Pulsed Laser Desorption in Supersonic Beam Spectroscopy/ Mass Spectrometry

该项目涉及分析和表面化学的一般领域，以及激光光谱学和质谱学的子领域。这项实验活动的主旨是开发新的、高度选择性的非挥发性、热不稳定分子的分析方法，主要是生物上有意义的分子。为了达到这一目的，中性分子从表面解吸到气相中，然后通过超音速喷射膨胀冷却它们，这降低了它们的内部能量。一旦冷却，这些分子就会显示出非常鲜明的电子光谱。这些尖锐的特征使得共振双光子电离技术的应用具有高度的选择性，这些技术被用来电离这些分子，以便随后通过飞行时间质谱仪进行分析。激光解吸、超音速喷射膨胀、共振双光子电离和质谱学的结合为广泛样品的定性和定量表征提供了一种灵敏、高度选择性的分析工具。虽然这种混合方法将主要集中于药物和临床感兴趣的生物分子的分析，如儿茶酚胺、吲哚胺和小多肽，但这项研究的结果预计将在化学、生物和材料科学中产生广泛影响。

This project is in the general area of analytical and surface chemistry and in the subfields of laser spectroscopy and mass spectrometry. The thrust of this experimental activity is the development of new, highly selective methods of analysis for nonvolatile, thermally labile molecules, primarily biologically interesting ones. To accomplish this end, neutral molecules are desorbed from surfaces into the gas phase whereupon they are cooled through supersonic jet expansion which reduces their internal energy. Once cooled, these molecules exhibit quite sharp-featured electronic spectra. These sharp features enable the highly selective application of resonant two-photon ionization techniques which are used to ionize these molecules for subsequent analysis by time-of-flight mass spectrometry. This combination of laser desorption, supersonic jet expansion, resonant two-photon ionization, and mass spectrometry affords a sensitive, highly selective analytical tool for the qualitative and quantitative characterization of a broad spectrum of samples. Whereas this hybrid approach will be primarily focussed on the analysis of biomolecules of pharmaceutical and clinical interest such as catecholamines, indolamines, and small polypeptides, the results of this research are can be expected to impact broadly in the chemical, biological, and materials sciences.