Center for Functional Nanomaterials Seminar

Bridging the "pressure gap" between traditional high-vacuum analytical tools such as SEM, XPS, AES, PEEM, SPEM and realistic sample environments is major experimental challenge to study interfacial processes relevant to energy/environmental research, catalysis and biomedical applications. The instrumentation for (near) atmospheric pressure electron based spectromicroscopies currently evolves in two directions: (i) via development of the differential pumping stages coupled with sophisticated electron optics and sample delivery systems [1]; and more recently, (ii) via implementation of the electron transparent membranes that separate the liquids or dense gaseous environments from the standard UHV instrumentation [2, 3]. In the latter case, the modification of the standard analytical instrumentation is not required since it can be transferred to the sample stage that can effectively employ already existing lab-on-a-chip MEMS technologies. Here we highlight the capabilities of this membrane approach and future trends [4]. We discuss current graphene liquid cells designs including microchannel arrays (MCA)[5] and their applications for electrochemical studies[6]. Such designs allow for high throughput combinatorial data mining algorithms such as principle component analysis, clustering, Bayesian inference methods etc. This is particularly important when multi-dimensional/ hyperspectral datasets are collected [3]. The next generation of the UHV compatible graphene microfluidic sample platform will be discussed. References: [1] D. F. Ogletree, H. Bluhm, G. Lebedev, C. S. Fadley, Z. Hussain, and M. Salmeron, "A differentially pumped electrostatic lens system for photoemission studies in the millibar range," Review of Scientific Instruments, vol. 73, no. 11, pp. 3872-3877, 2002. [2] A. Kolmakov et al., "Graphene oxide windows for in situ environmental cell photoelectron spectroscopy," Natu