Casimir-Polder interaction of fullerene molecules with surfaces

TL;DR

This paper calculates the thermal Casimir-Polder potential for fullerene molecules near surfaces, revealing the dominant electronic transition effects and how molecular line widths influence the interaction, with implications for molecular interference experiments.

Contribution

It provides detailed calculations of the Casimir-Polder potential for fullerenes, including asymptotic behaviors and the impact of molecular line widths, advancing understanding of molecule-surface interactions.

Findings

Electronic transitions dominate the interaction.

Molecular temperature has minimal effect on the potential.

Line widths can modify the nonretarded interaction depending on the model.

Abstract

We calculate the thermal Casimir--Polder potential of C60 and C70 fullerene molecules near gold and silicon nitride surfaces, motivated by their relevance for molecular matter wave interference experiments. We obtain the coefficients governing the asymptotic power laws of the interaction in the thermal, retarded and nonretarded distance regimes and evaluate the full potential numerically. The interaction is found to be dominated by electronic transitions, and hence independent of the internal temperature of the molecules. The contributions from phonon transitions, which are affected by the molecular temperature, give rise to only a small correction. Moreover, we find that the sizeable molecular line widths of thermal fullerenes may modify the nonretarded interaction, depending on the model used. Detailed measurements of the nonretarded potential of fullerene thus allow one to distinguish between different theories of incorporating damping.