Kraus Jürgen, Reichelt Robert, Günther Sebastian, Gregoratti Luca, Amati Matteo, Kiskinova Maya, Yulaev Alexander, Vlassiouk Ivan, Kolmakov Andrei
Technische Universität München, Chemie Department, Lichtenbergstr. 4, D-85748 Garching, Germany.
Nanoscale. 2014 Nov 6;6(23):14394-403. doi: 10.1039/c4nr03561e.
Photoelectron spectroscopy (PES) and microscopy are highly important for exploring morphologically and chemically complex liquid-gas, solid-liquid and solid-gas interfaces under realistic conditions, but the very small electron mean free path inside dense media imposes serious experimental challenges. Currently, near ambient pressure PES is conducted using dexterously designed electron energy analyzers coupled with differentially pumped electron lenses which make it possible to conduct PES measurements at a few hPa. This report proposes an alternative ambient pressure approach that can be applied to a broad class of samples and be implemented in conventional PES instruments. It uses ultrathin electron transparent but molecular impermeable membranes to isolate the high pressure sample environment from the high vacuum PES detection system. We demonstrate that the separating graphene membrane windows are both mechanically robust and sufficiently transparent for electrons in a wide energy range to allow soft X-ray PES of liquid and gaseous water. The performed proof-of-principle experiments confirm the possibility to probe vacuum-incompatible toxic or reactive samples placed inside such hermetic, gas flow or fluidic environmental cells.
光电子能谱（PES）和显微镜技术对于在实际条件下探索形态和化学复杂的液-气、固-液和固-气界面非常重要，但致密介质内部非常小的电子平均自由程给实验带来了严峻挑战。目前，近环境压力PES是使用精心设计的电子能量分析仪与差分抽运电子透镜相结合来进行的，这使得在几hPa的压力下进行PES测量成为可能。本报告提出了一种替代的环境压力方法，该方法可应用于广泛的样品类型，并可在传统的PES仪器中实现。它使用超薄的电子透明但分子不可渗透的膜，将高压样品环境与高真空PES检测系统隔离开来。我们证明，分离石墨烯膜窗口在机械上是坚固的，并且对于宽能量范围内的电子具有足够的透明度，从而能够对液态和气态水进行软X射线PES分析。所进行的原理验证实验证实了探测放置在这种密封、气流或流体环境单元内与真空不相容的有毒或反应性样品的可能性。
