Experimental setup for low-energy laser-based angle resolved photoemission spectroscopy

TL;DR

This paper describes a laser-based ARPES system using 6 eV photons that enhances momentum resolution, increases photoelectron count, and reduces background, with detailed optical setup and calibration procedures, applied to high T_c superconductor Bi2212.

Contribution

It introduces a low-energy laser-based ARPES setup with improved resolution and efficiency, including calibration and experimental considerations, applied to a well-studied superconductor.

Findings

Enhanced momentum resolution and photoelectron count rate.

Reduced extrinsic background and surface sensitivity.

Comparable data quality to higher photon energy ARPES.

Abstract

A laser-based angle resolved photoemission (APRES) system utilizing 6 eV photons from the fourth harmonic of a mode-locked Ti:sapphire oscillator is described. This light source greatly increases the momentum resolution and photoelectron count rate, while reducing extrinsic background and surface sensitivity relative to higher energy light sources. In this review, the optical system is described, and special experimental considerations for low-energy ARPES are discussed. The calibration of the hemispherical electron analyzer for good low-energy angle-mode performance is also described. Finally, data from the heavily studied high T_c superconductor Bi2Sr2CaCu2O8+\delta (Bi2212) is compared to the results from higher photon energies.