Center for Nanoscale Science & Technology , Center for Nanoscale Science and Technology
Photoelectron spectroscopy (XPS, AES, XAS) and microscopy (PEEM, LEEM, SEM, SPEM) are in high demand 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 the dense media imposes serious experimental challenges. Currently, near ambient pressure electron spectroscopy is conducted using dexterously designed electron energy analyzers coupled with differentially pumped electron lenses, which made possible measurements at few hPa. We are developing an alternative truly atmospheric pressure approach that can be applied to a broad class of samples and be implemented in conventional laboratory-based instruments, as well as at synchrotron radiation facilities. We use ultrathin electron transparent but molecular impermeable membranes made of graphene to isolate the high pressure/liquid sample environment from the high vacuum electron detection system. We are working on combining this technology with state-of-the-art microfluidics. The systems of interest include but are not limited to electrochemical electrified interfaces, double layers, bio-medical interfaces, solvated nanoparticles, sensors, batteries, and other devices.
Kolmakov A, Gregoratti L, Kiskinova M, Guenther S: Recent Approaches for Bridging the Pressure Gap in Photoelectron Microspectroscopy. Topics in Catalysis 59: 448-468, 2016
Kraus J, Kolmakov A, et al: Photoelectron spectroscopy of wet and gaseous samples through electron transparent graphene membranes. Nanoscale 6: 14394-14403, 2014
Kolmakov A, et al: Graphene oxide windows for in situ environmental cell photoelectron spectroscopy. Nature Nanotechnology 6: 651-657, 2011
In situ spectromicroscopy; Atmospheric pressure XPS; Graphene; Microfluidics; Interfaces; Devices; Nanoparticles; PEEM; XAS