High-res infrared studies of molecular clusters, ethane, chemical intermediates and hydrocarbons

这项提议的重点有两个方面。首先是中性分子间范德华(VDW)力的实验研究。VDW作用力比化学键弱许多个数量级。然而，它们的作用范围要长得多，因此它们在分子簇、液体和固体的形成中发挥着重要作用。 通过探测团簇的性质，可以跟踪从气相到块体的演化过程。团簇是由结合的原子或分子组成的聚集体。有些团簇具有尺寸相关的物理化学性质，这些性质与块体的不同。其他的，如二氧化碳团簇，在大气和工业化学中引起了极大的兴趣。例如，在超临界条件下，二氧化碳被用作一种无害的工业溶剂。 这些分子间力可以通过高分辨率光谱学直接探测，这是我们打算使用的一种实验技术。我们将研究星系团，目的是回答一些基本问题，如“给定星系团大小的不同结构如何影响较大的星系团的增长？”以及“该系统是否有首选路径？”这些问题与大气化学、生物医学、电子学和材料科学有关。我们的实验结果也对弱力的量子化学计算提出了挑战，从而有助于推动理论的发展。反过来，该理论可以用于对具有生物学意义的大系统的计算，比如蛋白质折叠。 第二个目标是分析以实验室为基础的乙烷光谱，为汇编公认为国际标准的数据库提供数据。我们将提供中红外区域乙烷能带的频率和强度的量子力学模型。这里的挑战在于理解与CH3基团的大振幅扭曲在耦合其他振动模式中所起的作用有关的基本物理问题。解决这些基本物理问题的兴趣与CH3基团存在于许多较大的生物分子中这一事实有关，而正是这些基团的运动决定了这些系统的动力学性质和功能。我们实验室数据的最终用户是对地球和行星大气遥感、传输模拟、工业过程监测和污染监管研究感兴趣的科学家。 尽管我们提出的研究是基础性的，但它在具有实际意义的领域产生了重要的后果。加拿大将从拟议的项目中受益的最明显方式是通过培训学生和博士后研究员。在加拿大和其他地方，计算、光学、材料科学被用来指导新药的发现，研究全球变暖，预测天气模式等。保持增长速度和加拿大的技术实力需要训练有素的科学家。

The focus of this proposal is two-fold. First is experimental investigation of van der Waals (vdW) forces between neutral molecules. vdW forces are many orders of magnitude weaker than chemical bonds. However, they act over a much longer range and as a result they play an important role in formation of molecular clusters, liquids and solids. The evolution from gas phase to bulk can be traced by probing the properties of clusters. A cluster is an aggregate of bound atoms or molecules. Some clusters have size-dependent physicochemical properties which are different from those of the bulk. Others such as clusters of CO2 are of great interest in atmospheric and industrial chemistry. For example, under supercritical conditions CO2 is used a benign industrial solvent. These intermolecular forces can be directly probed by means of high-resolution spectroscopy, an experimental technique which we intend to use. We will investigate clusters with the aim of answering basic questions such as “how do differing structures of a given cluster size influence the growth of larger ones?” and “does the system has preferred pathways?” These questions are relevant in atmospheric chemistry, biomedical, electronics, and materials science. Our experimental results also provide a challenge to quantum chemical calculations of weak forces, which thereby helps to advance the state of the theory. The theory in turn can be used for calculations on large systems of biological significance, like protein folding. The second objective is to analyse laboratory based spectra of ethane to provide data for compilation on databases recognized as international standards. We will provide quantum mechanical models for frequency and intensity of ethane bands in the mid infrared region. Here, the challenge lies in understanding the basic physical questions relating to the role that large amplitude twisting of CH3 groups play in coupling the other vibrational modes. The interest in resolving such basic physical questions relates to the fact that CH3 groups are present in many larger bio-molecules and it is the motion of these groups that determine the dynamical properties and functions of these systems. The end users of our laboratory data are scientists with interest in terrestrial and planetary atmospheric remote sensing, transmission simulations, industrial process monitoring, and pollution regulatory studies. Although the research we propose is fundamental in nature it has important consequences in fields with practical importance. The most obvious way in which Canada will benefit from the proposed projects is via the training of students and postdoctoral fellows. In Canada and elsewhere computational, optical, material sciences are used to guide the discovery of new drugs, study global warming, predict weather patterns etc. Maintaining the pace of growth and Canada's technological prowess require well trained scientists.