Atomic monolayer deposition on the surface of nanotube mechanical resonators

TL;DR

This study uses nanotube mechanical resonators to investigate monolayer deposition of noble gases, revealing phase behaviors and structural arrangements at the atomic level.

Contribution

It demonstrates the use of nanotube resonators as sensitive probes for surface monolayer phases and provides experimental insights into noble gas monolayer structures.

Findings

Xe monolayers are solid and commensurate with nanotubes.

Ar and Ne monolayers behave as fluids.

Kr monolayers are tentatively identified as solid phases.

Abstract

We studied monolayers of noble gas atoms (Xe, Kr, Ar, and Ne) deposited on individual ultra- clean suspended nanotubes. For this, we recorded the resonance frequency of the mechanical motion of the nanotube, since it provides a direct measure of the coverage. The latter is the number of adsorbed atoms divided by the number of the carbon atoms of the suspended nanotube. Monolayers formed when the temperature was lowered in a constant pressure of noble gas atoms. The coverage of Xe monolayers remained constant at 1/6 over a large temperature range. This finding reveals that Xe monolayers are solid phases with a triangular atomic arrangement, and are commensurate with the underlying carbon nanotube. By comparing our measurements to theoretical calculations, we identify the phases of Ar and Ne monolayers as fluids, and we tentatively describe Kr monolayers as solid phases. These results underscore that mechanical resonators made from single nanotubes are excellent probes for surface science.