Glow discharge polymerization of tetramethylgermanium

A glow discharge polymerization technique was applied in the preparation of germanium-containing polymers. The colorless and transparent polymer films formed from tetramethylgermanium (TMG) were investigated by elemental analysis, infrared (IR) spectroscopy, and ESCA. The reaction of TMG was accompanied by the rupture of bonds between Ge and CH₃ groups which led to mixtures of polymers that consisted of CH₃, CH₂, Ge? CH₃, Ge? O? C, and Ge? O? Ge groups and germanium metal. Most Ge species present at the outermost layers of the films were oxidized subsequently by air, whereas the Ge species at the inner layers still existed as Ge metal. This film-forming process can be explained by the concept of atomic polymerization proposed by Yasuda.

1 See H. Yasuda, J. Polym. Sci. Macromol. Rev., 16 , 199 (1981).

     

Glow discharge polymerization of tetramethylsilane investigated by infrared spectroscopy and ESCA

The influence of operating conditions (W/FM parameter: W input energy of rf power; F flow rate of monomer; M molecular weight of monomer) on glow discharge polymerization of tetramethylsilane (TMS) was investigated by infrared spectroscopy and ESCA. Elemental analyses showed that the compositions of the polymers formed strongly depended on the level of the W/FM parameter, i.e., whether the W/FM value was more or less than 190 MJ/kg. The infrared spectra indicated that these polymers were composed of Si? H, Si? O, Si? C, Si? CH₃, and Si? CH₂ groups, and that there was no significant difference in structural features between polymers prepared at W/FM parameters of more or less than 190 MJ/kg. ESCA spectra (C_1s and Si_2p core-level spectra) showed that the polymers included carbonized carbon, aliphatic carbon Si? C, C? O, Si? O, and SiO₂ species, and that the sum of carbonized and aliphatic carbons reached more than 50%. Raising the W/FM value increased the formation of the carbonized carbon but did not influence the formation of Si units such as Si? C and Si? O groups. From this evidence the rupture of Si? CH₃ bonds in the polymer forming process is emphasized. The magnitude of the W/FM parameter may be related to the detachment of hydrogen from the aliphatic carbon units.     

Glow discharge polymerization in the mixture of tetramethylsilane and ammonia gas

Colorless, transparent, and filmy polymers prepared from mixtures of tetramethylsilane (TMS) and ammonia gas (NH₃) were investigated by elemental analysis, infrared (IR) spectroscopy, and ESCA. These polymers contained a large amount of nitrogen residues in the form of amine, amide, and amine oxide groups. Their concentration varied with the composition of the starting TMS/NH₃ mixtures. The mixing of NH₃ gas with TMS influenced the chemical state of Si residues and accelerated the oxidation of Si atoms to form silicon oxides such as SiO, Si₂O₃, and SiO₂. The polymers formed by glow discharge polymerization in the TMS/NH₃ mixtures were combinations of Si- and N-containing polymers and silicon oxides.     

Glow discharge mass spectrometry

Over the past twenty years or so, glow discharge mass spectrometry (GDMS) has become the industry standard for the analysis of trace elements in metals and semiconductors. A review of its history is followed by a picture of the present situation and a look to where the future may lie. Applications are summarised, including the ability of GDMS to offer depth-resolved data and non-conductor analysis, and the well-documented quantitative nature of the results is reviewed. The effects resulting from the physical properties of the analyte material are discussed at length. Finally, recent work such as fast flow sources and pulsed glow discharges is reviewed.     

Glow discharge deposition of tetramethylsilane films

Thin films have been deposited in a low-pressure glow discharge of tetramethylsilane. The study of the deposition kinetics has shown that the determining parameter is the ratio W/P_TMS of the RF power over the TMS partial pressure. The role of oxygenated impurities present in the starting monomer is emphasized. High values of the W/P_TMS ratio give films of low oxygen content as shown by IR spectroscopy measurements (<5% of Si-O bonds). These films have high densities (1.7–2 g/cm³) and refractive indices (1.7) and are similar to amorphous hydrogenated silicon carbide films. On the contrary, low values of W/P_TMS result in the formation of a significant amount of Si-O bonds which are formed at the expense of Si-H bonds. The deposited films show lower densities (0.98–1.6 g/cm³) and lower refractive indices (1.47). It is postulated that this oxygen, which affects the kinetics and the film properties, comes from oxygenated pollutants (H₂O) carried along with the monomer, and that its concentration depends on the temperature of the TMS cooling bath.     

Glow characterization in direct current plasma polymerization of trimethylsilane

Plasma polymerization of trimethylsilane (TMS) was carried out in a direct current (dc) glow discharge and was investigated by optical photography and plasma diagnostic techniques including optical emission spectroscopy and residual gas analysis. The nature of the glow formed in TMS discharge, which deposited plasma polymers, was significantly different from that of a simple gas such as Ar. In an Ar discharge, the dominant glow was the well known negative glow, which developed at a distinctive distance from the cathode, whereas the cathode surface remained in the dark space. In strong contrast to this situation, in TMS dc discharge the dominant or primary glow was the cathode glow, which appeared at the cathode surface. At a similar location where the Ar negative glow appeared, a very feeble glow as a secondary glow was also observed in TMS glow discharge. The deposition results and plasma diagnosis data evidently indicated that in TMS glow discharge, the cathode glow resulted from the low‐energy electron‐impact dissociation of TMS molecules that creates polymerizable species, but the negative glow was related to nonpolymerizable species such as hydrogen atoms and molecules. In this article, the cathode glow formed in glow discharges of organic compounds was designated as the dissociation glow according to its underlying plasma reactions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1042–1052, 2004     

Glow discharge in microfluidic chips for visible analog computing

Here we present a novel visible analog computing approach for solving a wide class of shortest path problems. Using a microfluidic chip for computation, based on the lighting up of a glow discharge, the solution to maze search problems, the solution of a network shortest path and k-shortest paths problems and the practical application of finding the shortest paths between several landmarks from a street map are presented. The solution and visible display (in real time) for these problems shows only a small difference in practical problem solving time among problems with varying differences in size.     

Glow discharge growth of SnO2 nano-needles from SnH4

Single crystalline SnO(2) nano-needles with length up to 6-7 microm and diameter less than 300 nm are synthesized on an Au-coating porous silicon substrate from SnH(4) source via a glow discharge process.     

Glow discharge electron impact ionization source for miniature mass spectrometers

A glow discharge electron impact ionization (GDEI) source was developed for operation using air as the support gas. An alternative to the use of thermoemission from a resistively heated filament electron source for miniature mass spectrometers, the GDEI source is shown to have advantages of long lifetime under high-pressure operation and low power consumption. The GDEI source was characterized using our laboratory's handheld mass spectrometer, the Mini 10. The effects of the discharge voltage and pressure were investigated. Design considerations are illustrated with calculations. Performance is demonstrated in a set of experimental tests. The results show that the low power requirements, mechanical ruggedness, and quality of the data produced using the small glow discharge ion source make it well-suited for use with a portable handheld mass spectrometer.     

Glow discharge mass spectrometry — A versatile tool for elemental analysis

Summary Among recent MS techniques for elemental analysis, Glow Discharge Mass Spectrometry (GDMS) covers the field of direct analysis of conducting and semiconducting solids. In GDMS, a glow discharge in a working gas — usually Ar — at reduced pressure serves to atomize a solid sample by cathodic sputtering and to ionize the vapourized atoms. Ions are separated according to mass by a quadrupole filter (with low mass resolution) or a double focusing device (with high mass resolution). Use of a working gas implies the appearance of spectral interferences by molecular ions. Analysis may be impeded by these interferences, even in the case of high mass resolution. GDMS shows convincing analytical performance. Detection limits in the low ng/g region and even below can easily be realized. Precision is normally in the low percentage region, and a dynamic region of about nine orders of magnitude may be covered. Matrix effects are of no significant influence, and elemental sensitivities are within one order of magnitude. Semiquantitative analysis without standards is possible with limited accuracy, which is of considerable practical interest in the sub-microtrace region. Application experiences have mainly been gathered in analysis of very pure materials and semiconductors. GDMS has also been applied successfully for analytical characterization of technical surface layers.     

Glow discharge mass spectrometry-a powerful technique for the elemental analysis of solids

A high resolution glow discharge mass spectrometer for the elemental analysis of solids is described. The analytical performance is reviewed and results are presented on a wide range of materials illustrating elemental and concentration coverage, quantitation and detection limits. Comparisons with other techniques are made.     

Glow discharge source atomization for the laser-excited atomic fluorescence spectrometric studies of indium

A demountable glow discharge source has been used for the atomization of the analyte solutions deposited on graphite and copper rod cathodes. Indium atoms are sputtered-atomized from the cathode surface and are excited by a pulsed, frequency-doubled dye laser pumped by the nitrogen laser. Atomic fluorescence measurements were performed using the non-resonance fluorescence transition. The detection limits of indium in aqueous solutions (10μl) deposited on graphite and copper electrodes were 8 × 10⁻⁹ and 11 × 10⁻⁹g, respectively (8 ng and 11ng).     

Glow discharge electrolysis plasma initiated synthesis of upconversion luminescent and temperature sensitive multifunctional hydrogel

In the present work, a novel multifunctional hydrogel that simultaneously possesses strong upconversion luminescence (UL) and temperature responsibility was fabricated based on the crosslinking of hemicellulose and ricinoleic acid capped NaYF₄:Yb/Er in the presence of Poly (N-isopropylacrylamide) (PNIPAM) and polyacrylamide (PAAm) aqueous solution by using glow discharge electrolysis plasma (GDEP) initiated technique. Its structure and properties were characterized by wide angle X-ray diffraction, FT-IR spectra, scanning electron microscopy, transmission electron microscope and fluorescence spectra. The obtained hydrogel exhibited reversibly temperature-dependent UL and highly enhanced sensibility. The luminescence intensity and transmittance of hydrogel showed a sharp decrease in the range of 32–35°C. Furthermore, the luminescence intensity of hydrogel was almost not weakened after five heating-cooling cycles, which may allow their use in remote control thermosensitive switch.     

Comparisons of glow discharge polymerization between hexamethyldisilazane and trimethylsilyldimethylamine

Glow discharge polymerization between hexamethyldisilazane (HMDSZ) and trimethylsilyldimethylamine (TMSDMA) was compared by means of infrared spectroscopy and ESCA analysis. Infrared spectra pointed out differences in chemical structure between the polymers prepared from the two monomers, although the two polymers were mainly composed of resembling units such as Si? CH₃, Si? CH₂, Si? H, Si? O? Si, and Si? O? C groups: (i) The polymers prepared from TMSDMA contained N → O group, but the polymers from HMDSZ did not contain this group. (ii) Influences of the W/FM parameter (W is the input energy of rf power, F the flow rate of the monomer, and M the molecular weight of the monomer) appeared on decreasing the C? N group and increasing the C?O group in the TMSDMA system, but little influence appeared in the HMDSZ system. ESCA spectra (C_1s, Si_2p, and N_1s core levels) supported the differences between the two polymers elucidated by infrared spectroscopy, and pointed out differences in susceptibility of the Si? N bond to plasma: The N? Si sequence of TMSDMA was completely ruptured in discharge to yield polymers, and the Si? NH? Si sequence of HMDSZ remained in considerable amount.