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61.
Size-related vaporisation and ionisation of laser-induced glass particles in the inductively coupled plasma 总被引:1,自引:0,他引:1
Ongoing discussions about the origin of elemental fractionation occurring during LA-ICP-MS analysis show that this problem is still far from being well understood. It is becoming accepted that all three possible sources (ablation, transport, excitation) contribute to elemental fractionation. However, experimental data about the vaporisation size limit of different particles in the ICP, as produced in laser ablation, have not been available until now. This information should allow one to determine the signal contributing mass within the ICP and would further clarify demands on suitable laser ablation systems and gas atmospheres in terms of their particle size distribution.The results presented here show a vaporisation size limit of laser induced particles, which was found at particle sizes between 90 nm and 150 nm using an Elan 6000 ICP-MS. Due to the fact that the ICP-MS response was used as evaluation parameter, vaporisation and ionisation limits are not distinguishable.The upper limit was determined by successively removing the larger particles from the aerosol, which was created by ablation of a NIST 610 glass standard at a wavelength of 266 nm, using a recently developed particle separation device. Various particle fractions were separated from the aerosol entering the ICP. The decrease in signal intensity is not proportional to the decrease in volume, indicating that particles above 150 nm in diameter are not completely ionised in the ICP. Due to the limited removal range of the particle separation device, which cannot remove particles smaller than 150 nm, single hole ablations were used to determine the lower vaporisation limit. This is based on measurements showing that larger particles occur dominantly during the first 100 laser pulses only. After this period, the ratio of ICP-MS counts and total particle volume was found to be constant while most of the particles are smaller than 90 nm, indicating complete vaporisation and ionisation of these particles.To describe the influence of different plasma forward powers on the vaporisation limit, the range 1000–1600 W was studied. Results indicate that optimum vaporisation and ionisation occurs at 1300 W. However, an increase of the particle ionisation limit towards larger particles was not observed within the accuracy of this study using the full range of parameters available for optimisation on commonly used ICP-MS instruments. 相似文献
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The objective of this study was to examine some fundamental factors involved in the design and construction of the anode magnetron dc glow discharge processes as well as its performance in plasma cleaning and polymerization. Those advantages of anode magnetron include the capability of the magnetron to operate at low pressure, as well as decreasing the thickness of cathode dark space, i.e., the negative glow which contains a higher concentration of ions and active species was more closely to the cathode surface, which makes the plasma surface cleaning and polymerization an effective and uniform processes. The deposition rate at a given discharge power is increased by the presence of anode magnetrons, and is also much higher relative to rf and af. The refractive index of dc plasma film at a given polymer thickness (such as TMS, 70 nm, RI: 2.4) is higher than rf, af, and cascade arc plasma (RI: 1.6–1.7). 相似文献
64.
《Arabian Journal of Chemistry》2020,13(2):4082-4091
In present study, an investigation was carried out to develop and validate an analytical method for the selective extraction and determination of griseofulvin (GSF) from plasma samples. For this purpose, a rational approach was made to synthesize and characterize the surface molecularly imprinted polymers (SMIPs). The SMIPs were utilized as solid phase extraction (SPE) sorbents. The SMIPs were prepared by using GSF as template molecule on the surface of modified silica particles through a non-covalent technique. The particles demonstrated high adsorption capacity (119.1 µg/mL), fast adsorption equilibrium time (30 min) and good recognition selectivity for the template drug. The scanning electron microscopy and infrared spectroscopy were used to explain the structural and morphological characteristics of the SMIPs and surface non-imprinted polymers. The SPE method was combined with HPLC for plasma analysis. The method validation results demonstrated that the established method possessed good linearity for GSF ranging from 0.1 to 50 µg/mL (R2 = 0.997). The limit of detection for this method was 0.02 µg/mL for rat plasma samples. The recoveries of GSF from spiked plasma samples were (90.7–97.7%) and relative standard deviations were (0.9–4.5%). Moreover, the SMIPs as selective SPE sorbent can be reused more than 8 times which is a clear advantage over commercial SPE sorbents. Finally, the usefulness of the proposed strategy was assessed by extraction and detection of GSF in real rat plasma samples. 相似文献
65.
在Angara-5-1联合实验中,利用条纹像机和光纤阵列实现时间分辨和1维空间分辨,得到了丝阵条纹像,观察到丝阵负载箍缩区X光辐射的1维轴向空间分布信息随时间的演化过程,考察了内爆的同步性和均匀性。通过对比不同结构负载内爆等离子体X光1维时空分布信息,发现由于内层等离子体对磁流体瑞利-泰勒不稳定性的抑制作用,(40+20)根双层钨丝阵比60根单层钨丝阵的内爆轴向同步性好,产生的X光辐射功率高;由于负载存在弯曲、断丝、扭曲等现象,(60+30)根双层钨丝阵比90根单层钨丝阵的轴向同步优势不明显;轴向同步性好与辐射功率高之间存在相关性;辐射波形前沿较快时,X光功率较高。 相似文献
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Stephanie Hansen G.S.J. Armstrong S. Bastiani-Ceccotti C. Bowen H.-K. Chung J.P. Colgan F. de Dortan C.J. Fontes F. Gilleron J.-R. Marquès R. Piron O. Peyrusse M. Poirier Yu. Ralchenko A. Sasaki E. Stambulchik F. Thais 《High Energy Density Physics》2013,9(3):523-527
Collisional-radiative atomic models are widely used to help diagnose experimental plasma conditions through fitting and interpreting measured spectra. Here we present the results of a code comparison in which a variety of models determined plasma temperatures and densities by finding the best fit to an experimental L-shell Kr spectrum from a well characterized, but not benchmarked, laser plasma. While variations in diagnostic strategies and qualities of fit were significant, the results generally confirmed the typically quoted uncertainties for such diagnostics of ±20% in electron temperature and factors of about two in density. The comparison also highlighted some model features important for spectroscopic diagnostics: fine structure was required to match line positions and relative intensities within each charge state and for density diagnostics based on emission from metastable states; an extensive configuration set was required to fit the wings of satellite features and to reliably diagnose the temperature through the inferred charge state distribution; and the inclusion of self-consistent opacity effects was an important factor in the quality of the fit. 相似文献
69.
The goal of the present experimental study is to investigate the ability of surface DBD plasma actuators to delay flow separation along the suction side of a NACA0015 airfoil. Three single surface DBD actuators that can operate separately are mounted on the suction side of the profile, at 18%, 27% and 37% of the chord length. The boundary layer is transitioned by a tripper to be sure that the flow control is not due to the laminar-to-turbulent transition. The angle of attack is equal to 11.5° and the free-stream velocity to U0 = 40 m/s, resulting in a chord-based Reynolds number of Rec = 1.33 × 106. The flow is studied with a high-resolution PIV system. In such conditions, the baseline flow separation occurs at 50% of chord. Then, the different single DBD have been switched on separately, in order to investigate the actuator location effect. One highlights that the DBD located at xc/c = 18% is more effective than the two others ones, with a separation delay up to 64% of chord. When the three DBDs operate simultaneously, the separation point moves progressively toward the trailing edge when the high voltage is increased, up to 76% of chord at 20 kV. Finally, the effect of the actuation frequency on the control authority has been investigated, by varying the value of the operating frequency and by burst-modulation. For frequencies equal to 50 Hz and 500 Hz (reduced frequency F+ = 0.31 and 3.1), the separation has been delayed at 76 and 80% of chord, respectively. 相似文献
70.
The stabilization of partially-premixed jet flames in the presence of high potential electric fields
Numerous research efforts have focused on flame stabilization and emissions. Based on initial experiments, specific mechanisms resulting from DC electric fields were chosen to be investigated, namely the chemical, thermal, and ionization mechanisms. Numerical simulations were performed on premixed propane-ozone-air flames to characterize ozone effects on flame speed resulting from the formation of ozone in high potential electric fields. These results were compared against partially premixed flame experiments to observe the dominant influences within leading edge stabilization within high potential electric fields. It was found that the electromagnetic or ionization influences, serve as the dominant effect on the combustion zone. 相似文献