Novel ion beams to enhance ionization in molecular secondary ion mass spectrometry

新型离子束增强分子二次离子质谱中的电离

• 批准号: EP/K01353X/1
• 负责人: John Vickerman
• 金额: $ 33.24万
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FK01353X%2F1
• 关键词: Novel; ion; beams; enhance; ionization

Secondary ion mass spectrometry (SIMS) is an analytical technique with unique potential to probe the chemistry of complex materials in 2D and 3D on the micron level without the need for chemical modification or tagging. Surface chemistry is desorbed (sputtered) using a focused high energy (keV) 'primary' ion beam and the ionised fraction is subjected to mass spectrometric analysis. Our research over the last several years has focused on developing the application of SIMS to the study of biological cells and tissue, although the outcomes are equally applicable to other complex systems such as organic electronic materials. Sensitivity is the central issue in mass spectrometry particularly in the imaging mode because the desire for increasing levels of spatial resolution means that the sample to be analysed gets smaller and smaller and there can never be enough ion yield. With EPSRC's support we have very successfully introduced and demonstrated the power of new primary ion beams for SIMS, first based on gold clusters and then on C60, that have greatly increased the ion yield of the large molecular species that are chemically significant. Despite these advances spatially resolved analysis below 1 micron is problematical because the current ionisation probability in organic SIMS (and indeed in other desorption mass spectrometries such as MALDI and DESI) is less than 10-5 in most cases. Related to this problem is the operation of the matrix effect. The secondary ion formation mechanism for compound A is influenced by the chemistry of the other molecules surrounding it in the emission zone. The ion yield of A may be enhanced, reduced or even entirely suppressed dependent on the identity of the surrounding molecules. This makes analysis uncertain and quantification very difficult. In the case of organic materials there is a considerable SIMS and MALDI literature that demonstrates the influence of the relative basicity of compound A compared to its molecular neighbours on the formation of the (A+H)+ species. Thus a significant contributor to the matrix effect is probably due to competition for protons in the ion emission zone. Thus in the case of organic analysis where the majority of molecular related ions are formed by proton transfer, greatly increasing the density of proton source molecules in the emission zone is expected to increase the M+H or M-H yields. In a collaboration with a small ion beam manufacturer, Ionoptika Ltd, this project will develop a water ion beam system capable of delivering a high density of either H3O+ or giant water cluster ions (H2O)nH+ (N=50 to 10000), that on impact with the sample surface will generate a high density of proton related species to enhance the secondary ion yield of (A+H)+ by at least a factor of 10, and is expected to have the added benefit of relieving the matrix effect. The project will be a mix of instrument development and water beam characterisation followed by research into its operation. The water beam system will be built refined and interfaced with an ion optical column developed previously for a giant argon cluster beam. The optimum operational conditions for the water beam will be researched and then using model compound systems the fundamentals of the degree and mechanism of proton assisted ion yield enhancement will be researched. This will then be followed by studies of multi-component model materials to investigate the influence of the water beam on the matrix effect and the improvement of quantitative analysis in imaging mass spectrometry. Time permitting we hope to carry out proof of principle studies into the beneficial effects of the water beam in MALDI MS.The successful outcome of this project will very significantly enhance the capabilities and wide uptake of SIMS, enabling molecular sub-micron analysis and imaging, greatly ameliorating the interference of the matrix effect and significantly improving quantitative measurements.

二次离子质谱（西姆斯）是一种分析技术，具有独特的潜力，可以在微米级上探测2D和3D复杂材料的化学性质，而无需进行化学修饰或标记。表面化学解吸（溅射）使用聚焦的高能量（keV）的“初级”离子束和电离部分进行质谱分析。在过去的几年里，我们的研究重点是开发西姆斯在生物细胞和组织研究中的应用，尽管其结果同样适用于其他复杂系统，如有机电子材料。灵敏度是质谱法中的中心问题，特别是在成像模式中，因为对增加空间分辨率水平的期望意味着待分析的样品变得越来越小，并且永远不会有足够的离子产率。在EPSRC的支持下，我们已经非常成功地引入并展示了用于西姆斯的新的初级离子束的功率，首先基于金簇，然后基于C60，这大大增加了具有化学意义的大分子物质的离子产率。尽管有这些进步，但低于1微米的空间分辨分析是有问题的，因为在有机西姆斯（以及实际上在其他解吸质谱法如MALDI和DESI）中的当前电离概率在大多数情况下小于10-5。与此相关的问题是矩阵效应的操作。化合物A的二次离子形成机制受到发射区中围绕它的其他分子的化学性质的影响。取决于周围分子的特性，A的离子产率可以被增强、减少或甚至完全抑制。这使得分析不确定，量化非常困难。在有机材料的情况下，有相当多的西姆斯和MALDI文献证明了化合物A与其分子邻居相比的相对碱度对（A+H）+物质形成的影响。因此，基质效应的一个重要贡献者可能是由于在离子发射区的质子的竞争。因此，在其中大部分分子相关离子通过质子转移形成的有机分析的情况下，预计大大增加发射区中质子源分子的密度将增加M+H或M-H产率。该项目将与小型离子束制造商Ionoptika Ltd合作，开发一种能够提供高密度H3 O+或巨型水团簇离子（H2O）nH+的水离子束系统（N=50至10000），在与样品表面碰撞时将产生高密度的质子相关物质，以提高（A+H）+的二次离子产率至少增加10倍，并且预计还具有缓解基质效应的额外好处。该项目将是仪器开发和水束特性的混合，然后对其操作进行研究。水束系统将建立完善和接口的离子光学柱以前开发的一个巨大的氩团束。研究了水束的最佳操作条件，并利用模型化合物系统研究了质子辅助离子产额提高的程度和机理。随后将进行多组分模型材料的研究，以研究水束对基质效应的影响和成像质谱定量分析的改进。时间允许的话，我们希望进行原理验证研究，以了解MALDI MS中水束的有益影响。该项目的成功结果将非常显着地增强西姆斯的能力和广泛应用，使分子亚微米分析和成像成为可能，大大改善基质效应的干扰，并显着提高定量测量。

项目成果

The influence of polyatomic primary ion chemistry on matrix effects in secondary ion mass spectrometry analysis.

多原子一次离子化学对二次离子质谱分析中基质效应的影响。

• DOI: 10.1002/rcm.8265
• 发表时间: 2018
• 期刊: RCM
• 作者: Alnajeebi AM

Comparison of C 60 and GCIB primary ion beams for the analysis of cancer cells and tumour sections

C 60 和 GCIB 一次离子束在癌细胞和肿瘤切片分析中的比较

• DOI: 10.1002/sia.4874
• 发表时间: 2012
• 期刊: Surface and Interface Analysis
• 影响因子: 1.7
• 作者: Fletcher J

Prospect of increasing secondary ion yields in ToF-SIMS using water cluster primary ion beams

• DOI: 10.1002/sia.5606
• 发表时间: 2014-11-01
• 期刊: SURFACE AND INTERFACE ANALYSIS
• 影响因子: 1.7
• 作者: Sheraz (nee Rabbani), S.;Barber, A.;Vickerman, J. C.
• 通讯作者: Vickerman, J. C.

Enhancing secondary ion yields in time of flight-secondary ion mass spectrometry using water cluster primary beams.

• DOI: 10.1021/ac4013732
• 发表时间: 2013-06-18
• 期刊: ANALYTICAL CHEMISTRY
• 影响因子: 7.4
• 作者: Sheraz nee Rabbani, Sadia;Barber, Andrew;Fletcher, John S.;Lockyer, Nicholas P.;Vickerman, John C.
• 通讯作者: Vickerman, John C.

Evaluation of biomolecular distributions in rat brain tissues by means of ToF-SIMS using a continuous beam of Ar clusters.

• DOI: 10.1116/1.4939251
• 发表时间: 2016-01
• 期刊: Biointerphases
• 影响因子: 2.1
• 作者: S. Nakano;Yuta Yokoyama;S. Aoyagi;Naoyuki Himi;J. Fletcher;N. Lockyer;Alex Henderson;J. Vickerman