Photoelectron Momentum Microscope at BL6U of UVSOR-III synchrotron

Abstract

Photoelectron spectroscopy resolved in three-dimensional momentum space with a microscopic field of view is realized by combining a so-called Momentum Microscope with a soft X-ray synchrotron radiation source. A new experimental station for momentum-resolved photoelectron micro-spectroscopy and spectro-microscopy has been built at BL6U, an undulator-based soft X-ray beamline of the UVSOR synchrotron facility. This experimental station specializes in characterizing the electronic structure of surface atomic sites, thin films, molecular adsorbates, and bulk crystals. The instrument details are described along with possible measurement techniques.

Contrast Inversion of Photoelectron Spectro-microscopy Image

“…Thus, the reason of such results is still unclear and not trivial. Previously, we reported the observation of contrast inversion in the photoelectron images of a silicon substrate with gold checkerboard patterns [18]. Here, we further investigated the contrast formation of photoelectron images.…”

“…Details of the momentum microscope experimental station are described elsewhere [18]. In this section, we have reposted some important explanations needed for the following discussion.…”

“…This approach significantly reduces the time required to retrieve x−y images and k x −k y patterns. At BL6U of UVSOR synchrotron facility, a single-HDA-type momentum microscope, KREIOS 150 MM (SPECS Surface Nano Analysis GmbH), was installed and is now in operation [18].…”

Classification of the symmetry of photoelectron dichroism broken by light

“…7(a). Such a setup cannot be realized in the present ARToF system because the analyzer blocks the light, but can be when a port is utilized to let light through slit-less-type analyzers such as the display-type analyzers [42], momentum microscopes [44,47] and hemispherical analyzers equipped with electron deflectors [54]. In fact, the normal-incidence configuration was demonstrated and linear-polarization dependence was studied for 1T -TaS 2 [76] by using the display-type analyzer [19].…”

“…The experimental setup is unique in that the entity of the sample and electron analyzer has the symmetry of C ∞v during the data acquisition. The key to the highsymmetry setup is twofold: (1) We prepared a sample that is effectively C ∞v ; (2) we used a slit-less photoelectron analyzer [42][43][44][45][46][47].…”