Application of iterative phase-retrieval algorithms to ARPES orbital tomography

TL;DR

This paper introduces a robust iterative phase-retrieval algorithm for reconstructing molecular orbitals from ARPES data, drawing analogies with optical diffraction imaging and successfully applying it to both optical and electronic structures.

Contribution

It presents a generalized phase-retrieval approach for ARPES orbital tomography, eliminating the need for prior shape information and enhancing reconstruction robustness.

Findings

Successful reconstruction of molecular orbitals without prior shape knowledge

Analogous optical experiments validate the phase-retrieval method

Improved robustness over previous iterative algorithms

Abstract

Electronic wave functions of planar molecules can be reconstructed via inverse Fourier transform of angle-resolved photoelectron spectroscopy (ARPES) data, provided the phase of the electron wave in the detector plane is known. Since the recorded intensity is proportional to the absolute square of the Fourier transform of the initial state wave function, information about the phase distribution is lost in the measurement. It was shown that the phase can be retrieved in some cases by iterative algorithms using a priori information about the object such as its size and symmetry. We suggest a more generalized and robust approach for the reconstruction of molecular orbitals based on state-of-the-art phase-retrieval algorithms currently used in coherent diffraction imaging. We draw an analogy between the phase problem in molecular orbital imaging by ARPES and of that in optical coherent diffraction imaging by performing an optical analogue experiment on micrometer-sized structures. We successfully reconstruct amplitude and phase of both the micrometer-sized objects and a molecular orbital from the optical and photoelectron far-field intensity distributions, respectively, without any prior information about the shape of the objects.