Emission spectroscopy hydrogen

In order to relate material properties with plasma properties, several plasma diagnostic techniques are used. The main techniques for the characterization of silane-hydrogen deposition plasmas are optical spectroscopy, electrostatic probes, mass spectrometry, and ellipsometry [117, 286]. Optical emission spectroscopy (OES) is a noninvasive technique and has been developed for identification of Si, SiH, Si+, and species in the plasma. Active spectroscopy, such as laser induced fluorescence (LIF), also allows for the detection of radicals in the plasma. Mass spectrometry enables the study of ion and radical chemistry in the discharge, either ex situ or in situ. The Langmuir probe technique is simple and very suitable for measuring plasma characteristics in nonreactive plasmas. In case of silane plasma it can be used, but it is difficult. Ellipsometry is used to follow the deposition process in situ. 

Elemental composition Li 31.85%, B 49.66%, H 18.50%. The compound is dissolved in water cautiously and the evolved hydrogen is measured by GC using a TCD. The aqueous solution is treated with nitric acid and the diluted nitric acid extract is analyzed for lithium by atomic absorption or emission spectroscopy (See Lithium). 

Approximate contents of 14 minor and trace elements in oils produced from three coals by the catalytic hydrogenation process of Gulf Research and Development Co. were determined by emission spectroscopy. The results were compared with corresponding data for the original coals and the solid residues from the process. The contents of ash, sulfur, vanadium, lead, and copper are near or below the limits specified for an oil to be fired directly in a gas turbine while sodium and probably calcium are too high. Titanium appears to be somewhat enriched in the oils analyzed relative to other elements, suggesting its presence in organo-metallic complexes. 

The Bi-promoted catalysts were prepared by consecutive deposition of Bi onto a commercial 5 wt% Pt/alumina (Engelhard E 7004, Pt dispersion 0.30 determined by TEM) [7]. The reduction of bismuth-nitrate was carried out in a dilute aqueous acidic solution O10"6 M, pH = 3-4) by hydrogen. The metal content of the catalysts was determined by inductive coupled plasma atomic emission spectroscopy (ICP-AES). Preferential deposition of Bi onto Pt particles has been confirmed by TEM, combined with energy dispersive X-ray analysis (EDX) [7]. Pb-, Sn- and Ag-promoted catalysts were prepared similarly. 

This system forms highly ionized so-called Penning mixtures [12,13]. The higher excited states of Hj are partly stable and partly unstable, depending on the quantum numbers of the electron present. The stable excited states have, however, only very shallow minima of the potential curves [14]. That is the reason why no spectrum of Hj is observed for the helium plasma jet. The argon excited neutrals, on the other hand, cannot ionize hydrogen atoms or molecules, but could produce excited H2 molecules, which can be detected by optical emission spectroscopy. 

Impurities in zirconium and zirconium alloys and compounds are often determined by emission spectroscopy. Both carrier distillation techniques and poiat-to-plane methods are available (91,92). Several metaUic impurities can be determined instantaneously by this method. Atomic absorption analysis has been used for iron, chromium, tin, copper, nickel, and magnesium (93). The interstitial gases, hydrogen, nitrogen, and oxygen are most often determiaed by chromatography (81). Procedures for carbon, chloride, fluoride, phosphorus, siUcon, sulfur, titanium, and uranium in zirconium are given in the hteiatuie (81,94—96). 

The discussion of emission spectroscopy will be concluded by a description of a rather unusual application. Bay and Steiner have measured atomic hydrogen concentrations in the presence of molecular hydrogen by microwave excitation of the atomic hydrogen line spectrum. With low power fed into the gas (ca. 5 watts), there is not enough energy available for the dissociation of molecular hydrogen and subsequent excitation. Thus the measured intensities of the atomic hydrogen lines correspond to the concentrations of atoms already present in the reaction mixture. The method is curiously similar to that adopted to detect atoms and free radicals by mass spectrometry (see Section 3). 

Every line in the hydrogen spectrum corresponds to a transition between electron energy levels. Spectral lines from hydrogen emission spectroscopy are shown at right and in the table below. Please see Skill 17.7 for additional information on atomic spectra. 

Phosphorus can serve as a benehcial adjunct or as a deleterious agent. There are several test methods for the determination of phosphorus. In addition to the three test methods described here, reference should also be made to multielement analysis methods such as inductively coupled plasma atomic emission spectroscopy (ICPAES) (ASTM D-4951, ASTM D-5185) and X-ray fluorescence (XRF) (ASTM D-4927, ASTM D-6443) described above in this guide. Phosphorus can also be determined by a photometric procedure (IP 148) or by a test method (ASTM D-1091) in which the organic material in the sample is destroyed, phosphorus in the sample is converted to phosphate ion by oxidation with sulfuric acid, nitric acid, and hydrogen peroxide, and the magnesium pyrophosphate is determined gravimetrically. Another method (ASTM D-4047, IP 149) in which the phosphorus is converted to quinoline phosphomolybdate is also available. 

The ground and electronically excited states of o-hydroxybenzaldehyde and its non-hydrogen bounded photorotamer have been characterized in rare gas matrices at 12K 2o. Absorption and fluorescence spectra and excited state lifetimes have been determined for S, states of hydroxy- and amino-substituted naphthaquinones and anthraquinones. The absorption and emission spectroscopy as well as the photochemistry, of the important group of 1,10-anthraquinones and its derivatives have recently been reviewed. ... 

Chance, K.V., D.G. Johnson, W.A. Traub, and K.W. Jucks, Measurement of the stratospheric hydrogen peroxide concentration profile using far infrared thermal emission spectroscopy. Geophys Res Lett 18, 1003, 1991. 

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