【作者】 袁洪林；

【导师】 高山；

【作者基本信息】 中国地质大学 ， 岩石圈地球化学， 2002， 博士

【摘要】 本文对溶液雾化和激光剥蚀ICP-MS在地球科学中的应用进行探讨。主要开展了如下三方面研究:利用溶液雾化ICP-MS（SN-ICPMS）对实验室本底的定量监测、仪器参数的优化,利用自行研制的溶样弹,进行地质样品的分析测试;利用193nm准分子激光剥蚀ICP-MS（ELA-ICPMS）探索了进行岩石样品部分主、微量元素快速分析的仪器条件,并开展了长达19个月的USGS和NIST国际标准样品的测试工作;进行单颗粒锆石的微区定年研究等。 1.SN-ICPMS进行岩石样品的微量元素分析 利用ICP-MS检出限较低的功能对净化实验室的制水、制酸过程进行了监测。通过对自来水、蒸馏水、去离子水及超纯水的监测,发现Ag污染来自盛装超纯水（18MΩ）的塑料瓶;超纯HNO₃中的Sb（121和123amu两个相应的质量峰）和I（127amu）由于易挥发,故采用亚沸蒸馏并不能有效地除去;HF的高Sb信号并不是HF本身受Sb污染,而是其对雾室、雾化器、炬管等的侵蚀引起;HClO₄中高的85amu信号是由同量异位素或多原子离子的干扰而造成,而不是⁸⁵Rb受到污染。 对仪器的参数采用正交法(正交表是L₆₄（8⁹×3¹×2¹）)进行优化,发现离子透镜Lens 2和Lens3的电压水平（电压水平指正交表中的水平）应该相近;离子透镜Lens 4的电压水平应该比Lens2和Lens 3的都低一些;Collector的电压水平应该与Aperture的接近,并且都比Lens 4的电压水平要大;Pole Bias的电压水平应该比Aperture和Collector的电压水平都要小。Sampling Depth,即采样深度,应该在6mm左右;辅助气的流量应该接近于1.0L/min;RF的功率应该在1350w附近;Aperture的电压应该在-72v,即水平3左右;Collector的电压应该大于-9v,即水平3;Aperture、Pole Bias和Extractor的电压水平呈“∨”时,信号灵敏度增加,而当呈“∧”时信号灵敏度则下降。另外,影响峰中心曲线的主要因素是雾化气流量,Extractor、Pole Bias和Lens 4的电压。在离子通道的各个电压参数中Lens 3,Lens 4,Pole bias和Extractor的电压是主要控制峰中心曲线形状的参数。高的Lens 3电压和低的Lens 4电压会提高重质量数元素的灵敏度;低Pole bias电压和高的Extractor电压也有相同的效果。 自行设计并研制了适用于地质样品全岩分析的溶样弹,并实验出对普通地质样品溶解的酸组合,即1.5mL硝酸、1.5mL氢氟酸和0.02mL高氯酸,温度195℃,时间36小时。该溶样方法对部分不同岩类国际标样BHVO-1（玄武岩）,AGV-1（安山岩）,G-2（花岗岩）等进行了长期测定,结果较好。 2.ELA-ICPMS进行地质样品微区部分主、微量元素分析 实验研究结果表明,对于单矿物的微区微量元素分析,ELA-ICPMS的参数优化方案为:（1）载气流量选取0.55L/min;（2）激光频率增大时激光剥蚀出的样品量增多,信号比较平稳,但是剥深速率加快,元素间的分馏效应增大,综合考虑后一般选用10Hz;（3）激光能量的增大提高了剥蚀能力,即激光剥蚀出的样品量增多,信号灵敏度提高,一般选取ComPlex102激光器的最大高压30Kv对应的能量170～210mJ。若低于该能量,需要重新更换激光工作气体。对于易碎更多还原

【Abstract】 This work describes the applications of solution nebulization and laser ablation inductively coupled plasma mass spectrometry in geosciences. Solution Nebulization Inductively Coupled Plasma Mass Spectrometry （SN-ICPMS） is used widely nowadays. It was used to monitor the background of clean labs and helped to find the source of impurities in ultra pure water and ultra pure acids in this study. Parameter optimization of a POEMS III ICP-MS was discussed in this work. The author designed and manufactured an Acid Digestion Teflon Bomb （ADTB） in order to digest geological samples. International reference materials were analyzed with the ADTB with satisfactory results.Excimer Laser Ablation Inductively Coupled Plasma Mass Spectrometry （ELA-ICPMS） is a newly developed strategy for direct solid sample micro analysis and zircon dating. In this paper an extensive study has been done and optimum instrumental parameters were obtained. Analysis of USGS rock glass standards BCR-2G, BHVO-2G and BIR-1G and NIST synthetic silicate glasses NIST 610, NIST 612 and NIST 614 show both relative standard deviations and relative deviation of the obtained values from recommended values better than 10%. In-situ single-grain zircon U-Pb dating was carried out by the ELA-ICPMS technique.1 Analysis of trace Elements of geological samples by SN-ICPMSImpurities in ultra pure water and acids were analyzed by SN-ICPMS. With careful analysis of tap water, distilled water, deionized water and ultra pure water, the Ag impurity is found to be derived from polyethene bottle, which should be cleaned with care. Antimony （121 and 123 amu） and iodine （127 amu） of ultra pure HNO₃ is still significant after sub-boiling distillation. They were difficult to be consumed for their low boiling points. Significant antimony （121 amu and 123 amu） in ultra pure HF was probably attributed to the corrosion of the glass torch and spray chamber by hydrofluoric acid, because the intensities of these masses in the 5% hydrofluoric acid were only twice of the intensities in the 0.5% solution. Signal at 85 amu in ultra pure HClO₄ should be emphasized since no corresponding signal is found at 87 amu. Because Rb has two isotopes with natural abundance for ⁸⁵Rb and ⁸⁷Rb being 72.15% and 27.85%, respectively, isobaric or polyatomic interference must exist at 85 amu.The orthogonal method can be used to predict the optimum instrumental conditions and to guide the optimizing operations. This simplifies the ICP-MS optimization. In general, the final optimum parameter combination used in an analysis can be obtained with fine adjustments of the preferred parameters derived from the orthogonal experiment. This method can also be used to study the relationship between the parameter settings and the signal intensity deflection to improve the analysis of elements with a limited mass range. Significant results are listed as follows: （1） the Lens 2 and Lens 3 voltage levels should be similar; （2） the Lens 4 voltage level should be lower than the Lens 2 and Lens 3 voltage levels; （3） the collector voltage level should be higher than the Lens 4 voltage level and close tothe aperture voltage level; and （4） the pole bias voltage level should be lower than the aperture and extractor voltage levels. It is also suggested that （1） the sampling depth should be set at about 6 mm; （2） the auxiliary gas-flow rate should be close to 1.0 L/min and the RF power to 1350 W; （3） the collector voltage should be higher than -9 V （Level 3）; （4） the aperture voltage should be around -72 V （Level 3）; and （5） the aperture, pole bias and extractor voltages exhibit either a "v" or a ’Vshape, which corresponds to an increased or decreased sensitivity. Following rule can be applied to obtain different signal intensity deflection: the higher is the nebulizer gas-flow rate, the higher is the sensitivity of the light elements, and vice versa; higher Lens 3 and lower Lens 4 voltages leads to a higher signal intensity over a higher mass range. A combined lower pole bias and higher extractor voltages have a similar effect.The author made a specially designed Teflon bomb to digest geological samples in a mixture of 1.5 mL HNO3, 1.5 mL HC1 and 0.02 mL HC1O4. The obtained analysis conducted over a period 19 months for international rock reference materials show good agreement with recommended values.2) In situ micro analysis by ELA-ICPMSELA-ICPMS optimum conditions are studied. Main conclusions are the following: （Dthe carrier gas flow rate is set at 0.55 0.77 L/min; （2） compromised laser frequency is set at 10 Hz; Q） laser energy is set at maximum energy of Complexl02. The working gas of the laser cell should be refilled when the energy is below 150 mJ （10 Hz）; <3> the compromise laser ablation spot size is 60 um. ? the integration intervals of laser ablation signal is 30 60 s normally. ? Si, Al, Ti, and Ca are usually selected as internal standard elements. Si is used to calibrate Li, Be, Na, P, V, Mn, Co, Ni, Cu, Zn, Rb, Sr, Cs, and Ba. Al, Ti and Mg are used to calibrate La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, Cr, Ga, Y, Zr, Hf, Ta, Pb, Th and U. Ca is used to calibrate Na, Mg, Al, Si, P, Sc, Ti, Co, Cu, Sr, Nb, and rare earth elements. Q) Time of Quadruopole Settling Time and Dwell Time are set at 10 ms and 0.6 ms, respectively. ? the Sweeps/reading is set at 2 with consideration of micro information of geological samples and stability of signals.Analysis of several USGS and NIST reference glasses with ELA-ICPMS for 19 months show that the ELA-ICPMS can provide results with precision and accuracy comparable to SN-ICPMS.3. Single grain zircon dating by ELA-ICPMSInstrumental conditions were obtained after U-Pb fractionation study with NIST, USGS standard glasses and Harvard standard zircon 91500. （1） laser frequency is set at 8 Hz; （2） spot size is set at 60 Um; （3） Quadrupole Settling Time and Dwell Time are set at 12 ms and 0.6 ms, respectively; （4） Sweeps/reading is set at 3. Other conditions are the same as ELA-ICPMS analysis of trace elements.The Harvard Univeristy standard zircon 91500 and ANU standard zircon TEM were analyzed under the above optimum conditions. TIMS reference results on 91500 are 238U/206Pb=5.5813, 207Pb/206Pb=0.07488, 2O7Pb/235U=1.8502, 206Pb/238U=0.1792, and U-Pb age=1065.4 ± 0.6 Ma. Corresponding results from this study are 5.600, 0.0752, 1.85 and 0.179, Tera-Wasserburg Concordia age 1064+12/-9.7Ma （MSWD=0.86）, and Conventional Concordia age 1064 +14/-9.9 Ma （MSWD=0.82）. For TEM, SHRIMP reference results are 238U/206Pb=14.67998, 207Pb/2O6Pb=0.05582, 207Pb/235U=0.52425,206Pb/238U=0.06812 and U-Pb age= 417 + 20 Ma. These compare to the results ofthe present study: 14.784, 0.055, 0.51 and 0.068, Tera-Wasserburg concordia age 423+52A48 Ma （MSWD=0.44） and conventional concordia age 421 ± 24 Ma （MSWD=0.48）. Therefore our ELA-ICPMS results on both zircons show excellent agreement with TIMS and SHRIPM values.更多还原