High resolution laser spectroscopy of small gas-phase metal-ligand molecules

该研究计划旨在利用激光光谱学了解小的气相金属配体分子的基本结构和性质。这些分子通过各种方法产生，并用激光激发到更高的能量状态，然后通过发光衰减回较低的能级。通过检测这种发射的光或观察分子吸收辐射的能量，可以详细了解分子中的键合，结构和相互作用。例如，这一信息对于理解大气、空间以及任何表面化学或催化过程中发生的化学和物理过程都很重要。 分子在冷分子束（分子的明确定义的流）中产生，以给出高分辨率和简化的光谱。在实验中，一个高功率激光聚焦到一个金属靶上举行的脉冲气体喷嘴前。来自靶的汽化原子与从喷嘴流出的气体中的试剂反应。然后，气体通过一个小孔膨胀到真空系统中，产生光束。用可调谐激光器探测下游分子，并观察到作为频率函数的分子反射。 研究中针对两组分子：A）双原子金属配体物质（DML）和B）小金属配体多原子（MLP）。我们正在测量许多DML（RhBr、RhP、IrP等），首次观测到这些分子的吸收，以全面研究成键特性，并为某些具有催化和天体物理意义的分子提供光谱信息。有很多MLP。我们对具有天体物理学重要性或对理解催化和化学吸附重要的MLP感兴趣。我们最近研究的几种MLP分子有：MgCCH/C4 H、CaCCH/CCD、Ca/SrOCH 3。我们对金属单羰基化合物特别感兴趣。这些分子在表面化学和催化反应中很重要，但很少有气相研究。我们将首次研究这些物种，以提供有关其特性的新信息。

This research program is geared towards understanding the fundamental structure and properties of small, gas-phase, metal-ligand molecules using laser spectroscopy. The molecules are produced by various methods and excited with a laser to higher energy states from which they can decay back to lower energy levels by emitting light. By detecting either this emitted light or observing at which energy the molecules absorb the radiation, a detailed understanding of the bonding, structure and interactions in the molecules can be gained. This information is important, for example, in understanding both the chemical and physical processes occurring in the atmosphere, in space, and in any surface chemistry or catalytic process. The molecules are produced in cold molecular beams (well defined streams of molecules) to give highly resolved and simplified spectra. In the experiments, a high power laser is focussed onto a metal target held in front of a pulsed gas nozzle. Vaporized atoms from the target react with a reagent in the gas flowing from the nozzle. The gases then expand through a small hole into a vacuum system creating the beam. The molecules are probed downstream with a tunable laser and molecular absorptions are observed as a function of frequency. Two groups of molecules are targeted in the research: A) diatomic metal-ligand species (DMLs), and B) small metal-ligand polyatomics (MLPs). We are measuring a number of DMLs (RhBr, RhP,IrP, ...), where absorptions for these molecules are being observed for the first time, to comprehensively study the bonding characteristics and provide spectral information for certain molecules of catalytic and astrophysical interest. There are many MLPs. We are interested in MLPs that have astrophysical importance or are important for understanding catalysis and chemisorptions. A few MLP molecules that we have studied recently are: MgCCH/C4H, CaCCH/CCD, Ca/SrOCH3. We are particularly interested in metal monocarbonyls. Few gas-phase studies of these molecules, which are important in surface chemistry and catalytic reactions, exist. We will examine these species for the first time to provide new information on their properties.