Inductively coupled plasma reactor

Fig. 11 Schematic diagram of an inductively-coupled plasma reactor.

Delzeit L, McAninch I, Cruden BA, Hash D, Chen B, Han J, et al. Growth of multiwall carbon nanotubes in an inductively coupled plasma reactor. J Appl Phys 2002 91 6027-33. 

One way to fabricate such a reactor is by deep reactive ion etching (DRIE) with a time-multiplexed inductively coupled plasma etcher (most details on fabrication are given in [77]) [7, 77, 78]. Regions of major importance such as the retainers are etched through to avoid differences in stmctural depth which may cause uneven flow. To generate various channel depths in one design, both front-side and back-... 

Until now, little attention has been given to the analysis of ancient copper alloys with LA-ICP-MS. This type of material is usually analyzed with fast or instrumental neutron activation analysis (FNAA or INAA), particle induced X-ray emission (PIXE), X-ray fluorescence (XRF), inductively coupled plasma-atomic emission spectrometry or inductively coupled plasma-atomic absorption spectrometry (ICP-AES or ICP-AAS). Some of these techniques are destructive and involve extensive sample preparation, some measure only surface compositions, and some require access to a cyclotron or a reactor. LA-ICP-MS is riot affected by any of these inconveniences. We propose here an analytical protocol for copper alloys using LA-ICP-MS and present its application to the study of Matisse bronze sculptures. 

Besser et al. [86] studied the reaction in a silicon reactor fabricated by applying MEMS technology, namely photolithography and DRIE by inductively coupled plasma. Each reactor incorporated dual gas inlets, a pre-mixer, a single reaction channel and an outlet zone where the product flow was cooled (see Figure 2.54). The single channel was 500 pm wide, 470 pm deep and 45 mm long. 

Chlorine and bromine atoms were generated using UV and visible photolysis of molecular chlorine and bromine, respectively, in addition to UV (300 < k < 400 nm) photolysis of chloroacetyl chloride and dibromomethane. The reaction products were analyzed in the gas-phase, in suspended aerosols and on the wall of the reactor using MS, GC-MS and inductively coupled plasma mass spectrometry (ICP-MS). The major products identified were HgCb and HgBr2 adsorbed on the wall. Suspended aerosols, collected on the micron filters, contributed to less than... 

There are two important questions which may readily be addressed by ESCA. Firstly, what is the rate of deposition of the polymer film at a given site in a plasma reactor and secondly how does the structure depend on the site of deposition To illustrate the great power of the technique in answering these questions we consider here a recent detailed investigation of the inductively coupled plasma polymerization of pentafluorobenzene (13). 

A fit-for-purpose estimate of the individual activities is needed for waste disposal purposes and calculation of neutron activation of precursors is often the simplest method, where contamination is unimportant. For H, the concentration of the Li precursor is required. The mobile nature of is a complicating factor since, in principle, it may remain in situ or diffuse within the bulk material. The aim of this work was to provide some answers to the above questions by determining the concentrations of Li in reactor steels and to compare the predicted levels of with values measured in reactor surveillance specimens. Preliminary attempts to measure Li in reactor steels by ICP-OES (inductively coupled plasma - optical emission spectroscopy) were not successful and... 

Vanadium molecular size distributions in residual oils are measured by size exclusion chromatography with an inductively coupled plasma detector (SEC-ICP). These distributions are then used as input for a reactor model which incorporates reaction and diffusion in cylindrical particles to calculate catalyst activity, product vanadium size distributions, and catalyst deactivation. Both catalytic and non-catalytic reactions are needed to explain the product size distribution of the vanadium-containing molecules. Metal distribution parameters calculated from the model compare well with experimental values determined by electron microprobe analysis, Modelling with feed molecular size distributions instead of an average molecular size results in predictions of shorter catalyst life at high conversion and longer catalyst life at low conversions. 

Chemical vapor deposition (CVD) using TiC was used to prepare Ti/Si02, Ti/MCM-41, and Ti/MCM-48 catalysts. These catalysts were characterized by inductively coupled plasma-atomic emission spectroscopy (ICP-AES), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, nitrogen adsorption, and were used to catalyze the epoxidation of propylene to propylene oxide (PO) with in situ prepared ethylbenzene hydroperoxide (EBHP). CVD time and CVD temperature affected the catalyst performance significantly. The optimum temperature range was 800-900 °C, and the optimum deposition time was 2.5-3 h. The maximum PO yields obtained in a batch reactor were 87.2, 94.3, and 88.8% for Ti/Si02, Ti/ MCM-41, and Ti/MCM-48, respectively. Ti/MCM-41 had higher titanium... 

A cross-sectional diagram of the reactor is presented in Figure 2. The isotherms indicated are those determined spectroscopically by Reed (32), and are representative of conditions in this study. Eckert and coworkers (7) have extended this work to spectroscopic observations of induction-coupled plasmas in both air and argon. Conditions of local thermodynamic equilibrium were approached and temperatures above 6000°K. were measured. No direct temperature measurements were attempted in the present study. 

Inductively coupled plasma (ICP) reactors (Fig. 20a) are particularly attractive because their design is relatively simpler and they are easily scaleable to large diameter substrates [84, 85]. In ICPs, the plasma is excited in a cylindrical chamber (r, 2,0) by a solenoidal or planar (stovetop-type) coil powered at radio frequencies, for example 13.56 MHz. The coil current induces a time-varying magnetic field which in turn induces an azimuthal (in the 0-direction) electric field that couples power to the plasma, i.e., heats the plasma electrons. For common excitation frequencies (less than the plasma frequency), the electromagnetic fields are absorbed by the plasma within the skin depth. For typical conditions, fields penetrate a few cm into the plasma. The power is deposited non-uniformly in the shape of a toroid (see also Fig. 

Fig. 20. High density plasma (HDP) reactor configurations. Inductively coupled plasma (ICP) (a), helical resonator (b), electron cyclotron resonance (ECR) (c) and helicon (d) reactors. After [11].

Earlier methods used to determine mercury in biological tissue and fluids were mainly colorimetric, using dithizone as the com-plexing agent. However, during the past two to three decades, AAS methods - predominantly the cold vapor principle with atomic absorption or atomic fluorescence detection - have become widely used due to their simplicity, sensitivity, and relatively low price. Neutron activation analysis (NAA), either in the instrumental or radiochemical mode, is still frequently used where nuclear reactors are available. Inductively coupled plasma mass spectrometry (ICP-MS) has become a valuable tool in mercury speciation. Gas and liquid chromatography, coupled with various detectors have also gained much importance for separa-tion/detection of mercury compounds (Table 17.1). 

Boulyga, S. F., Becker, J. S., Matusevitch, J. L., and Dietze, H. J. 2000. Isotope ratio measurements of spent reactor uranium in environmental samples by using inductively coupled plasma mass spectrometry. Int J Mass Spectrom 203(1-3), 143-154. 

Environmental samples offer a challenge to the analytical chemist because of the matrices involved. These include, among others, fresh- and seawater, sediments, marine and biological specimens, soil, and the atmosphere. For determining trace concentrations of vanadium in these complex matrices, preconcentration and separation techniques may be required prior to instrumental analysis. Hirayama et al. [14] summarize the various preconcentration and separation techniques including chelation, extraction, precipitation, coprecipitation, ion exchange in conjunction with the instrumental method of spectrometry, densitometry, flow injection, NAA, AAS, X-ray fluorescence, and inductively coupled plasma atomic emission spectrometry (ICPAES). While NAA offers great sensitivity and selectivity, its application is limited by the number of research reactors available worldwide. 

Ray et al. [24] treated Cloisite 20A (montmorillonite modified with dimethyl-ditallow-containing approximately 65% Cig, 30% Cis, and 5% Ci4-ammonium cation chains) with a MAO solution, after vacuo-drying at 100 °C. The resulting MAO-treated clay was subsequently used for ethylene polymerizahon in the presence of a late transition metal catalyst (2,6-bis[l-(2,6-diisopropylphenylimino)ethyl] pyridine iron(ll) dichloride) and additional MAO in a glass reactor. They compared the result with homogeneous polymerization with the same catalyst in the presence of Cloisite 20A and observed that the supported catalyst was more efficiently exfoliated than when only a mixture of catalyst and clay was used. This comparison led them to conclude that at least some of the active centers resided within the clay galleries. Inductively coupled plasma (ICP) measurements showed that all MAO and catalyst remained in the solid catalyst after drying. 

Similarly, Baers and Harsanen (1993) have determined the specific Nb activities in reactor pressure vessel steel (containing niobium in the ppm range) and plating ( 1% Mb). Niobium was isolated from the other radionuclides by ion exchange chromatography and ""Nb measured by liquid scintillation spectrometry niobium mass in the samples was determined by inductively-coupled plasma mass spectrometry. In this way, it was possible to rule out interferences caused by other radionuclides. However, the data to be used for the calculation of fast neutron fluence can be impaired by ""Nb which is formed by decay of Mo which is an (n,y) product of stable Mo. This interference becomes significant when the... 

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