Exploring molecular structure and dynamics through Coulomb Explosion Imaging

通过库仑爆炸成像探索分子结构和动力学

• 批准号: RGPIN-2017-05741
• 负责人: Sanderson, joseph
• 金额: $ 1.53万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=664240
• 关键词: Exploring; molecular; structure; dynamics; through

The way that molecules change their shape (molecular dynamics) is perhaps their most important property at the heart of biological systems and therefore all life. The scientific quest to image molecular shape and how it changes, or can be made to change, has been one of the driving forces behind the development of powerful tools such as ultrashort laser sources (with pulses similar in length to the natural timescale of a molecular motion, one thousand million millionth of a second one femtosecond) or x-ray sources such as synchrotron facilities, which can excite a molecule to change shape with one high energy photon. A particularly appealing method for measuring molecular shape is Coulomb Explosion Imaging or CEI in which the molecule is ionized by removing as many electrons as possible and completely broken apart by either the laser pulse or the x-ray and literally explodes into atomic fragments. By determining what direction they came from, it is possible to actually make an image of he molecule at the point of explosion The method is important because it can image one molecule at a time in a gas and create an image which is accurate to the scale of atoms (Angstrom). Folded into the imaging process is a wealth of physics relating to the ionization process in the laser pulse, the molecular internal motion (vibration), dynamics initiated during ionization and the femtosecond timescales involved. The research program will focus on improving the quality of images particularly in the University of Waterloo where a laser is now dedicated to this study. In Waterloo we will tackle one of the biggest barriers to using the Coulomb imaging method with large molecules, namely the efficiency of the ion detection apparatus. This is typically only 65% which means that many molecules must be exploded before one gives complete fragmentation information. A new detector has become available which has the potential to get close to 100% efficiency, making the goal of imaging larger biologically significant molecules a possibility. We will test the new detectors in Waterloo and aim to image the largest molecules so far achieved. The program will use a number of approaches to help us understand the physical processes which lead to molecules changing shape, these will include using ionization by single Xray photons at the Canadian Light Source. One of the biggest motivations for using laser based imaging though is the controllability of lasers, which allows us to generate specific wavelengths which can initiate dynamics in a “pump” pulse followed by an imaging “probe” pulse which generates the Coulomb explosion and creates the image of the molecule, by varying the time between the two pulses we can record a “molecular movie” this will be further pursed in collaboration with the Advanced Laser Light Source, where we will attempt to improve on our already impressive movie of a proton moving from one end of an acetylene molecule to the other.

分子改变形状（分子动力学）的方式可能是它们在生物系统中心，因此生命的最重要特性。 The scientific quest to image molecular shape and how it changes, or can be made to change, has been one of the driving forces behind the development of powerful tools such as ultrashort laser sources (with pulses similar in length to the natural timescale of a molecular motion, one thousand million millionth of a second one femtosecond) or x-ray sources such as synchrotron facilities, which can excite a molecule to change shape with one high energy photon.测量分子形状的一种特别有吸引力的方法是库仑爆炸成像或CEI，其中通过消除尽可能多的电子设备而被激光脉冲或X射线完全崩溃，从而使分子被电离，并从字面上爆炸成原子片段。通过确定它们来自什么方向，可以在爆炸点实际制作分子的图像，该方法很重要，因为它可以一次在气体中对一个分子进行成像，并创建一个与原子（Angstrom）尺度准确的图像。折叠成成像过程的是与激光脉冲，分子内运动（振动），在电离期间启动的动力学以及涉及的femtsepsecond时尺度相关的电离过程的丰富物理学。该研究计划将着重于提高图像的质量，尤其是在滑铁卢大学，现在激光致力于这项研究。在滑铁卢，我们将解决使用大分子的库仑成像方法的最大障碍之一，即离子检测设备的效率。这通常只有65％，这意味着必须在提供完整的碎片信息之前探索许多分子。一个新的检测器已成为可用的，有可能获得接近100％的效率，从而使成像更大具有生物学意义的分子的目标成为可能性。我们将测试滑铁卢的新探测器，并旨在成像迄今为止最大的分子。该程序将使用多种方法来帮助我们了解导致分子变化形状的物理过程，这些过程包括使用加拿大光源的单X射线照片使用电离。使用基于激光的成像的最大动机之一是激光的可控性，这使我们能够生成特定的波长，这些波长可以在“泵”脉冲中启动动力学，然后是成像“探测”脉冲，可以产生库仑爆炸并创建分子的形象，并通过在两个脉冲之间创建“脉冲”，从而逐渐发展出来，我们可以在“脉冲”中逐渐探讨这一点。我们将尝试改进我们已经令人印象深刻的电影，该电影从乙炔分子的一端转变为另一端。