Protein Electronic Energy Transport Levels Derived from High-Sensitivity Near-UV and Constant Final State Yield Photoemission Spectroscopy

26 August 2024, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Proteins are attractive as functional components in molecular junctions. However, control-ling the electronic charge transport via proteins, held between two electrodes, requires in-formation on their frontier orbital energy level alignment relative to the electrodes’ Fermi level (EF), which normally requires studies of UV Photoemission Spectroscopy (UPS) with HeI excitation. Such excitation is problematic for proteins, which can denature under stand-ard measuring conditions. Here we use high-sensitivity soft UV photoemission spectroscopy (HS-UPS) combined with Constant Final State Yield Spectroscopy (CFS-YS) to get this in-formation for electrode/protein contacts. Monolayers of the redox protein Azurin, (Az) and its Apo-form on Au substrates, have HOMO onset energies, obtained from CFS-YS, differ by ~ 0.2 eV, showing crucial role of the Cu redox centre in the electron transport process. We find that combined HS-UPS / CFS-YS measurements agree with the Photoelectron Yield Spectroscopy (PYS), showing potential of the HS-UPS + CFS-YS as a powerful tool to char-acterize and map the energetics of a protein-electrode interfaces, which will aid optimizing design of devices with targeted electronic properties, as well as for novel applications.

Keywords

Photoemission spectroscopy
Bio-electronics
Protein-electrode interfaces
Constant Final State Yield Spectroscopy and Protein energetics

Supplementary materials

Title
Description
Actions
Title
Supporting Information
Description
Supporting information for the main manuscript
Actions

Comments

Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.