Innovative Laser Techniques for the Higher Resolution Electronic Spectroscopy of Molecular Ions

实验物理化学计划提供支持， 菲利普·M纽约州立大学石溪分校的约翰逊， 开发一种新的激光光谱学方法，称为光诱导里德伯 电离光谱（PIRI），它承诺了实质性的改进 在分子阳离子光谱中可达到的分辨率。 这 该技术依赖于这样一个事实，即中性的光学性质 一个电子被激发到高里德堡态的分子几乎 与相应离子的那些相同。 该方法通过以下步骤进行： 准备一个中性分子，在高n里德堡态下， 第一电离极限 这些里德伯分子的离子核是 然后由可调谐激光器电子激发， 当离子跃迁发生时的自电离。 离子的产生 产生的光谱相当于 光电子光谱，但不受分辨率的限制， 电子能量分析仪 PIRI能够检查激发的 离子的电子状态，这是无法达到以前的高 分辨率阈值电离技术 电子能谱和质量分析阈电离 谱 这项新技术将应用于几个小 大气层的兴趣分子，以探索参数和 该方法的能力，同时收集有关这些新信息 重要物种。 光诱导里德伯电离光谱或PIRI将使 分子阳离子的电子光谱， 以前无法实现的解决方案。 第一次，旋转和 离子的拥挤激发电子态的振动信息 将被收购。 最初的实验将集中在离子状态的 氧气、水、二氧化碳、氯化氢和二氧化硫。

The Experimental Physical Chemistry Program is providing support for Philip M. Johnson of the State University of New York-Stony Brook to develop a new method of laser spectroscopy, called photoinduced Rydberg ionization spectroscopy (PIRI), which promises a substantial improvement in the resolution attainable in the spectra of molecular cations. This technique relies upon the fact that the optical properties of neutral molecules with one electron excited to a high Rydberg state are almost identical to those of the corresponding ion. The method proceeds by preparing a neutral molecule in a high-n Rydberg state just below the first ionization limit. The ion cores of these Rydberg molecules are then electronically excited by a tunable laser, resulting in autoionization when an ion transition occurs. The production of ions with respect to wavelength produces spectra which are equivalent to photoelectron spectra but are not restricted by the resolution of electron energy analyzers. PIRI is able to examine the excited electronic states of ions which are not accessible to previous high resolution threshold ionization techniques such as zero kinetic energy electron spectroscopy and mass analyzed threshold ionization spectroscopy. This new technique will be applied to several small molecules of atmospheric interest in order to explore the parameters and capabilities of the method while gathering new information about these important species. Photoinduced Rydberg ionization spectroscopy or PIRI will enable the electronic spectroscopy of molecular cations to be observed with a resolution previously unattainable. For the first time, rotational and vibrational information on congested excited electronic states of ions will be acquired. Initial experiments will focus on ionic states of oxygen, water, carbon dioxide, hydrogen chloride and sulfur dioxide.