Development of a Pulsed Helium Droplet Spectrometer

在化学研究仪器和设施（CRIF）计划的支持下，Andrey F.南加州大学的Vilesov将开发一种最先进的脉冲氦滴光谱仪。 他将开发和优化产生脉冲（50-100微秒）氦滴束的实验方法，以实现比当代连续波束高100 - 10，000倍的强度。 为了充分利用这一优势，他将开发的源与其他现代脉冲实验技术，如红外耗尽光谱，激光诱导荧光，激光光解，激光烧蚀和飞行时间（TOF）质谱。 这将促进涉及氦液滴的新实验，例如（一）大生物分子的研究;（二）大金属和分子团簇的组装和询问;（三）泵浦探测实验;（四）光化学反应的研究;以及（五）含有1亿多个原子的超大液滴的产生和使用。 这一发展将有助于建立He液滴光谱作为一种多功能的新工具，将使其具有成本效益，并将使主流科学家立即获得该技术。 最终的目标是发展一个脉冲氦液滴束装置的基础上，一个封闭的循环制冷机，配备了脉冲红外激光器和飞行时间质谱仪。 研究生将参与所有阶段，并将使用该仪器作为训练场之前，在自己的实验中集成脉冲喷嘴。 这一制度将使目前不可能实现的进步得以实现。 其他对光谱、分析和低温化学反应性和动力学感兴趣的化学家也可以从这种用户友好且具有成本效益的来源中受益匪浅。 预计将用于更广泛的应用领域，如大生物分子的询问或新纳米材料的开发。

With support from the Chemistry Research Instrumentation and Facilities (CRIF) Program, Prof. Andrey F. Vilesov of the University of Southern California will develop a state-of-the-art pulsed helium droplet spectrometer. He will develop and optimize experimental methods for the generation of pulsed (50-100 microseconds) helium droplet beams in order to achieve a factor of 100 - 10,000 higher intensity as compared to contemporary continuous-wave beams. To fully exploit this advantage, he will mate the developed source with other modern pulsed experimental techniques such as infrared depletion spectroscopy, laser-induced fluorescence, laser photolysis, laser ablation, and time-of-flight (TOF) mass spectroscopy. This will facilitate new experiments involving helium droplets, such as (i) studies of large bio-molecules; (ii) assembly and interrogation of large metal and molecular clusters; (iii) pump-probe experiments; (iv) studies of photochemical reactions; and (v) generation and use of very large droplets containing over 100 million atoms. This development will help to establish He droplet spectroscopy as a versatile new tool, will make it cost-effective, and will make the technique immediately accessible to mainstream scientists. The ultimate goal is the development of a pulsed helium droplet beam apparatus based on a closed-cycle refrigerator, equipped with pulsed infrared laser and a TOF mass spectrometer. Graduate students will be involved in all phases, and will use the instrument as a training ground prior to integrating the pulsed nozzle in their own experiments. This system will enable advances to be achieved that are not presently possible. Other chemists interested in spectroscopy, analytics and low temperature chemical reactivity and dynamics can also benefit greatly from this user-friendly and cost-effective source. Utilization to more applied areas such as interrogation of large biomolecules or development of new nano-materials is anticipated.