Pupa Gilbert (née Gelsomina De Stasio)
Research Group

We have been investigating the electronic structure, crystallographic orientation and chemical composition of a wide variety of specimens by X-ray PhotoElectron Emission spectroMicroscopy (X-PEEM), with synchrotron illumination. X-PEEM spectromicroscopy provides X-ray Absorption Near Edge Structure (XANES) spectroscopy, that is, stacks of approximately 200 X-PEEM images are collected while scanning the photon energy. Each pixel in this stack of images provides a full XANES spectrum.

Cells, tissues, minerals, proteins and biominerals are routinely imaged and analyzed with the Spectromicroscope for PHotoelectron Imaging of Nanostructures with X-rays (SPHINX) spectromicroscope. Analysis can be done with high spectral and spatial resolution with X-PEEM and XANES spectromicroscopy using our SPHINX instrument. This instrument has a best resolution of 10 nm. Its uses are broad, from archaeology to geology; from chemistry to biology. The only requirements are that the samples of interest be compatible with ultra-high vacuum, smooth, and flat.

We recently started using PEEM-3 at the ALS, which uses an elliptically polarizing undulator (EPU) as its source, and is thus well-suited for polarization-dependent imaging contrast and crystal orientation analysis in biominerals