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从随机到取向--分子转动动力学的超快调控 总被引:1,自引:0,他引:1
分子取向物理是研究如何操控分子空间排列方向以及如何制备具有特定方向的分子。近十多年来,分子取向物理学取得巨大进展,人们通过各种技术对分子取向物理进行研究,使人们对分子取向的认识达到一个全新的高度。文章首先介绍了分子的量子态及其分布,转动量子态选择方法和分子的转动动力学,然后概述通过制备和调控转动态的相干布居来控制分子取向的方法。实验和理论表明,分子的不同转动态在相同激光条件作用下产生的转动波包不一样,从而导致分子的准直和取向程度随时间演化完全不一样。通过选择合适的转动量子态能够很好地提高分子取向程度。取向分子作为相互作用靶,为原子分子动力学、精密测量物理、立体化学反应和表面碰撞过程等提供了更加丰富多彩的研究内容。 相似文献
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Yuzhuo Wang Zejian Huang You Jiang Xingchuang Xiong Yulin Deng Xiang Fang Wei Xu 《Journal of mass spectrometry : JMS》2013,48(8):937-944
A theoretical method, the harmonic balance method, was introduced to study the coupling effects of hexapole and octopole fields on ion motion in a quadrupole ion trap. Ion motion characteristics, such as ion motion center displacement, ion secular frequency shift, nonlinear resonance curve and buffer gas damping effects, have been studied with the presence of both hexapole and octopole fields. It is found that hexapole fields have bigger impacts on ion motion center displacement, while octopole fields dominate ion secular frequency shift. Furthermore, the nonlinear features originated from hexapole and octopole fields could enhance or cancel each other, which provide us more space in a practical ion trap design process. As an example, an ion trap with improved performance was designed using a specific combination of hexapole and octopole fields. In this ion trap, a hexapole field was used to achieve efficient ion directional ejection, while an octopole field was added to correct the chemical mass shift and resolution degradation introduced by the hexapole field. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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阐述求解极性分子转动态选择及取向静电六极装置中势能分布、电场分布的数值计算方法.为了获得电场分布公式,需通过数值迭代求解势能满足的Laplace方程,获取数值分布点,通过数值分布点,由待定系数的多级展开势能解析表达式进行最小二乘拟合获得势能分布公式,由势能对空间向量的微分获得电场分布.分子在六极电场中的运行轨迹采用经典Newton方程描述,并通过四阶龙格-库塔方法(Four Order Runge-Kutta Method)实现数值求解,其中能量处理采用量子力学方法.应用此方法给出静电六极装置的电场分布公式,运用获得的电场分布公式计算和讨论电场对极性分子N2O的静电六极转动态选择、取向所带来的影响. 相似文献
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The application of a hexapole collision cell in quadrupole based inductively coupled plasma mass spectrometry (HEX-ICP-QMS)
was studied systematically in order to characterize the performance of this approach for multielement analysis. Additionally,
the performance of different solution introduction systems was studied for use with HEX-ICP-QMS (Platform, Micromass Ltd.,
Manchester, UK) and the developed methods were applied in the multielement analysis of biological tissue. A significant improvement
in detection limits was achieved for ions affected by interferences with argon ions and argon-based molecular ions due to
the removal of Ar+ and ArX+ ions (X = H, C, N, O, Ar) as well as for heavy elements (m > 100 u) due to better ion transmission through the hexapole ion
guide. Metal oxide ion formation was reduced by up to ten times by the application of hexapole bias potential. Accuracy of
the HEX-ICP-QMS measurements was assessed by analyzing standard reference material SRM 1566a Oyster Tissue and comparison
with neutron activation analysis. Good agreement of measured trace element concentrations with certified values was found
for most elements.
Received December 7, 2000. Revision April 3, 2001. 相似文献
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运用王函数(Wang Function)组合构成转动波函数推导了不对称陀螺分子转动能及其在外电场作用下的Stark能量的表达式,并将其应用到六极静电场态选择理论计算中.使用类似简并能级的计算方法讨论了彼此接近能级情况下分子转动态选择情况,获得了对(CH3)2O、O3、SO2分子实现获得具有高各项异性取向的分子束的优化条件. 相似文献
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Determination of copper using inductively coupled plasma mass spectrometry (ICP-MS) suffers from polyatomic overlays originating
from Na+ and Mg2+ matrix elements due to the formation of 40Ar23Na+ and 40Ar25Mg+ in the mass-to-charge ratios of 63 and 65, respectively. The collision/reaction cell technology belongs to the most modern
methods used to overcome polyatomic interferences. Gas-filled collision/reaction cell can cause an additional mass bias effect
influencing analytical precision of the method. In this study, the additional mass bias effect of the hexapole collision/reaction
cell ICP-MS was studied on an example of n(65Cu)/n(63Cu) isotope ratio. As a result, a method for suppressing polyatomic interference on the mass-to-charge ratio of 63 and 65
was introduced and additional mass bias of the collision/reaction cell was lowered to an acceptable level. 相似文献
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建立了直接稀释法测定海水中痕量金属元素Cr,Cu,Zn,Cd,Pb的方法。样品经稀释10倍后,使用基体匹配及内标校正,采用六极杆碰撞反应池–电感耦合等离子体质谱仪直接测定稀释后海水样品中的5种元素Cr,Cu,Zn,Cd,Pb。各元素在0.0~100μg/L范围内均呈现良好的线性关系,线性相关系数(r~2)均大于0.999 0,方法检出限为0.004~0.209μg/L。测定结果的相对标准偏差为2.4%~4.4%(n=6),加标回收率为92%~113%。该方法简单快捷,适用于近岸海水中痕量元素Cr,Cu,Zn,Cd,Pb的分析。 相似文献