Spontaneous and Forced Modulation of Electrosprays

乔治华盛顿大学的Akos Vertes教授在分析和表面化学项目的支持下，研究了在电喷雾条件下液体分子离子的形成。尽管在这一领域的工作历史悠久，以及电喷雾电离质谱（ESI-MS）在生物分析中的重要性，但我们对相关现象的理解细节仍未解决。这部分是由于复杂的电流体动力学，必须或多或少地同时解决。随着我们对离子溶剂化的理解变得更加复杂，其他的复杂情况也变得明显起来。深入了解1)液体流分散成带电液滴和2)样品离子从这些液滴中解放的最终阶段。其中一个实验是利用喷雾电压调节电喷雾，使喷雾与离子的重复引入同步到质谱仪的飞行时间。相多普勒风速法、质谱法和显微成像被用于将（初级）液滴大小和速度分布与观测到的质谱相关联。分子动力学用于研究液滴的破裂和离子的形成。约翰·芬恩（John Fenn）最近因电喷雾电离质谱（ESI）获得诺贝尔奖，这是对其影响，特别是其生化应用的最公开认可。提高对ESI的理解很有可能带来更大的影响。此外，这项关于液滴和离子形成的基础工作可能会对云的形成、吸入毒理学和药物输送、纳米加工和操作以及印刷等多种过程产生科学和技术影响。

Professor Akos Vertes of George Washington University is supported by the Analytical and Surface Chemistry Program to study the formation of ions from molecules in liquids under electrospray conditions. In spite of the long history of work in this area as well as the importance of Electrospray Ionization Mass Spectrometry (ESI-MS) in bioanalysis, details of our understanding of the associated phenomena remain unresolved. This is due in part to the complicated electro-hydrodynamics that must be addressed more or less simultaneously. Additional complications have become apparent as our understanding of ionic solvation has become more sophisticated. Insight is sought into 1) dispersion of a liquid stream into electrically charged droplets and 2) the ultimate stage of liberation of sample ions from these droplets. One experiment is to modulate the electrospray using the spraying voltage in order to synchronize the spray with the repetitive introduction of ions into the time of flight mass analyzer. Phase Doppler anemometry, mass spectrometry and microscopic imaging are used to correlate (primary) droplet size and velocity distributions with the observed mass spectra. Molecular dynamics is used to study droplet breakup and ion formation. John Fenn's recent Nobel Prize for Electrospray Ionization Mass Spectroscopy (ESI) is only the most public recognition of its impact, and in particular, its biochemical applications. Improved understanding of ESI is highly likely to lead to even more impact. In addition, this fundamental work on droplet and ion formation is likely to have scientific and technical impact in diverse processes such as formation of clouds, inhalation toxicology and drug delivery, nano-processing and manipulation, and printing.