In the present work, we have studied the temporal evolution of aluminum alloy plasma produced by the fundamental (1064 nm) of a Q-switched Nd:YAG laser by placing the target material in air at atmospheric pressure. Th...In the present work, we have studied the temporal evolution of aluminum alloy plasma produced by the fundamental (1064 nm) of a Q-switched Nd:YAG laser by placing the target material in air at atmospheric pressure. The four Al I-neutral lines at 308.21, 309.27, 394.40 and 369.15 nm as well as Al II-ionic lines at 281.61, 385.64 and 466.30 nm are used for the determination of the electron temperature Te using Saha-Boltzmann plot method. The neutral aluminum lines were found to suffer from optical thickness which manifested itself on the form of scattered points around the Saha-Boltzmann line. The isolated optically thin hydrogen Hα-line at 656.27 nm appeared in the spectra under the same experimental conditions was used to correct the Al I-lines which contained some optical thickness. The measurements were repeated at different delay times ranging from 1 to 5 μs. The comparison between the deduced electron temperatures from aluminum neutral lines before correction against the effect self-absorption to that after correction revealed a precise value in temperature. The results sure that, in case of the presence of self-absorption effect the temperature varies from (1.4067 - 1.2548 eV) as the delay time is varied from 0 to 5 μs. Whereas, in the case of repairing against the effect, it varies from (1.2826 - 0.8961 eV) for the same delay time variation.展开更多
This work reports that the intensity ratio of spectral lines having similar self-absorption characteristics during laser induced breakdown spectroscopy(LIBS) analysis can become nearly constant over a wide range of ir...This work reports that the intensity ratio of spectral lines having similar self-absorption characteristics during laser induced breakdown spectroscopy(LIBS) analysis can become nearly constant over a wide range of irradiation conditions if the intensities are integrated over a sufficiently long time. It is shown that the plasma temperature and intensity ratio of these spectral lines have temporal similarity. The spectral lines with similar self-absorption properties may be selected to improve the accuracy and consistency of LIBS analysis results under an environment with fluctuating measurement conditions.展开更多
Laser-induced breakdown spectroscopy(LIBS) is a promising analytical spectroscopy technology based on spectroscopic analysis of the radiation emitted by laser-produced plasma.However, for quantitative analysis by LIBS...Laser-induced breakdown spectroscopy(LIBS) is a promising analytical spectroscopy technology based on spectroscopic analysis of the radiation emitted by laser-produced plasma.However, for quantitative analysis by LIBS, the so-called self-absorption effects on the spectral lines, which affect plasma characteristics, emission line shapes, calibration curves, etc, can no longer be neglected. Hence, understanding and determining the self-absorption effects are of utmost importance to LIBS research. The purpose of this review is to provide a global overview of self-absorption in LIBS on the issues of experimental observations and adverse effects,physical mechanisms, correction or elimination approaches, and utilizations in the past century.We believe that better understanding and effective solving the self-absorption effect will further enhance the development and maturity of LIBS.展开更多
Laser-induced breakdown spectroscopy （LIBS） has been used to detect atomic species in various enviromnents. The quantitative analysis （C, H, O, N and S） of representative coal samples are being carried out with LI...Laser-induced breakdown spectroscopy （LIBS） has been used to detect atomic species in various enviromnents. The quantitative analysis （C, H, O, N and S） of representative coal samples are being carried out with LIBS, and the effects of particle size are analyzed. A powerful pulse Nd：YAG laser is focused on the coal sample at atmosphere pressure, and the emission spectra from laser-induced plasmas are measured by time-resolved spectroscopy, and the intensity of analyzed spectral lines is obtained through observing the laser plasma with a delay time of 0.4 #s. The experimental results show that the slope of calibration curve is nearly 1 when the concentration of the analyzed element is relatively low, and the slope of curve is nearly 0.5 when the concentration of C is higher than other elements. In addition, using the calibration-free model without self-absorption effect, the results show that the decreasing of particle size leads to an increase of the plasma temperature.展开更多
A non-depletion floating layer silicon-on-insulator （NFL SOI） lateral double-diffused metal–oxide–semiconductor （LDMOS） is proposed and the NFL-assisted modulated field （NFLAMF） principle is investigated in th...A non-depletion floating layer silicon-on-insulator （NFL SOI） lateral double-diffused metal–oxide–semiconductor （LDMOS） is proposed and the NFL-assisted modulated field （NFLAMF） principle is investigated in this paper. Based on this principle, the floating layer can pin the potential for modulating bulk field. In particular, the accumulated high concentration of holes at the bottom of the NFL can efficiently shield the electric field of the SOI layer and enhance the dielectric field in the buried oxide layer （BOX）. At variation of back-gate bias, the shielding charges of NFL can also eliminate back-gate effects. The simulated results indicate that the breakdown voltage （BV） is increased from 315 V to 558 V compared to the conventional reduced surface field （RESURF） SOI （CSOI） LDMOS, yielding a 77% improvement. Furthermore, due to the field shielding effect of the NFL, the device can maintain the same breakdown voltage of 558 V with a thinner BOX to resolve the thermal problem in an SOI device.展开更多
The complex nature of laser-material interaction causes non-stoichiometric ablation of alloy samples.This is attributed to matrix effect, which reduces analyzing capability. To address this issue, the analytical perfo...The complex nature of laser-material interaction causes non-stoichiometric ablation of alloy samples.This is attributed to matrix effect, which reduces analyzing capability. To address this issue, the analytical performance of three different normalization methods, namely normalization with background, internal normalization and three point smoothing techniques at different parameter settings is studied for quantification of Ag and Zn by Laser induced breakdown spectroscopy(LIBS).The LIBS spectra of five known concentration of silver zinc binary composites have been investigated at various laser irradiances(LIs). Calibration curves for both Ag(I) line(4d^(10)5s^2S_(1/2)→4d^(10)5p^2P_(1/2) at 338.28 nm) and Zn(I) line(4s5s^3S_1→4s4p^3P_2 at 481.053 nm) have been determined at LI of 5.86?×?10^(10)W cm^(-2). Slopes of these calibration curves provide the valuation of matrix effect in the Ag–Zn composites. With careful sample preparation and normalization after smoothing at optimum parameter setting(OPS), the minimization of sample matrix effect has been successfully achieved. A good linearity has been obtained in Ag and Zn calibration curve at OPS when normalized the whole area of spectrum after smoothing and the obtained coefficients of determination values were R^2?=?0.995 and 0.998 closer to 1. The results of matrix effect have been further verified by analysis of plasma parameters. Both plasma parameters showed no change with varying concentration at OPS. However, at high concentration of Ag, the observed significant changes in both plasma parameters at common parameter setting PS-1 and PS-2 were the gesture of matrix effect. In our case, the better analytical results were obtained at smoothing function with optimized parameter setting that indicates it is more efficient than normalization with background and internal normalization method.展开更多
This paper presents a novel high-voltage lateral double diffused metal-oxide semiconductor （LDMOS） with self- adaptive interface charge （SAC） layer and its physical model of the vertical interface electric field. ...This paper presents a novel high-voltage lateral double diffused metal-oxide semiconductor （LDMOS） with self- adaptive interface charge （SAC） layer and its physical model of the vertical interface electric field. The SAC can be self-adaptive to collect high concentration dynamic inversion holes, which effectively enhance the electric field of dielectric buried layer （EI） and increase breakdown voltage （BV）. The BV and EI of SAC LDMOS increase to 612 V and 600 V/tim from 204 V and 90.7 V/ttm of the conventional silicon-on-insulator, respectively. Moreover, enhancement factors of r/which present the enhanced ability of interface charge on EI are defined and analysed.展开更多
金属化聚丙烯薄膜电容器(metallized polypropylene film capacitors, MPPFC)在充电条件下的自愈击穿可能造成电极和介质膜的永久性损伤,导致其电容减少和介电损耗增加。基于此,本文研究了MPPFC充电过程中的宏观特征量—自愈电压、自愈...金属化聚丙烯薄膜电容器(metallized polypropylene film capacitors, MPPFC)在充电条件下的自愈击穿可能造成电极和介质膜的永久性损伤,导致其电容减少和介电损耗增加。基于此,本文研究了MPPFC充电过程中的宏观特征量—自愈电压、自愈能量、电极损失面积等的演变规律并结合仿真分析了介质膜表面微观结构的变化特性。结果显示,自愈能量随自愈电压增加呈幂函数增长,与电极损失面积正相关,受电弧放电的影响,高压电极损失面积大于地电极且形状较地电极规则,其边界分形维数平均值(1.525)小于地电极(1.665)。此外,电极孔洞缺口轴向边缘的电流密度高于切向边缘,致使金属化聚丙烯薄膜自愈击穿过程中金属化电极轴向损伤高于切向。了解这些特性对全面揭示多场耦合复杂工况下MPPFC物性演化规律具有重要意义。展开更多
文摘In the present work, we have studied the temporal evolution of aluminum alloy plasma produced by the fundamental (1064 nm) of a Q-switched Nd:YAG laser by placing the target material in air at atmospheric pressure. The four Al I-neutral lines at 308.21, 309.27, 394.40 and 369.15 nm as well as Al II-ionic lines at 281.61, 385.64 and 466.30 nm are used for the determination of the electron temperature Te using Saha-Boltzmann plot method. The neutral aluminum lines were found to suffer from optical thickness which manifested itself on the form of scattered points around the Saha-Boltzmann line. The isolated optically thin hydrogen Hα-line at 656.27 nm appeared in the spectra under the same experimental conditions was used to correct the Al I-lines which contained some optical thickness. The measurements were repeated at different delay times ranging from 1 to 5 μs. The comparison between the deduced electron temperatures from aluminum neutral lines before correction against the effect self-absorption to that after correction revealed a precise value in temperature. The results sure that, in case of the presence of self-absorption effect the temperature varies from (1.4067 - 1.2548 eV) as the delay time is varied from 0 to 5 μs. Whereas, in the case of repairing against the effect, it varies from (1.2826 - 0.8961 eV) for the same delay time variation.
基金supported by the R&D Center for Valuable Recycling (Global-Top R&BD Program) of the Ministry of Environment (Project No. 2016002250003)
文摘This work reports that the intensity ratio of spectral lines having similar self-absorption characteristics during laser induced breakdown spectroscopy(LIBS) analysis can become nearly constant over a wide range of irradiation conditions if the intensities are integrated over a sufficiently long time. It is shown that the plasma temperature and intensity ratio of these spectral lines have temporal similarity. The spectral lines with similar self-absorption properties may be selected to improve the accuracy and consistency of LIBS analysis results under an environment with fluctuating measurement conditions.
基金supported by National Key R&D Program of China (2017YFA0304203)Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China (IRT13076)+1 种基金National Natural Science Foundation of China (NSFC) (Nos. 61475093, 61875108, 61775125)Major Special Science and Technology Projects in Shanxi Province (MD2016-01)
文摘Laser-induced breakdown spectroscopy(LIBS) is a promising analytical spectroscopy technology based on spectroscopic analysis of the radiation emitted by laser-produced plasma.However, for quantitative analysis by LIBS, the so-called self-absorption effects on the spectral lines, which affect plasma characteristics, emission line shapes, calibration curves, etc, can no longer be neglected. Hence, understanding and determining the self-absorption effects are of utmost importance to LIBS research. The purpose of this review is to provide a global overview of self-absorption in LIBS on the issues of experimental observations and adverse effects,physical mechanisms, correction or elimination approaches, and utilizations in the past century.We believe that better understanding and effective solving the self-absorption effect will further enhance the development and maturity of LIBS.
基金The project supported by Specialized Research Fund for the Doctoral Program of Higher Education (No. 20020487013) and bythe Key Program for International Cooperation of Science and Technology of China (No. 2001 CB711203)
文摘Laser-induced breakdown spectroscopy （LIBS） has been used to detect atomic species in various enviromnents. The quantitative analysis （C, H, O, N and S） of representative coal samples are being carried out with LIBS, and the effects of particle size are analyzed. A powerful pulse Nd：YAG laser is focused on the coal sample at atmosphere pressure, and the emission spectra from laser-induced plasmas are measured by time-resolved spectroscopy, and the intensity of analyzed spectral lines is obtained through observing the laser plasma with a delay time of 0.4 #s. The experimental results show that the slope of calibration curve is nearly 1 when the concentration of the analyzed element is relatively low, and the slope of curve is nearly 0.5 when the concentration of C is higher than other elements. In addition, using the calibration-free model without self-absorption effect, the results show that the decreasing of particle size leads to an increase of the plasma temperature.
文摘A non-depletion floating layer silicon-on-insulator （NFL SOI） lateral double-diffused metal–oxide–semiconductor （LDMOS） is proposed and the NFL-assisted modulated field （NFLAMF） principle is investigated in this paper. Based on this principle, the floating layer can pin the potential for modulating bulk field. In particular, the accumulated high concentration of holes at the bottom of the NFL can efficiently shield the electric field of the SOI layer and enhance the dielectric field in the buried oxide layer （BOX）. At variation of back-gate bias, the shielding charges of NFL can also eliminate back-gate effects. The simulated results indicate that the breakdown voltage （BV） is increased from 315 V to 558 V compared to the conventional reduced surface field （RESURF） SOI （CSOI） LDMOS, yielding a 77% improvement. Furthermore, due to the field shielding effect of the NFL, the device can maintain the same breakdown voltage of 558 V with a thinner BOX to resolve the thermal problem in an SOI device.
基金supported by National Natural Science Foundation of China (Nos. 11475039, 11705020, 11605023)Liaoning Provincial Natural Science Foundation of China (No. 20170540153)
文摘The complex nature of laser-material interaction causes non-stoichiometric ablation of alloy samples.This is attributed to matrix effect, which reduces analyzing capability. To address this issue, the analytical performance of three different normalization methods, namely normalization with background, internal normalization and three point smoothing techniques at different parameter settings is studied for quantification of Ag and Zn by Laser induced breakdown spectroscopy(LIBS).The LIBS spectra of five known concentration of silver zinc binary composites have been investigated at various laser irradiances(LIs). Calibration curves for both Ag(I) line(4d^(10)5s^2S_(1/2)→4d^(10)5p^2P_(1/2) at 338.28 nm) and Zn(I) line(4s5s^3S_1→4s4p^3P_2 at 481.053 nm) have been determined at LI of 5.86?×?10^(10)W cm^(-2). Slopes of these calibration curves provide the valuation of matrix effect in the Ag–Zn composites. With careful sample preparation and normalization after smoothing at optimum parameter setting(OPS), the minimization of sample matrix effect has been successfully achieved. A good linearity has been obtained in Ag and Zn calibration curve at OPS when normalized the whole area of spectrum after smoothing and the obtained coefficients of determination values were R^2?=?0.995 and 0.998 closer to 1. The results of matrix effect have been further verified by analysis of plasma parameters. Both plasma parameters showed no change with varying concentration at OPS. However, at high concentration of Ag, the observed significant changes in both plasma parameters at common parameter setting PS-1 and PS-2 were the gesture of matrix effect. In our case, the better analytical results were obtained at smoothing function with optimized parameter setting that indicates it is more efficient than normalization with background and internal normalization method.
基金Projects supported by the National Natural Science Foundation of China （Grant Nos. 60806025 and 60976060）, the National Laboratory of Analog Integrated Circuit （Grant No. 9140C0903070904）, and the Youth Teacher Foundation of the University of Electroniq Science and Technology of China （Grant No. ix0721）.
文摘This paper presents a novel high-voltage lateral double diffused metal-oxide semiconductor （LDMOS） with self- adaptive interface charge （SAC） layer and its physical model of the vertical interface electric field. The SAC can be self-adaptive to collect high concentration dynamic inversion holes, which effectively enhance the electric field of dielectric buried layer （EI） and increase breakdown voltage （BV）. The BV and EI of SAC LDMOS increase to 612 V and 600 V/tim from 204 V and 90.7 V/ttm of the conventional silicon-on-insulator, respectively. Moreover, enhancement factors of r/which present the enhanced ability of interface charge on EI are defined and analysed.
文摘金属化聚丙烯薄膜电容器(metallized polypropylene film capacitors, MPPFC)在充电条件下的自愈击穿可能造成电极和介质膜的永久性损伤,导致其电容减少和介电损耗增加。基于此,本文研究了MPPFC充电过程中的宏观特征量—自愈电压、自愈能量、电极损失面积等的演变规律并结合仿真分析了介质膜表面微观结构的变化特性。结果显示,自愈能量随自愈电压增加呈幂函数增长,与电极损失面积正相关,受电弧放电的影响,高压电极损失面积大于地电极且形状较地电极规则,其边界分形维数平均值(1.525)小于地电极(1.665)。此外,电极孔洞缺口轴向边缘的电流密度高于切向边缘,致使金属化聚丙烯薄膜自愈击穿过程中金属化电极轴向损伤高于切向。了解这些特性对全面揭示多场耦合复杂工况下MPPFC物性演化规律具有重要意义。
