Trapping Molecules on a Chip
Trapping Molecules on a Chip
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DOI：
10.1126/science.1175975
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发表时间：
2009-06
期刊：
影响因子：
56.9
通讯作者：
S. A. Meek;H. Conrad;G. Meijer
中科院分区：
文献类型：
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作者：
S. A. Meek;H. Conrad;G. Meijer
芯片微流控技术促进了化学合成平台的显著小型化；通过电子门控溶液流动和混合，分子反应可以在几厘米宽的芯片上进行。然而，当涉及到更基本的动力学研究时，这些研究涉及探测处于特定量子力学状态的气相分子，这些实验仍然倾向于需要更大的相互作用区域。Meek等人。(1699页)在后一种情况下向小型化迈进了一步，展示了在微电极装饰的芯片上分离出CO分子的冷气相束。这项技术依赖于快速调制的电场，通过偶极相互作用捕获并减缓传入的分子。一旦停止，这些分子可以在芯片上保持一段离散的时间，然后释放到探测器。将一束一氧化碳分子捕获到芯片上，应该可以进行化学动力学的基础研究。最近，磁性捕获芯片上的原子变得很简单，但类似的分子捕获已被证明是具有挑战性的。我们演示了使用超音速波束直接加载捕获芯片上方的一氧化碳分子。当分子到达芯片上方时，分子被限制在直径约20微米的管状电场陷阱中，中心位于芯片上方25微米处，这些电场陷阱与分子束一起以每秒数百米的速度移动。这些微型移动陷阱的阵列仅在几厘米的距离内停滞不前。在一定的保持时间后，分子再次加速离开芯片进行检测。这种加载和检测方法适用于各种极性分子，使在芯片上创建气相分子实验室成为可能。
CO on a Chip Microfluidics technology has facilitated remarkable miniaturization of chemical synthesis platforms; through electrically gated solution flow and mixing, molecular reactions can be carried out on chips several centimeters across. When it comes to more fundamental dynamics studies, though, which involve probing gas-phase molecules in specific quantum mechanical states, the experiments still tend to require much larger interaction areas. Meek et al. (p. 1699) take a step toward miniaturization in this latter regime by demonstrating the isolation of a cold gas-phase beam of CO molecules just above a microelectrode-decorated chip. The technique relies on rapidly modulated electric fields that trap and then slow down the incoming molecules through dipole interactions. Once brought to a stop, the molecules can be held on the chip for a discrete period and then released to a detector. Trapping a beam of carbon monoxide molecules onto a chip should enable fundamental studies of chemical dynamics. Magnetic trapping of atoms on chips has recently become straightforward, but analogous trapping of molecules has proved to be challenging. We demonstrated trapping of carbon monoxide molecules above a chip using direct loading from a supersonic beam. Upon arrival above the chip, the molecules are confined in tubular electric field traps ~20 micrometers in diameter, centered 25 micrometers above the chip, that move with the molecular beam at a velocity of several hundred meters per second. An array of these miniaturized moving traps is brought to a standstill over a distance of only a few centimeters. After a certain holding time, the molecules are accelerated off the chip again for detection. This loading and detection methodology is applicable to a wide variety of polar molecules, enabling the creation of a gas-phase molecular laboratory on a chip.