Mechanical detection of carbon nanotube resonator vibrations

TL;DR

This paper demonstrates a novel mechanical detection method for observing bending vibrations of carbon nanotube resonators at atmospheric pressure, achieving high-resolution imaging of eigenmodes up to 3.1 GHz.

Contribution

It introduces a new scanning force microscopy technique for detecting nanotube vibrations in air and analyzes the effects of fabrication-induced slack on resonance frequencies.

Findings

Resonance frequencies match elastic beam theory for multi-wall nanotubes.

Single-wall nanotubes show shifted resonance frequencies due to fabrication slack.

Pulling the nanotube reduces slack and significantly lowers resonance frequency.

Abstract

Bending-mode vibrations of carbon nanotube resonator devices were mechanically detected in air at atmospheric pressure by means of a novel scanning force microscopy method. The fundamental and higher order bending eigenmodes were imaged at up to 3.1GHz with sub-nanometer resolution in vibration amplitude. The resonance frequency and the eigenmode shape of multi-wall nanotubes are consistent with the elastic beam theory for a doubly clamped beam. For single-wall nanotubes, however, resonance frequencies are significantly shifted, which is attributed to fabrication generating, for example, slack. The effect of slack is studied by pulling down the tube with the tip, which drastically reduces the resonance frequency.