Force and energy dissipation variations in non-contact atomic force spectroscopy on composite carbon nanotube systems

TL;DR

This study uses non-contact atomic force microscopy to investigate how encapsulating inorganic compounds inside carbon nanotubes affects force interactions and energy dissipation, revealing tunable optical and mechanical properties.

Contribution

It demonstrates how filling nanotubes alters van der Waals forces and energy dissipation, providing insights for tuning optical and interaction properties in nanotube-based systems.

Findings

Van der Waals forces decrease with Ag core filling.

Energy dissipation increases due to bond softening.

Filled and unfilled nanotubes can be distinguished by force and dissipation.

Abstract

UHV dynamic force and energy dissipation spectroscopy in non-contact atomic force microscopy were used to probe specific interactions with composite systems formed by encapsulating inorganic compounds inside single-walled carbon nanotubes. It is found that forces due to nano-scale van der Waals interaction can be made to decrease by combining an Ag core and a carbon nanotube shell in the Ag@SWNT system. This specific behaviour was attributed to a significantly different effective dielectric function compared to the individual constituents, evaluated using a simple core-shell optical model. Energy dissipation measurements showed that by filling dissipation increases, explained here by softening of C-C bonds resulting in a more deformable nanotube cage. Thus, filled and unfilled nanotubes can be discriminated based on force and dissipation measurements. These findings have two different implications for potential applications: tuning the effective optical properties and tuning the interaction force for molecular absorption by appropriately choosing the filling with respect to the nanotube.