Ultrafast Electronic Decoherence Dynamics in Molecules

分子中的超快电子退相干动力学

基本信息

批准号：
2208061
负责人：
Niranjan Shivaram
金额：
$ 44.91万
依托单位：
Purdue University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2022
资助国家：
美国
起止时间：
2022-07-15 至 2025-06-30
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2208061&HistoricalAwards=false
关键词：
Ultrafast Electronic Decoherence Dynamics Molecules

项目摘要

In this project, the researchers will study the motion of electrons (charge dynamics) inside ionized molecules on time scales of a few femtoseconds (one femtosecond is a millionth of a billionth of a second). Understanding and controlling ultrafast charge dynamics in molecules is of fundamental importance in biochemical processes and the development of molecular scale electronic devices. The research group will use femtosecond laser pulses of various wavelengths to track the motion of the charge and obtain insight into the physical mechanisms that influence it. The results of this project will pave the path towards control of molecular charge dynamics, which is important for the design of laser-controlled chemical reactions and synthesis of quantum materials and devices. To fully realize this potential, a highly trained STEM workforce is essential. As part of this project, a diverse group of graduate and undergraduate students will be trained in ultrafast photon science and quantum science. A detailed understanding of various decoherence/dephasing processes in electronically excited molecules is essential for the development of quantum coherent control protocols for the laser driven control of molecular processes. This is particularly important in molecular ions in which femtosecond and attosecond charge migration dynamics are being intensely studied due to their importance in biochemical processes and charge transport phenomena. When a superposition of multiple ionic states with bandwidth of a few electron volts is created in molecules, electron correlation driven charge migration dynamics can be initiated. Understanding electronic decoherence mechanisms during charge migration is a critical first step towards achieving control of ultrafast charge dynamics in molecules. While multiple previous theoretical and experimental studies have explored charge migration using photoionization probes, nonlinear optical probes of such dynamics can offer a completely novel perspective. Similarly, when molecules are photoionized near shape resonances, the electron temporarily trapped in a shape resonance can affect the evolution of the molecular ion that may be left in a superposition of cationic states. A nonlinear optical measurement can probe the evolution of the molecular ion and shed light on the role played by the shape resonance. In this project, the research group will use nonlinear optical measurements of strong-field and extreme-ultraviolet ionized molecules to obtain direct and detailed information about electronic decoherence dynamics in molecular ions. The objectives are to (1) study electronic decoherence dynamics during strong-field initiated charge migration in molecules such as methyl bromide on few-femtosecond time scales and (2) study the effect of shape resonances on the ultrafast evolution of a molecular ion after XUV photoionization in molecules such as nitrogen and carbon dioxide.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在这个项目中，研究人员将按几个飞秒的时间尺度研究电子（电荷动力学）的运动（电荷动力学）的运动（一个飞秒是十亿秒的一百万秒）。在生化过程和分子尺度电子设备的发展中，理解和控制分子中的超快电荷动力学至关重要。研究小组将使用各种波长的飞秒激光脉冲来跟踪电荷的运动并深入了解影响其影响的物理机制。该项目的结果将为控制分子电荷动力学的路径铺平道路，这对于设计激光控制的化学反应以及量子材料和设备的合成非常重要。为了充分意识到这一潜力，训练有素的STEM劳动力至关重要。作为该项目的一部分，一组多样化的研究生和本科生将接受超快光子科学和量子科学的培训。对电子激发分子中各种破坏性/脱位过程的详细理解对于开发激光驱动分子过程的量子相干控制方案至关重要。这在分子离子中尤其重要，因为它们在生化过程中的重要性和电荷转运现象，因此对飞秒和attsond电荷迁移动力学进行了深入研究。当在分子中产生具有带宽的多个离子状态的叠加时，可以启动电子相关驱动的电荷迁移动力学。了解电荷迁移期间的电子破坏机制是实现分子超快电荷动力学的关键第一步。尽管以前的多个理论和实验研究已经使用光电离探针探索了电荷迁移，但这种动力学的非线性光学探针可以提供一种完全新颖的视角。同样，当分子在近形状共振上进行光电离子时，暂时捕获形状共振的电子会影响可能留在阳离子态叠加中的分子离子的演变。非线性光学测量可以探测分子离子的演变，并阐明形状共振的作用。在该项目中，研究小组将使用强场和极端硫化物离子化分子的非线性光学测量，以获取有关分子离子中电子腐蚀动力学的直接和详细信息。目的是（1）研究在强场期间，在诸如溴化甲基苯基等分子中的电荷迁移期间的电子变质动力学在很少的时间尺度上迁移，（2）研究形状共振对分子在诸如氮的传播型含氮的传播症状的分子离子的超快进化的影响认为值得通过基金会的智力优点和更广泛影响的评论标准来评估值得支持。