权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Chemical Applications of Velocity and Spatial Imaging

速度和空间成像的化学应用

基本信息

批准号：
EP/L005913/1
负责人：
Michael Ashfold
金额：
$ 594.17万
依托单位：
University of Bristol
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2014
资助国家：
英国
起止时间：
2014 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FL005913%2F1
关键词：
Chemical Applications Velocity Spatial Imaging

项目摘要

Ion imaging, first demonstrated just 25 years ago, is already having a major impact on the way we explore molecular change (the very essence of chemistry) in many gas phase systems. The technique has features in common with mass spectrometry (MS). Both start by removing an electron from the target species, generating ions, i.e. charged molecules or fragments, which are then 'sorted' by their mass. In traditional MS, the species of interest is characterised by its spectrum of ion yield versus mass. Electron removal in most ion imaging experiments is induced by a short pulse of laser light; the resulting ions are then accelerated towards a time and position sensitive detector. Heavier ions travel more slowly, so one can image ions of just one particular mass by ensuring that the detector is only 'on' at the appropriate time. The spatial pattern of ion impacts that builds up on the detector when the experiment is repeated many times is visually intuitive, and provides quantitative energetic information about the reaction(s) that yields the monitored product. However, the read out time of current ion imaging detectors is too slow to allow imaging of ions with different mass formed in the same laser shot, and many species are not readily amenable to ionisation in current ion imaging schemes. Imaging all products from a given reaction is therefore time consuming (at best) and, at worst, impossible.We seek to solve both these limitations. Two of the team have already demonstrated new, much faster, time and position sensitive sensors capable of imaging multiple masses in a single shot experiment. This multimass imaging capability will be developed further and rolled-out for use and refinement across the team. We also propose new multiphoton ionization schemes as well as 'universal' ion formation methods based on use of shorter laser wavelengths or short duration pulses of energy selected electrons. The following over-arching scientific ambitions will proceed in parallel, and exploit the foregoing advances in ion imaging technology at the earliest possible opportunity:(i) We will use the latest ion imaging methods to explore molecular change in the gas phase, focusing on key families of (photo)chemical reactions: addition, dissociation, cyclisation and ring opening reactions of organic molecules, and metal-ligand and metal-cluster interactions. These choices reflect the importance of such reactions in synthesis, catalysis, etc., their amenability to complementary high level theory, and our ability to explore the same reactions in solution (using a new ultrafast pump-probe laser spectroscopy facility). Determining the extent to which the mechanisms and energetics of reactions established through exquisitely detailed gas phase studies can inform our understanding of reactivity in the condensed phase is a current 'hot' issue in chemical science, which the team is ideally placed to address.(ii) We will develop and exploit new multi-dimensional analytical methods with combined mass, structural and spatial resolution. Mass spectra usually show many peaks attributable to fragment ions, but the paths by which these are formed are often unclear. Imaging MS is proposed as a novel means of unravelling different routes to forming a given fragment ion; distinguishing and characterising such pathways can offer new insights into, for example, peptide structure. Yet more ambitious, we propose to combine multimass and spatial map imaging with existing laser desorption/ionisation methods to enable spatially resolved compositional analysis of surfaces and of samples on surfaces. Such a capability will offer new opportunities in diverse activities like tissue imaging (e.g. detection of metal ions within tissue specimens of relevance to understanding the failure of some metal-on-metal hip implants), forensic analysis (e.g. 'chemical' imaging of fingerprints, inks, dyes, pollens, etc) and parallel mass spectrometric sampling (e.g. of blood samples).

25年前首次展示的离子成像技术已经对我们探索许多气相系统中分子变化（化学的本质）的方式产生了重大影响。该技术具有与质谱法（MS）共同的特征。这两种方法都是从目标物质中去除一个电子，产生离子，即带电分子或碎片，然后根据它们的质量进行“分类”。在传统的MS中，感兴趣的物质的特征在于其离子产率与质量的光谱。在大多数离子成像实验中，电子去除是由激光的短脉冲引起的;然后将产生的离子加速到时间和位置敏感的检测器。较重的离子移动得更慢，因此通过确保检测器仅在适当的时间“打开”，可以仅对一个特定质量的离子进行成像。当实验重复多次时，在检测器上建立的离子撞击的空间图案在视觉上是直观的，并且提供关于产生所监测产物的反应的定量能量信息。然而，当前的离子成像检测器的读出时间太慢而不能允许对在相同激光照射中形成的具有不同质量的离子进行成像，并且许多种类在当前的离子成像方案中不容易经受电离。因此，对给定反应的所有产物进行成像是耗时的（最好的情况下），最坏的情况下是不可能的。我们试图解决这两个限制。其中两个团队已经展示了新的，更快的，时间和位置敏感的传感器，能够在单次实验中成像多个质量。这种多质量成像能力将得到进一步开发，并在整个团队中推广使用和改进。我们还提出了新的多光子电离方案，以及“通用”离子形成方法的基础上使用较短的激光波长或短时间脉冲的能量选择的电子。以下几项雄心勃勃的科学目标将同时进行，并尽早利用离子成像技术的上述进展：（i）我们将使用最新的离子成像方法来探索气相中的分子变化，重点是关键的（光）化学反应家族：有机分子的加成，解离，环化和开环反应，以及金属配体和金属簇的相互作用。这些选择反映了此类反应在合成、催化等方面的重要性，他们的顺从性，以补充高层次的理论，我们的能力，以探索相同的反应在解决方案（使用一个新的超快泵浦探测激光光谱设施）。确定通过精细详细的气相研究建立的反应机制和能量学在多大程度上可以告知我们对凝聚相中反应性的理解是化学科学中当前的“热点”问题，该团队非常适合解决这个问题。(ii)我们将开发和利用新的多维分析方法，结合质量，结构和空间分辨率。质谱通常显示出许多碎片离子的峰，但这些峰形成的路径往往不清楚。成像MS被提出作为一种新的手段，解开不同的路线，形成一个给定的碎片离子;区分和表征这样的途径可以提供新的见解，例如，肽结构。然而，更雄心勃勃的，我们建议结合联合收割机多质量和空间地图成像与现有的激光解吸/电离方法，使空间分辨成分分析的表面和表面上的样品。这种能力将为各种活动提供新的机会，如组织成像（例如，检测与理解某些金属对金属髋关节植入物失效相关的组织样本中的金属离子），法医分析（例如，指纹，墨水，染料，花粉等的“化学”成像）和平行质谱采样（例如，血液样本）。