Table-top three-dimensional photoemission orbital tomography with a femtosecond extreme ultraviolet light source

TL;DR

This paper presents a novel table-top ultrafast 3D photoemission orbital tomography method using a femtosecond extreme ultraviolet source, enabling detailed imaging of molecular orbitals with high spatial and temporal resolution.

Contribution

It introduces an integrated experimental and algorithmic approach for rapid 3D orbital imaging, reducing data acquisition time and sampling requirements.

Findings

Successful 3D imaging of organic semiconductor orbitals

Enhanced speed and efficiency in orbital tomography

Demonstrated capability with a prototypical organic molecule

Abstract

Following electronic processes in molecules and materials at the level of the quantum mechanical electron wavefunction with angstrom-level spatial resolution and with full access to its femtosecond temporal dynamics is at the heart of ultrafast condensed matter physics. A breakthrough invention allowing experimental access to electron wavefunctions was the reconstruction of molecular orbitals from angle-resolved photoelectron spectroscopy data in 2009, termed photoemission orbital tomography (POT). This invention puts ultrafast three-dimensional (3D) POT in reach, with many new prospects for the study of ultrafast light-matter interaction, femtochemistry and photo-induced phase transitions. Here, we develop a synergistic experimental-algorithmic approach to realize the first 3D-POT experiment using a short-pulse extreme ultraviolet light source. We combine a new variant of photoelectron spectroscopy, namely ultrafast momentum microscopy, with a table-top spectrally-tunable high-harmonic generation light source and a tailored algorithm for efficient 3D reconstruction from sparse, undersampled data. This combination dramatically speeds up the experimental data acquisition, while at the same time reducing the sampling requirements to achieve complete 3D information. We demonstrate the power of this approach by full 3D imaging of the frontier orbitals of a prototypical organic semiconductor absorbed on pristine Ag(110).