title: Theoretical estimates of spherical and chromatic aberration in photoemission electron microscopy.
abstract: We present theoretical estimates of the mean coefficients of spherical and chromatic aberration for low energy photoemission electron microscopy (PEEM). Using simple analytic models, we find that the aberration coefficients depend primarily on the difference between the photon energy and the photoemission threshold, as expected. However, the shape of the photoelectron spectral distribution impacts the coefficients by up to 30%. These estimates should allow more precise correction of aberration in PEEM in experimental situations where the aberration coefficients and precise electron energy distribution cannot be readily measured.
authors.affiliation: Portland State University, Department of Physics, PO Box 751, Portland, OR 97207, United States. Electronic address: fit@pdx.edu.
authors.forename: J P S
authors.initials: JPS
authors.lastname: Fitzgerald
authors.affiliation: Portland State University, Department of Physics, PO Box 751, Portland, OR 97207, United States.
authors.forename: R C
authors.initials: RC
authors.lastname: Word
authors.affiliation: Portland State University, Department of Physics, PO Box 751, Portland, OR 97207, United States.
authors.forename: R
authors.initials: R
authors.lastname: Könenkamp
keywords: Aberration correction; Chromatic aberration; Electron optics; PEEM; Photoemission electron microscopy; Spherical aberration