In dc glow discharge mass spectrometry, the addition of small amounts of H2 to pure Ar as discharge gas has greatly increased the ion intensities of elements compared with the conventional method using
pure Ar. This phenomenon was also observed for the addition of H2 to pure Kr. The reason for the increase of the ion intensities of elements was studied by using a Kr gas mixture containing
0.2% (v/v) H2. The ion intensities of the elements P, Se and As (whose first ionization potentials are higher than the energy levels of
the excited state of Kr) did not increase even if the Kr/H2 gas mixture was used. The results show that the addition of H2 significantly contributed to increasing the number of metastable argon or krypton atoms (Penning ionization).
Received: 4 November 1995/Revised: 5 January 1996/Accepted: 10 January 1996 相似文献
In dc glow discharge mass spectrometry, the addition of small amounts of H2 to pure Ar as discharge gas has greatly increased the ion intensities of elements compared with the conventional method using
pure Ar. This phenomenon was also observed for the addition of H2 to pure Kr. The reason for the increase of the ion intensities of elements was studied by using a Kr gas mixture containing
0.2% (v/v) H2. The ion intensities of the elements P, Se and As (whose first ionization potentials are higher than the energy levels of
the excited state of Kr) did not increase even if the Kr/H2 gas mixture was used. The results show that the addition of H2 significantly contributed to increasing the number of metastable argon or krypton atoms (Penning ionization).
Received: 4 November 1995/Revised: 5 January 1996/Accepted: 10 January 1996 相似文献
The addition of hydrogen to a direct current (dc) - argon glow discharge (GD) coupled to a time of flight mass spectrometer has been studied using a fixed voltage between the electrodes and a fixed discharge pressure. Hydrogen contents investigated were 0.5%, 1% and 10% v/v in the argon discharge and the samples under study consisted of a copper-base, a nickel-base and an iron-base homogeneous materials. Also, the in-depth profile analysis of a tin plate was investigated. Results have shown that hydrogen addition gives rise to significant changes in the slope of the linear relationship between the electrical current and the discharge voltage. Clearly, the electrical resistance of the discharge at the typical operation voltages in the interval 600–1000 V increases with hydrogen added to pure argon.A decrease of the sputtering rates was observed the higher the hydrogen concentrations. Besides, the “reduced sputtering rates”, i.e. the sputtering rates divided by the corresponding electrical current, were also lower for the H2/Ar discharges than for pure argon. However, the analytical ion signals observed using discharge voltages higher than 900 V turned out to be higher in a 0.5% H2/Ar discharge than in pure argon for the copper and nickel materials. Besides, for the three samples investigated the ion yields were from 1.5 up to 3 times higher in 0.5% H2/Ar discharges as compared to the pure argon.Finally, the effect of 0.5% H2 addition to the Ar discharge on the in-depth profile of a tin plate has also been investigated. As compared to the use of a pure Ar GD, higher sensitivity for major and minor components of the coating were observed without loss of the relative depth resolution achieved. 相似文献
Radio-frequency glow discharge mass spectrometry (RF GDMS) has been applied to the determination of trace elements in ceramic perovskite layers (La0.65Sr0.3MnO3) using synthetic standards. For the preparation of these standards high-purity powder of the basic material (La0.65Sr0.3MnO3) was doped with trace elements in concentrations from 20 to 500 μg/g and the mixture was pressed to compact samples. The resulting calibration curves and the calculated relative sensitivity factors (RSF) differed only from 0.4 to 2 for different elements. For nearly all elements the standard deviations in the determination of trace elements in La0.65Sr0.3MnO3 were better than 15% and detection limits (using the 3σ-criterion) were below 10 μg/g. Changes of the discharge parameters (RF power, pressure of the discharge gas (Ar) in the RF glow discharge) have no significant influence on the sensitivity to elements. 相似文献
The Ar‐ions intermittent‐etching technique was successfully incorporated during the deposition of glow discharge polymer (GDP) films. The ionic components and ion energy distributions (IEDs) of C4H8/H2 and C4H8/H2/Ar plasma were diagnosed by an energy‐resolved mass spectrometer, respectively. The Fourier transform infrared spectroscopy, scanning electron microscope, and white‐light interferometer were used to studying the chemical structure, surface morphology, and roughness of the GDP films, which are deposited with the various time of Ar‐ions intermittent etching. With the introduction of Ar into the chamber, the intensity of the C H absorption peaks becomes weak and the large‐mass C H species were ionized and dissociated from the mass spectrometer results. The surface roughness of GDP films are decreased with Ar‐ions intermittent etching, the lowest surface roughness (Rq) is only 33.6 nm when the intermittent cycle is 60 minutes/15 minutes. The highest sp3CH3 (sym) absorption peaks are attributed to samples also with 60‐minute/15‐minute intermittent cycle, which shortens the length of the carbon chain and reduces the probability of the cluster formations. 相似文献
A quick spectroscopic method of rotational temperature determination based on the low-resolution emission spectrum of the N2 (v=2v=()) vibronic band profile of the second positive system iras developed. The new method of molecular gas temperature determination was used in an rf glow discharge excited in N2 and N2 + Ar + B2 H6 gas mixture at u pressure range 500–13011 Pa. This method of molecular gas temperature measurement is applicable to nonisothermic plasmas used in plasma-chemical reactors. 相似文献
This work reports laser ionization combined with Time-Of-Flight (TOF) mass spectrometry investigation on intermediate species
in the hydrocarbon plasma of atmospheric-pressure fast-flow pulsed dc-discharge. All neutral intermediate species including
transient radicals from benzene/Ar discharge have been characterized by a molecular beam sampling combined with TOF mass spectrometry.
This shows that with a hydrocarbon gas mixture of 0.3% C6H6 in Ar discharge the intermediate species consist of simple radicals (such as C2, C5H5, C7H7) and polycyclic organic molecules (C10H8, C13H10, C14H10). Theoretical studies on total energies and ionization potentials of the intermediate species have been carried out using
the hybrid density functional theory. Effect of the ionization potential on mass spectral intensity has been discussed. Based
on the observed data, the possible major neutral reaction channels of the plasma chemistry have been discussed. The developed
experimental method has implications in volatile organic compounds removing and impurities diagnosis in Tokamak edge-plasma. 相似文献
The influence of glow discharge plasma in oxygen and argon and high-frequency discharge plasma in hydrogen on the activity of the AP-64 (Pt/γ-Al2O3) catalyst in the dehydrogenation of cyclohexane was studied. The catalytic experiments were performed in a flow unit and under static conditions in a vacuum. Under flow conditions, catalyst treatment with plasmas in O2 and Ar decreased the yield of benzene by ~50% but strengthened temperature hysteresis because of the formation of active carbon on the surface of the catalyst. Under static conditions, argon plasma and high-frequency discharge H2 plasma multiply increased the rate of the reaction because of an increase in the number of active centers, whereas an oxygen plasma decreased the rate of the reaction by two times because of an increase in activation energy. The determination of the order of the reaction led us to suggest that the stage scheme of the reaction did not change after plasma chemical catalyst treatments. 相似文献
Plasma polymerizations of mixture of acetylene-N2, acetylene-H2O, were investigated by using an electrodeless glow discharge from a 13.5-MHz radiofrequency source. Properties of plasma polymers were examined as functions of mole ratios of N2 and/or H2O to acetylene. The concentration of trapped free radicals and the internal stress in a plasma polymer decreased as the mole ratio of N2 or H2O increased. Water showed the most pronounced effects in those properties at the mole ratio of 0.3. Gas permeabilities increased by the copolymerization of N2 and/or H2O. Surface energies were also investigated by analysis of contact angles of liquids. Copolymerization of N2 caused a remarkable increase in polar contribution of surface energy. Some fundamental aspects of flow-rate pressure relationship of mixed gases are presented. 相似文献
The vibrational relaxation of gaseous H2 in mixtures with He, Ne, Ar, and Kr was studied by the laser Schlieren technique in incidents shock waves at 1350–3000 K. From the results of 155 experiments the following standard relaxation times for self-relaxation of H2 and relaxation of H2 by He, Ne, Ar and Kr were obtained: pτ is in atm s, and the qouted uncertainties are standard deviations. The results for H2/H2 and H2/Ar are in very good agreement with previous results of Kiefer and Lutz, and the extrapolated for H2/H2, H2/He and H2/Ar agree very well with low temperature data Ducuing.The linear mixture rule for a additivity of relaxation rates was found to hold, to within experimental accuracy, for the mixtures studied in the present work. 相似文献
Decomposition of CF4 by glow-discharge and arc plasmas was studied using a tubular quartz reactor, a disk type, and a T-type quartz reactor. The effects of different metal electrodes, input voltage, and reactor type on the efficiency of CF4 total destruction (DRE) were studied. The T-shape reactor was more efficient in CF4 destruction than either the disk or tubular type due to a combined effect of glow discharge and arc plasmas. Several hydrogen and oxygen sources, such as H2O, H2, O2, and CH4, were used to convert CF4. Using H2 and O2 as the hydrogen and oxygen sources presented better DRE than using H2O. The effect of different hydrogen and oxygen sources on the conversion of CF4 followed the trend: (H2 + O2) > (CH4 + O2) > H2O. The maximum DRE of 95% was observed with 0.5% CF4 using H2 and O2. A mass spectrometer and an emission spectroscope equipped with a charge-coupled detector (CCD) were used to characterize the products and intermediates. Mass spectrometric studies indicated that the reaction products were HF, CO2, and trace amounts of NO. N2 first negative and second positive emission lines were observed in the glow discharge plasmas as well as in the arc plasmas of N2. However, C and F intermediates were observed only in arc plasmas of CF4. Reactions occurring in the glow discharge plasmas and arcs seem to follow different mechanisms. 相似文献
In a capacitively coupled discharge with external electrodes, He, H_2, N_2 or Ar were used as plasmagas, polymerization of octafluorocyclobutane was carried out under different conditions by varyingdischarge power, pressure, plasma gas and plasma-gas/monomer ratio. Structure of polymerizedproducts was characterized by IR spectroscopy and ESCA measurement. It was found that therewere six elements in the products, i.e. C, F, Si, O, N and H. The probably existed groups in poly-mers wer investigated. By analyzing the resolved peaks of C_(1S) region in ESCA spectra, effect of thereaction conditions on degree of branching of the polymerized products and the relationship of thepolymer structure wth the mechanism of the competitive ablation and polymerization process werestudied. In addition, polymer deposition process occurring in glow discharge was discussed. 相似文献
We herein proposed a sample introduction technique based on solution cathode glow discharge(SCGD)of a portable design for inductively coupled plasma-optical emission spectrometry(ICP-OES) and its application in sensitive determination of mercury. The products from SCGD containing mercury vapor, were transported by an Ar flow to ICP spectrometer for detection. A gas liquid separator(GLS) and a dryer were used to condense and remove most of the accompanying moisture, which greatly improved both th... 相似文献
A study about the effect of nitrogen in the calibration curves of a series of analytical emission lines has been carried out
in this work. Fifteen reference materials with different matrices (Fe, Al, Zn, Cu and Ni) were used (three of these reference
materials contain nitrogen in their composition) and plots of intensity versus the product “sputtering rate times element
concentration” were constructed for emission lines of the analytes considered in this work (Al, Fe, Cu, Cr, C, Mo, Zn, Si,
Ti and Ni). Two different fits were performed in each plot, first considering only the points corresponding to samples without
nitrogen in their composition and secondly including all the points. The results show almost negligible differences in the
emission yields calculated. On the other hand, a mixture of Ar containing 0.5% N2 was employed to check if the nitrogen effect was present at higher concentrations than those expected in analysis when samples
with high nitrogen concentrations are used. Differences between the slopes of the calibration curves with the Ar/N2 and pure Ar discharges were obtained (up to 30%). A study of the molecular bands recorded in the spectra when nitrogen is
present in the discharge and determination of the resulting interferences on the analytes have been performed.
Figure Glow discharge powered with radiofrequency energy 相似文献
Contents and distributions of polycyclic aromatic hydrocarbons (PAHs) in the depositions were investigated and discussed in a MTBE/Ar, a MTBE/O2/Ar and a MTBE/H2/Ar plasma systems. A radio-frequency (RF) plasma system was used to produce the depositions under the designed operational condition. The identification and quantification of PAHs was accomplished by using a GC with a mass selectivity detector (GC/MS). Results indicated that when the input power controlled at high wattage (70 W) in the three systems, the contents of total-PAH in the MTBE/Ar system are higher than those of total-PAH in other system with adding O2 or H2. The comparison of three systems indicated the formation and accumulation of PAHs in the MTBE/Ar system is easier than other systems. At high input power wattage, when the MTBE/Ar mixture added O2 or H2, the domain pattern was shifted from both 3- and 4-ring PAH to 2-ring PAH. As far as the total-PAH content is concerned, the MTBE/Ar system at 70 W was found to have the highest mean total-PAH content (1540 g/g), while the MTBE/O2/Ar system at 20 W had the lowest mean total-PAH content (44.4 g/g). 相似文献
The present paper describes radiochemical separation procedures developed for the determination of the elements As, Cr, Hg, Sb and Se in biological reference materials. The methods chosen utilize ion exchange, retention on inorganic exchangers and solvent extraction techniques for the isolation of the elements of interest. These procedures are more rapid than previously used methods, such as distillation and precipitation. As to the sample dissolution, the following procedures were tested using radioactive tracers and reference materials: treatment of the materials in teflon bombs with a mixture of HNO3+H2SO4 or HNO3 only in a normal oven, and with HNO3 in a microwave oven using specially designed digestion bombs. 相似文献
The influence of the controlled addition of N2 and of O2 to Ar on the analytical parameters of a dc glow discharge has been investigated for bulk samples of the pure metals Al, Ti, Fe, Ni, Cu, and Ag. The constant voltage discharge mode at 1000 V was applied with a mean power of about 1 W/mm2. The N2 and O2 concentrations in the discharge gas Ar were varied in the range 0–3 mass-%, corresponding to a partial pressure of about 4 · 10?3 hPa. The general effect of the gaseous addition is the decrease of the sputtering rate with an increasing concentration of N2 or O2. Atomic processes, which might be responsible for the observed effects, are discussed. 相似文献