Molecular Rydberg Spectra Encode Intramolecular Dynamics

分子通常包含许多电子，并且由于带负电，这些电子在空间中移动时相互排斥。电子-电子排斥使得精确计算分子的性质和行为变得困难，并且仍然是化学科学的最大挑战之一。在化学系化学结构、动力学和机理项目的支持下，马萨诸塞州理工学院的罗伯特·菲尔德教授和他的研究小组正在利用先进的激光和微波光谱技术制备和研究所谓的里德伯分子。里德伯分子是一个正常的分子，其中一个电子被激发（通过激光）到如此高的轨道，该系统类似于一个简单的氢原子（一个带负电荷的电子加上一个带正电荷的质子）。由于它们的简单性，里德伯分子可以用理论更准确地建模，并且可以更准确地回答其他问题，例如，电子如何与光相互作用？或者说，电子如何彼此交换能量，以及如何与分子中带正电的“离子核”交换能量？这个研究项目挑战了关于分子结构以及它们如何与光相互作用的传统思维。该项目的发现也可能对量子计算的新领域产生影响。从事该项目的博士后科学家和本科生研究人员正在获得尖端激光/微波技术和计算化学方面的经验。该项目侧重于三个实验目标，并针对三个基本问题的答案。对主要实验组分的特性进行了独立论证。实验目标是：（i）以每秒100，000个分辨率元素的光谱速度记录Rydberg-Rydberg光谱，由一套实时诊断组织和分配;（ii）利用系统的光谱访问核心非穿透Rydberg状态，绕过以前被认为是不可能的快速非辐射衰变区域（称为“死亡区”）;（iii）利用超辐射的里德伯-里德伯过渡，以获得有关量子多体相互作用的信息。 如果这些实验是成功的，我们的方法和结果将挑战光谱学家想象和目标的气相分子光谱学的新领域。 该项目正在导致确定分子离子多极矩和极化率的新方法，这对于建立与天体物理学和新技术有关的致密等离子体模型至关重要。 多通道量子亏损理论的完善承诺的先验校准方法的生产状态选择的分子离子设计新的类方案的外部控制的分子dynamics.This奖项反映了NSF的法定使命，并已被认为是值得的支持，通过评估使用基金会的智力价值和更广泛的影响审查标准。

Molecules typically contain many electrons, and, being negatively charged, these electrons repel each other as they move in space. Electron-electron repulsion makes it difficult to calculate precisely the properties and behaviors of molecules, and remains one of the greatest challenges for the science of chemistry. With the support of the Chemical Structure, Dynamics and Mechanisms-A Program of the Division of Chemistry, Professor Robert Field and his research team at the Massachusetts Institute of Technology are using advanced laser and microwave spectroscopy techniques to prepare and interrogate what are called Rydberg molecules. A Rydberg molecule is a normal molecule in which one electron has been excited (by laser light) to such a high orbit that the system resembles a simple hydrogen atom (one negatively charged electron plus one positively charged proton). Because of their simplicity, Rydberg molecules can be modeled more accurately with theory, and it becomes possible to answer other questions with more accuracy, for example, how do electrons interact with light? Or how do electrons exchange energy with each other and with the positive-charged "ion core" of the molecule? This research project challenges conventional thinking about the structure of molecules and how they interact with light. The discoveries from this project may also have implications for the new field of quantum computing. The post-doctoral scientists and undergraduate researchers engaged in this project are gaining experience in both cutting-edge laser/microwave technology and computational chemistry. This project is focused on three experimental goals and targeted at answers to three fundamental questions. The feasibilities of the principal experimental components have been independently demonstrated. The experimental goals are: (i) to record Rydberg-Rydberg spectra at a spectral velocity of 100,000 resolution elements per second, organized and assigned by a suite of on-the-fly diagnostics; (ii) to exploit systematic spectroscopic access to core-nonpenetrating Rydberg states, bypassing a region of fast nonradiative decay previously deemed to be impassible (called the "zone of death"); (iii) to exploit superradiance on Rydberg-Rydberg transitions to obtain information about quantum many-body interactions. If these experiments are successful, our methods and results will challenge spectroscopists to imagine and target new frontiers for the spectroscopy of gas phase molecules. This project is leading to new methods for the determination of multipole moments an polarizabilities of molecular-ions, which are essential to model dense plasmas, which are relevant to astrophysics and new technologies. The refinement of Multi-channel Quantum Defect Theory promises a priori calibrated methods for production of state-selected molecular ions devise new classes of schemes for external control of molecular dynamics.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.