Instrument Development: a High Density Source of Cold, Slow Molecules

在这个项目中，由化学部的化学测量和成像计划资助，教授。德克萨斯农工大学的达德利赫施巴赫和伊戈尔·柳克休托夫试图开发一种仪器，能够以低至5米/秒的速度（基准）传送密度高达1012厘米-3的冷分子束。 该仪器是一个脉冲，反向旋转超声源（PCRS），任何分子作为气体可以被减慢（或加速）。 在如此低的速度下，这样的密度比目前通过其他方式获得的密度大大约四个数量级。~ 5 m/s的非常慢的光束对于许多需要捕获分子的实验是必不可少的。 预期的束密度，通常为1010 cm-3，是必不可少的，使捕获的分子随后冷却到超冷领域。 在不同的模式中使用，对于碰撞的研究，通过将PCRS与同向固定源配对并通过调节转子速度来紧密匹配束速度，可以获得非常低的相对动能。 这种合并波束的能力是广泛适用的。 它将开辟化学反应动力学的“物质波”或“超量子”领域，在那里，碰撞的德布罗意波长远远超过反应物分子的大小。该项目还包括开发一种适用于具有磁矩的分子的辅助仪器。 它是一种单级磁减速器（SSMD），设计用于与PCRS结合使用。 初步版本的SSMD的计算机模拟表明，只有7厘米长的脉冲场，抛物线的轮廓和强度5特斯拉，可以减速O2从50米/秒到2或3米/秒。结合PCRS + SSMD仪器将是紧凑的，强大的，简单的构造和操作。该项目将提供工具，将显着推进实验研究探索，并最终使用非常慢的分子的新特性。 从信息处理（量子计算机）到重力探测器的未来应用已经被预测将从慢分子技术中出现。这项研究的冒险性激发了学生和广大公众的兴趣。 本科生（由REU资助或由TAMU支持）以及研究生将做出重大贡献。 这项工作涉及设备的设计研究，包括许多桌面组件和实验协议，从而提供计算机模拟和其他实用艺术的经验。 这两个PI都是关于教学和指导学生的福音派，并努力改善K-12科学教育和公众对科学的理解。 与该项目直接相关的是为高中生举办的“德克萨斯州最酷的地方”暑期课程计划，以及为包括高中生和中学生在内的公众举办的两个系列讲座“超冷世界”和“纳米世界的奇才”。

In this project, funded by the Chemical Measurements and Imaging Program of the Chemistry Division, Profs. Dudley Herschbach and Igor Lyuksyutov of Texas A&M University seek to develop an instrument capable of delivering beams of cold molecules with densities up to 1012 cm-3 at speeds as low as 5 m/s (the benchmark). The instrument is a pulsed, counter-rotating supersonic source (PCRS), with which any molecule available as a gas can be slowed (or speeded). Such densities at speeds so low are about four orders of magnitude larger than currently available by other means. Very slow beams of ~ 5 m/s are essential for many experiments that require trapping molecules. Anticipated beam densities, typically 1010 cm-3, are essemtial to enable the trapped molecules to be subsequently cooled down to the ultracold realm. Used in a different mode, for study of collisions, very low relative kinetic energies can be attained by pairing the PCRS with a codirectional stationary source and closely matching the beam velocities by adjusting the rotor speed. This merged-beam capability is widely applicable. It will open up the "matterwave" or "hyperquantum" realm of chemical reaction dynamics, where collisional deBroglie wavelengths much exceed the size of reactant molecules. The project also includes the development of an auxiliary instrument, applicable to molecules with magnetic moments. It is a single-stage magnetic decelerator (SSMD), designed to operate in combination with the PCRS. Computer simulations for a preliminary version of the SSMD demonstrate that a pulsed field only 7 cm long, with parabolic profile and strength 5 Tesla, can decelerate O2 from 50 m/s to 2 or 3 m/s. The combined PCRS + SSMD instrument will be compact, robust, simple to construct and operate.This project will provide tools that will significantly advance experimental research exploring and eventually using the novel properties of very slow molecules. Futuristic applications from information processing (quantum computers) to gravity detectors have been predicted to emerge from slow molecule technology. The adventurous character of the research fosters interest both among students and the wider public. Undergraduate students (supported either by REU funding or by TAMU) as well as graduate students will contribute significantly. The work involves design studies for apparatus, including many table-top components, and experimental protocols, thereby providing experience in computer simulations and other practical arts. Both PIs are evangelical about teaching and mentoring students and have undertaken efforts to improve K-12 science education and public understanding of science. Directly linked to this project are plans for a "Coolest Place in Texas" summer program for high school students and a pair of lecture series "The Ultracold World" and "Wizards of the NanoWorld" for the general public, including high school and middle school students.