Assessing and ameliorating the influence of the electron beam on carbon nanotube oxidation in environmental transmission electron microscopy

In this work, we examine how the imaging electron beam can induce damage in carbon nanotubes (CNTs) at varying oxygen gas pressures and electron dose rates using environmental transmission electron microscopy (ETEM). Our studies show that there is a threshold cumulative electron dose which brings about damage in CNTs in oxygen – through removal of their graphitic walls – which is dependent on O₂ pressure, with a 4–5 fold decrease in total electron dose per decade increase at a lower pressure range (10⁻⁶ to 10⁻⁵ mbar) and approximately 1.3 –fold decrease per decade increase at a higher pressure range (10⁻³ to 10⁰ mbar). However, at a given pressure, damage in CNTs was found to occur even at the lowest dose rate utilized, suggesting the absence of a lower limit for the latter parameter. This study provides guidelines on the cumulative dose required to damage nanotubes in the 10⁻⁷ mbar to 10⁰ mbar pressure regimes, and discusses the role of electron dose rate and total electron dose on beam-induced CNT degradation experiments. - Highlights: • The electron beam ionizes gas molecules in ETEM and affects experimental outcomes. • Beam-induced damage in CNTs occurs at varying O₂ pressures and electron dose rates. • There is a threshold cumulative dose to damage CNTs which depends on O₂ pressure. • At a given pressure, CNT damage occurs even at the electron dose rate utilized.