Visualizing Photon Induced Dynamics in Polyatomic Molecules using Femtosecond Pump-Probe Laser Pulses

PI及其团队将研究多原子分子与光的相互作用。分子是我们周围物质的原始组成部分，从我们呼吸的空气到我们饮用的水或我们用来治疗疾病的药物。光在人类的生活中起着至关重要的作用-例如，在我们的眼睛中发现的视紫红质分子在暴露于光时经历超快的转变，使我们能够看到。 这种转变，我们称之为异构化，也影响了技术应用，如分子发动机和可重写光学存储器。光对环状分子的影响的其他例子是皮肤中维生素D3的光合作用或光开关和纳米机械马达中的光电应用。这些光诱导的分子转化在物理学，化学和生物学中起着核心作用，因为它们在从蛋白质和抗生素的构建模块到工业应用的各种系统中都很重要。关键的兴趣是这些分子在吸收光后如何转变或断裂。 该项目由PI及其团队领导，旨在详细研究这些超快光子激活的基本量子力学机制。这个跨学科的研究计划整合了本科和研究生水平的教育，努力培养多样化的劳动力，并提供量子科学，编程和超快激光技术的全面培训。 这种培训有利于学生和博士后谁是下一代劳动力在学术界和各个行业的STEM领域。PI的研究已经并将继续为几个职业轨道培训学生和博士后。 以前NSF资助的学生和博士后在PI的研究实验室接受量子力学，技术和计算技能的培训，现在正在为学术界，国家实验室，国防和金融等行业的几个科学和技术领域做出贡献，开发新的激光技术和量子光学。这项研究计划通过其推广和代表性不足的群体的国家指导活动产生了额外的社会影响。 这个NSF研究计划将研究多原子分子中的时间分辨超快光诱导动力学，以提高对非绝热分子动力学的认识和理解，因为它们在基本物理和化学过程中发挥着重要作用。PI和她的团队将通过他们将研究的物理和化学机制，帮助理解光子能量从光到化学能的转换。特别是，PI的团队将研究光致化学反应过程中耦合的电子和核动力学与时间分辨率。具体来说，该团队的目标是在飞秒时间尺度上研究分子中的电子重排如何在光子吸收之后诱导和影响分子中的核运动和转化。该团队将详细研究内部分子能量转换，分子中的原子重排，通过异构化的分子转化，分子键延伸，从母体分子分离但留在附近并形成新分子的漫游分子片段，环状分子打开，键断裂，键形成和分子碎片。实验将采用紫外或红外激光泵浦探测技术进行。将使用冷靶反冲离子动量光谱（COLTRIMS）的符合技术检测所得带电碎片。离子动量成像将揭示潜在的光诱导分子动力学。这种准背景自由差分实验成像技术将提供新的，详细的信息，对上述竞争的物理和化学processes.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

The PI and her team will investigate the interaction of polyatomic molecules with light. Molecules are the primordial constituents of matter that surrounds us, from the air we breathe to the water we drink or the pharmaceutical drugs we take to cure diseases. Light plays a crucial role in humanity’s livelihood - for example, the rhodopsin molecules found in our eyes undergo an ultrafast transformation when exposed to light allowing us to see. This kind of transformation, which we call isomerization, impacts also technological applications such as molecular motors and re-writable optical memories. Other examples of the effect of light on cyclic molecules are the photo-synthesis of vitamin D3 in the skin or optoelectronic applications in optical switching and nanomechanical motors. These light-induced transformations of molecules hold a central role in physics, chemistry, and biology due to their importance in a wide variety of systems from the building blocks of proteins and antibiotics to industrial applications. Of crucial interest is how such molecules transform or break, after the absorption of light. This project, led by the PI and her team, is to investigate in detail these ultrafast photon-activated fundamental quantum mechanical mechanisms. This interdisciplinary research program integrates education at the undergraduate and graduate levels, strives to produce a diverse workforce and provides a comprehensive training in quantum science, programming, and ultrafast laser technology. This training benefits students and postdocs who are the next generation workforce in the STEM fields in academia and also in various industries. The PI’s research has, and will continue to train students and postdocs for several career tracks. Previous NSF funded students and postdocs trained with quantum mechanic, technical and computational skills in the PI’s research lab are now contributing to several areas of science and technology, in academia, national laboratories, defense, and industries such as financials, developing new laser technology and quantum optics. This research program has additional societal impact through its outreach and national mentoring activities of underrepresented groups. This NSF research program will investigate time-resolved ultrafast light-induced dynamics in polyatomic molecules in order to advance knowledge and understanding of non-adiabatic molecular dynamics due to their important role in fundamental physical and chemical processes. The PI and her team will contribute to the understanding of the conversion of photon energy from light into chemical energy via the physical and chemical mechanisms they will study. In particular, the PI’s team will examine the coupled electronic and nuclear dynamics during photo-induced chemical reactions with temporal resolution. Specifically, the team’s goal is to investigate, at the femtosecond timescale, how electronic rearrangement in molecules, subsequent to photon absorption, induces and effects nuclear motion and transformation in molecules. The team will examine in detail internal molecular energy conversion, atomic rearrangement in molecules, transformation of molecules through isomerization, molecular bond elongation, roaming molecular fragments that detach from the parent molecules but stay nearby and form new molecules, cyclic molecules opening, bond breaking, bond making and molecular fragmentation. The experiments will be conducted with Ultraviolet or Infrared laser pump-probe techniques. The resulting charged fragments will be detected using the coincidence technique of Cold-Target Recoil Ion Momentum Spectroscopy (COLTRIMS). The underlying photo-induced molecular dynamics will be revealed by ion-momentum imaging. This quasi-background free differential experimental imaging technique will provide new, detailed information on the aforementioned competing physical and chemical processes.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.