microARPES and nanoARPES at diffraction-limited light sources: opportunities and performance gains

Abstract

The scientific opportunities for microARPES and nanoARPES techniques are discussed, and the benefits to these techniques at diffraction-limited light sources are presented, in particular the impact on spectromicroscopic ARPES (angle-resolved photoemission spectroscopy) of upgrading the Advanced Light Source to diffraction-limited performance. The most important consideration is whether the space-charge broadening, impacting the energy and momentum resolution, will limit the possible benefits for ARPES. Calculations of energy broadening due to space-charge effects will be presented over a wide range of parameters, and optimum conditions for ARPES will be discussed. The conclusion is that spectromicroscopic ARPES will greatly benefit from the advent of diffraction-limited light sources; space-charge broadening effects will not be a limiting factor.

Angle-resolved photoemission spectroscopy and its application to topological materials

“…However, many interesting materials or single-crystalline domains are smaller than 100 μm, such as heterostructures and microscale and nanoscale materials. In consideration of the above cases, spatially resolved ARPES with micrometre or sub-micrometre spatial resolution has been developed at several synchrotron light sources 14,[48][49][50][51]214 .…”

“…To focus X-rays to a microsized or nanosized spot at the sample, advanced optics have been developed, including Schwarzschild optics 48 and the Fresnel zone plate 214 . As an example, the nano-ARPES end-station 50 at the MAESTRO beamline at the Advanced Light Source (California, USA) uses a Fresnel zone plate to focus the beam, followed by an order-sorting aperture to eliminate high-diffraction orders ( fig. 7a).…”

Synchrotron radiation: A continuing revolution in X-ray science—Diffraction limited storage rings and beyond

“…For example superconducting and normal phases might coexist under certain conditions or metallic and insulating phases might be present in the same sample. Being able to probe the electronic properties of individual regions of a multi phased sample definitely generates new perspectives for characterizing and understanding these complex materials [11].…”

Magnetic imaging with polarized soft x-rays

“…Although x-rays have been discovered more than 100 years ago and their short wavelength was immediately recognized as a potential push towards higher spatial resolution compared to optical microscopies, it was the lack of appropriate x-ray optics that prevented x-ray microscopies for nearly a century from being established. It was not until the mid-1980s when not only x-ray sources from synchrotron storage rings became available, but also the capability of nanopatterning materials by ebeam lithography that was originally developed for semiconductor industry enabled then the fabrication of Fresnel zone plates (FZP), which are now commonly used for focusing x-rays, notably in x-ray microscopes, but also for other future advanced characterization tools, such as nano-Angle Resolved PhotoEmission Spectroscopy (n-ARPES) [40]. FZPs are circular diffraction gratings with a wavelength dependent focus length.…”