Nanoscale X-ray investigation of magnetic metallofullerene peapods

TL;DR

This paper demonstrates advanced nanoscale X-ray techniques to analyze the structure and magnetic properties of lanthanide ions encapsulated inside carbon nanotubes, revealing preserved magnetic behavior and enabling local magnetic characterization.

Contribution

It introduces a combined microscopy and X-ray spectroscopy approach for nanoscale analysis of magnetic lanthanide ions within carbon nanotubes, showing preserved magnetic properties.

Findings

Structures down to 30 nm are resolved with chemical contrast.

X-ray absorption spectra from individual nanoscale CNT bundles are recorded.

Magnetic properties of Er3+ ions remain unchanged when encapsulated.

Abstract

Endohedral lanthanide ions packed inside carbon nanotubes (CNTs) in a one-dimensional assembly have been studied with a combination of high resolution transmission electron microscopy (HRTEM), scanning transmission X-ray microscopy (STXM), and X-ray magnetic circular dichroism (XMCD). By correlating HRTEM and STXM images we show that structures down to 30 nm are resolved with chemical contrast and record X-ray absorption spectra from endohedral lanthanide ions embedded in individual nanoscale CNT bundles. XMCD measurements of an Er$_3$N@C$_{80}$ bulk sample and a macroscopic assembly of filled CNTs indicates that the magnetic properties of the endohedral Er3+ ions are unchanged when encapsulated in CNTs. This study demonstrates the feasibility of local magnetic X-ray characterization of low concentrations of lanthanide ions embedded in molecular nanostructures.