Theoretical and computational approaches to describing vibrational spectroscopy of water: bulk liquid, the liquid/vapor interface, and ice Ih

威斯康星大学麦迪逊分校的詹姆斯·斯金纳（James Skinner）获得了化学学部理论、模型和计算方法项目的奖励，他开发了描述大块液体、液体/蒸汽界面和冰中水的振动光谱的理论和计算方法。振动光谱实验包括频域红外，拉曼和和频率产生测量，以及最近的超快时域泵浦探针或回波研究。PI和他的研究小组开发了理论和计算模型来解释这些实验探针，重点是获得对水在不同阶段的结构和动力学特性的分子水平的理解。PI和他的同事们正在开发理论和计算模型来解决当前人们感兴趣的三个科学问题。第一种方法是通过泵探头旋转各向异性实验测量水和重水液体混合物中的振动能量传递。第二个涉及水在液/气界面的结构和动力学，通过相敏或外差检测振动和频率光谱来探测。第三部分是用单晶和多晶样品的拉曼光谱和红外光谱测量冰的振动本征态的性质。目标是建立统一的理论模型和方法，适用于所有变体的振动光谱，与实验进行比较，然后提供分子水平的理解。水是一种重要的物质，无论是气相、液相还是固相，它都是一种溶剂。尽管水分子本身很简单，但液态水、冰和水溶液的性质却很复杂，目前还没有完全理解。振动光谱学在阐明水的缩合相结构和动力学方面起着重要的作用，因为局部OH拉伸振动的跃迁频率对其氢键环境非常敏感。水在从生物学到地球和大气科学的各个领域都扮演着重要的角色。PI已经制定了一项扩展计划，包括针对高中教师的网络水研讨会，以及麦迪逊地区初中和高中科学课程的水巡回路演。

James Skinner of the University of Wisconsin, Madison is supported by an award from the Theory, Models and Computational Methods program in the Chemistry Division to develop theoretical and computational approaches that describe the vibrational spectroscopy of water in the bulk liquid, the liquid/vapor interface, and ice. Vibrational spectroscopy experiments include frequency-domain infrared, Raman, and sum-frequency-generation measurements, as well as very recent ultrafast time-domain pump-probe or echo studies. The PI and his research group develop theoretical and computational models for the interpretation of these experimental probes, with a focus on obtaining a molecular-level understanding of the structural and dynamical properties of water in its various phases. The PI and his coworkers are developing theoretical and computational models to tackle three scientific problems of current interest. The first involves vibrational energy transfer in liquid mixtures of water and heavy water, as measured by pump probe rotational anisotropy experiments. The second involves the structure and dynamics of water at the liquid/vapor interface, as probed by phase-sensitive or heterodyne detected vibrational sum-frequency spectroscopy. The third involves the nature of vibrational eigenstates in ice as measured by Raman and infrared spectra of single crystal and polycrystalline samples. The goal is to develop unified theoretical models and approaches that are applicable to all variants of vibrational spectroscopy, to compare with experiment, and then to provide molecular-level understanding.Water is an important substance, in each of its gas, liquid, or solid phases, and as a solvent. Despite the simplicity of the water molecule itself, the properties of liquid water, ice, and aqueous solutions are complex, and a complete understanding is still not at hand. Vibrational spectroscopy plays an important role in elucidating the structure and dynamics of water in its condensed phases, because the transition frequency of a local OH stretch vibration is exquisitely sensitive to its hydrogen-bonding environment. Water plays an important role in diverse fields from biology, to earth and atmospheric sciences. The PI has developed an outreach program involving web seminars on water directed to high school teachers, and a traveling road show on water for middle and high school science classes in the Madison area.