Stable $\pi$-radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) adsorbed at the elbows of $22\times\sqrt{3}$ reconstructed Au(111)

TL;DR

This study uses low-temperature STM to analyze the structure and electronic properties of a stable organic radical, DPPH, adsorbed on a reconstructed gold surface, revealing preserved spin states and detailed molecular interactions.

Contribution

It provides the first detailed single-molecule analysis of DPPH radicals on Au(111), highlighting their structural and electronic characteristics at the atomic level.

Findings

DPPH radicals maintain their unpaired electron spin state on Au(111).

STM reveals detailed structural and electronic features of DPPH on the surface.

A Kondo-like signature indicates preserved magnetic properties.

Abstract

Stable organic radicals serve as model systems for investigating metal-free magnetic phenomena at (sub)nanometer length scales. We have investigated at the single-molecule level the stable $\pi$-radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) adsorbed at the elbow sites of the $22\times\sqrt{3}$ reconstructed Au(111) surface. Low-temperature scanning tunneling microscopy (STM) and -spectroscopy under ultrahigh vacuum conditions at 8~K reveal structural as well as frontier-orbital related electronic details of DPPH/Au(111). A Kondo-like spectroscopic signature indicates preservation of the unpaired electron spin state.