Nanospectroscopy highlights

Space charge artifacts in PEEM have been often observed in PEEM instruments employing ultra-bright laser sources. In this work, we study artifacts in XPEEM imaging and spectroscopy using the high intensity synchrotron radiation produced by an undulator source and  report on image blur and energy broadening effects at extremely high flux densities. We have recently demonstrated that Coulomb interactions between photoelectrons along the PEEM optics result in the degradation of both the microscope lateral and energy resolution, due to the combined action of the Loeffler and Boersch effects. At a flux of 2×10¹³ photons/s, the lateral resolution in XPEEM imaging with either core level or secondary electrons deteriorates to more than 50 nm. Broadening of the

Fermi level up to several hundred meV and spectral shift to higher kinetic energies are observed at similar photon fluxes, which correspond to peak electron photocurrents of a few μA in our estimates. These effects might have severe implications for the emerging generation of aberration corrected PEEM instruments, as they impose a physical limitation on the best lateral and energy resolution that can be achieved in XPEEM

Retrieve article

Image blur and energy broadening effects in XPEEM;
A. Locatelli, T.O. Menteş, M.Á. Niño, and E. Bauer;
Ultramicroscopy, 111, 1447-1454 (2011);
doi: 10.1016/j.ultramic.2010.12.020.