile wastewater from polyester-cotton dyeing combining biological and photochemical oxidation processes

Abstract This study reports an integrated treatment strategy for synthetic polyester-cotton dyeing wastewater, combining biological and photochemical oxidation processes. The biodegradability of all constituents, dyes and dyeing auxiliary products, present in the synthetic polyester dyeing textile wastewater were firstly analysed through a Zahn-Wellens test. More than 80% of the constituents are easily biodegradable, being possible to achieve its complete removal by biological oxidation. Consequently, the synthetic wastewater was firstly subject to a biological oxidation, achieving a dissolved organic carbon (DOC) removal of 76%, resulting in a bio-treated wastewater with 84 mg L −1 of DOC. The colour reduction was less than 5% Platinum-Cobalt Scale (Pt-Co scale), 9% (DFZ 436nm ), 3% (DFZ 525nm ) and 0% (DFZ 620nm ), (DFZ - DurchsichtFarbZahl , visual colour number in German). Thus, UVC/H 2 O 2 and photo-Fenton (PF) oxidation processes were used as a polishing step for the decolourisation of bio-treated textile wastewater. The PF reaction did not promote wastewater decolourisation as shown by the colour indicators monitored. Moreover, the addition of oxalic acid did not result in an enhancement of the PF reaction. On the other hand, the photolysis of hydrogen peroxide using UVC radiation showed decolourisation efficiencies of 71% (Pt-Co method), 86% (DFZ 436nm ) and 97% (DFZ 525nm ) and more than 40% of mineralisation, consuming 14.1 mM H 2 O 2 and 3.1 kJ UVC L −1 of energy dosage (time = 95 min; 6 W UVC lamp; natural pH = 8.4; T = 30 °C). The effect of hydrogen peroxide dosage, lamp power, solution pH and temperature on the UVC/H 2 O 2 efficiency for wastewater decolourization was evaluated. During the photochemical reaction some low-molecular-weight carboxylic acids were detected, as oxalic acid, maleic acid and tartaric acid. The integrated treatment strategy was able to achieve a wastewater quality in agreement with the discharge limits imposed by legislation, and the total operating costs was 2.33 € m −3 .

Photostability of amino acids to Lyman α radiation: Glycine

The amino acids already detected in Solar System bodies and researched in Interstellar Medium are of particular importance for the chemistry related to the origin of life since they are constituents of all living organisms. Several amino acids have been identified in meteorites carbonaceous with significant concentration, while the existence of glycine in regions of star formation has been claimed. To interpret the viability of amino acids in pre-biotic astrochemistry is important to investigate the stability of these compounds in extraterrestrial surroundings. This study investigates, in the laboratory, the stability of glycine to the action of ultraviolet radiation, in spectral region around the wavelength of the Lyman α line (1216Å) produced by a hydrogen lamp. 252Cf-PDMS of positive and negative desorbed ions was performed for glycine, before and during the irradiation, and the dependence of the ion desorption yields on the irradiation time is determined. As a result, the relative photostability curves of the molecular and dimer ions are observed to be a single exponential decay with a time constant 376min for positive desorbed ions and 675min for negative ones. The photodissociation cross section found for glycine molecule at room temperature, when positive secondary ions are considered, is 17Mb; this value drops to 9Mb when negative secondary ions are analyzed. This new methodology offers a complementary way of understanding the photonic interaction in amino acids, allowing discussion on polymerization and/or radiation induced phase transition effects.

Technical Note: VUV photodesorption rates from water ice in the 120–150 K temperature range – significance for Noctilucent Clouds

Abstract. Laboratory studies have been carried out with the aim to improve our understanding of physicochemical processes which take place at the water ice/air interface initiated by solar irradiation with a wavelength of 121.6 nm. It was intended to mimic the processes of ice particles characteristic of Noctilucent Clouds (NLCs). The experimental set-up used includes a high-vacuum chamber, a gas handling system, a cryostat with temperature controller, an FTIR spectrometer, a vacuum ultraviolet hydrogen lamp, and a microwave generator. We report the first results of measurements of the absolute photodesorption rate (loss of substance due to the escape of photoproducts into gas phase) from thin (20–100 nm) water ice samples kept in the temperature range of 120–150 K. The obtained results show that a flow of photoproducts into the gas phase is considerably lower than presumed in the recent study by Murray and Plane (2005). The experiments indicate that almost all photoproducts remain in the solid phase, and the principal chemical reaction between them is the recombination reaction H + OH → H2O which is evidently very fast. This means that direct photolysis of mesospheric ice particles seems to have no significant impact on the gas phase chemistry of the upper mesosphere.

Luminescence of hafnium dioxide films produced from hafnium dipivaloylmethanate

A technique is developed for measuring luminescence spectra of hafnium dioxide using a hydrogen lamp as an excitation source. The luminescence spectra of the as-grown and annealed hafnium dioxide films prepared by chemical deposition from volatile hafnium dipivaloylmethanate on the Si(111) substrates are measured at room temperature. Intense luminescence at λ ≌ 280 nm is characteristic of nanocrystallites of monoclinic modification. The band gap width is found to be ≌ 5.76 eV. It is shown that the film composition significantly deviates from the stoichiometric one.

Photo-enhanced chemical vapour deposition of hydrogenated amorphous silicon carbon using an internal discharge lamp

Hydrogenated amorphous silicon carbon (a-Si 1− x C x :H) is becoming an increasingly important technological materials with a wide and controllable bandgap. Using an internal hydrogen lamp, a-Si 1− x C x :H was produced from a mixture of monosilane and methane or acetylene. Raman and TEM measurements showed that these films are highly amorphous with occasional small microcrystals. When using acetylene as the gaseous source of carbon, the refractive index decreases from 3.8 to 2.2 and the bandgap increases from 1.7 to 2.4 eV as the gas ratio ( C 2 H 2 SiH 4 increases from 0.25 to 2.7. When using methane, a CH 4 SiH 4 gas ratio of the order of 10 is necessary to produce a film with a refractive index of 3.0 and the increase in the optical bandgap is limited to 0.3 eV. The photoluminescence peak energy corresponds well to the optical bandgap and the difference between the peak energy and the bandgap remains within 0.3 eV at most. The reaction mechanism of the deposition is discussed.

High intensity hydrogen lamp employing helicon wave plasma and its application to Si and SiO 2 etching

A high intensity hydrogen Lyman α, H α (10.2 eV) employing helicon wave plasma has been studied as a VUV light source and applied to Si and SiO 2 etching. NF 3 was highly dissociated by H α irradiation at higher pressure, while the Si etch rate dropped rapidly with distance from the window due to recombination loss of fluorine atoms. An anisotropic etching of n + poly-Si under VUV irradiation was achieved. This may be performed by dominant photo-etching of altered layers generated as a result of reaction of Cl atoms with phosphorus atoms. However, details are not understood well.

Primary reaction processes in the deposition of diamond-like carbon films by photon-enhanced CVD of methane using a windowless hydrogen lamp

Thin films of diamond-like carbon have been deposited using a photon-enhanced CVD method. Initial results have been reported previously. This paper investigates the possible mechanisms involved in film growth by electrical characterization of the plasma in the chamber, and by relating the variation in film growth rate to deposition pressure. The results indicate that the primary deposition mechanism is due to phyotolysis, with CVD due to diffusion of the hydrogen plasma from the lamp playing a lesser role. Material properties of the films have been studied by many methods, including Raman spectroscopy and elastic recoil detection analysis. These results are reported here and, in agreement with previous work, indicate that the films produced are semiconducting hydrogenated amorphous carbon, with hydrogen concentrations of between 35 and 45 at.%.

Deposition of diamond-like carbon films by photon-enhanced chemical vapour deposition of methane using a windowless hydrogen lamp

Thin films of diamond-like carbon (DLC) have been deposited using a novel photon-enhanced chemical vapour deposition (photo-CVD) method. This low energy method may be a way to produce better interfaces in electronic devices by reducing damage due to ion bombardment. Methane requires high energy photons for photolysis to take place and these are not transmitted in most photo-CVD methods owing to the presence of a window between the lamp and the deposition environment. In our photo-CVD system there is no window and all the high energy photons are transmitted into the reaction gas. Initial work has proved promising and this paper presents recent results. Films have been characterized by measuring electron energy loss spectra, by ellipsometry and by fabricating and testing diode structures. Results indicate that the films are of a largely amorphous nature and are semiconducting. Diode structures have on/off current ratios of up to 10 6.

Photo-Deposition of Hydrogenated Amorphous Silicon on Downstream Substrates Using an Upstream Windowless Hydrogen Lamp

An upstream 19 cm diameter disc-shaped hydrogen plasma has been used to deposit hydrogenated amorphous silicon films on 7.5 cm diameter wafers placed 10 cm downstream with 10 percent thickness variation. The disk plasma may offer an alternative to radio frequency excitation and this study is the first in that direction. The films have an optical band gap of 1.75 eV and an optimum photosensitivity of 2×105. The total hydrogen content was 20 at.%. There is one SiH bond for every 20 Si-H bonds. A 42 cm diameter hydrogen disk plasma has also been constructed and characterized as regards uniformity of optical emission.

Summary Abstract: Role of ions in carbon-film deposition by a windowless hydrogen lamp

Summary Abstract: Role of ions in carbon-film deposition by a windowless hydrogen lamp

Excitation of copper atoms by electron impact

In the present paper, we report on the results of an investigation of absolute effective electron-impact excitation cross sections for the copper atom. All the measurements were carried out by the method of intersecting electronic and atomic beams with photoelectric recording of radiation both in a synchronous-detectlon regime and in adc amplification regime. The intensity Of the atomic beam was determined by a radio-englneerlng method [3] and also according to the value of the ionic current. The data on the value of the ionization cross section were taken from [4]. The concentration of the atoms in the beam-intersection zone did not exceed i0 I~ atoms/cm 3, and the density of the electronic current was 0.003-0.007 A/ cm 2 with nonuniformity up to an energy of 1.0 eV (for 90% electrons). The residual pressure in the collision chamber was 10 -6 tort during the measurements. As was shown by control experiments, the luminescence spectrum of the resldual-gas molecules had no effect on the excitation functions of the copper atoms. Absolute measurements were carried out by comparing the line intensities with the radiation of an SI-8-200 tungsten ribbon-filament lamp and a VS FU-3 hydrogen lamp.* According to our evaluations, the relative error in the determination of the absolute excitation cross sections did not exceed 30% for the spectral region of 360-600 nm and 40% for the spectral region of 220-360 nm.

Spectroradiometric calibration techniques in the far ultraviolet: a stable emission source for the Lyman bands of molecular hydrogen

The problems associated with making accurate spectroradiometric measurements in the far uv region are sketched briefly. The equipment and methods that were developed for providing absolute sensitivity calibration of an Apollo 17 far uv spectrometer are described. The absolute reference standards were photoelectric diodes calibrated at the National Bureau of Standards. A complete vacuum optical facility, which included a premonochromator and stable uv light sources, was developed to calibrate the Apollo 17 instrument, and it has been used for a number of other tasks. Absolute radiometric calibrations between about 1200 A and 1700 A were performed with an absolute accuracy of +/-10%. The light source, which was designed to provide a very stable light output, is a low-pressure molecular hydrogen lamp in which the pressure is stabilized by thermal control of uranium hydride powder. Individual emission lines of the Lyman molecular band system of H(2) are used for calibration purposes. The lamp also copiously emits the 1215.7-A line (Lyalpha) of atomic hydrogen.

Electronic Absorption Spectrum of 2,4-Dibromoaniline in Vapor

The near ultraviolet absorption spectrum of 2,4-dibromoaniline in vapor phase has been photographed for the first time on a Q-24 Zeiss Medium Quartz Spectrograph. The quartz to Pyrex graded seal cells were used. The conventional hydrogen lamp was the source of continuous radiation. The tube lengths were varied from 50 to 125 cm and the temperatures from 30° to 80°C. The sharp bands appear with a cell of length 100 cm at the temperature 43°C. The spectra were photographed on Kodak B10 plates.

A Gas Discharge Lamp for the Extreme Ultraviolet

A gas discharge lamp is described suitable for producing the many-lined spectrum of hydrogen (85-160 nm) and the Hopfield continuum in helium (60-100 nm). It was designed for use with a window-less monochromator to study photoionization and operates at pressures below 50 Torr. The hydrogen lamp has a mode of operation which concentrates the discharge into the monochromator entrance slit.

Measurement of the Fluorescence Lifetime of Chlorophyll a In Vivo

New measurements have been made of fluorescence lifetime (tau) of chlorophyll a in the algae Chlorella pyrenoidosa, Porphyridium cruentum, Anacystis nidulans, and in spinach chloroplast. tau-values of 0.6 and 0.7 nsec were obtained with green plants. Anacystis and Porphyridium gave a tau of 0.5 nsec. The previously described two stage decay of fluorescence in vivo in these organisms could not be confirmed. This observation could have been caused by a second wave of light emission from the exciting hydrogen lamp (not detected in earlier work). The lifetimes found in this study (calculated, as before, by the method of convolution integrals) were close to those found by other observers for "low" excitation intensities; the value first reported from this laboratory (1.0-1.7 nsec) may have corresponded to "high" excitation intensity.

Dissociative Electron Attachment inI2Vapor at 295° K

Two-body electron attachment frequencies have been determined for iodine in the presence of helium using microwave cavity techniques where initial ionization is produced by a single light pulse from a hydrogen lamp. The value for the electron attachment coefficient determined from the attachment frequency data is $k=1.8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ ${\mathrm{cm}}^{3}$ ${\mathrm{sec}}^{\ensuremath{-}1}$ at 295\ifmmode^\circ\else\textdegree\fi{}K. The ambipolar diffusion of iodine ions in helium has also been examined at this temperature, and a value for ${\mathrm{D}}_{a}+p$ of 730 ${\mathrm{cm}}^{2}$/sec Torr was obtained. Electron-density decay rates observed using a repetitive-pulse technique were higher than those observed using the singlepulse technique for a given iodine vapor pressure. Possible effects on the electron diffusion rate as a result of the presence of negative ions are discussed.