Insights into radiation damage from atomic resolution scanning transmission electron microscopy imaging of mono-layer CuPcCl16 films on graphene

Andreas Mittelberger,Christian Kramberger,Jannik C Meyer

doi:10.1038/s41598-018-23077-z

Andreas Mittelberger, Christian Kramberger + Show 1 more

Open Access

https://doi.org/10.1038/s41598-018-23077-z

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Journal: Scientific Reports	Publication Date: Mar 19, 2018
Citations: 21	License type: open-access

Affiliation: University of Vienna

Abstract

Atomically resolved images of monolayer organic crystals have only been obtained with scanning probe methods so far. On the one hand, they are usually prepared on surfaces of bulk materials, which are not accessible by (scanning) transmission electron microscopy. On the other hand, the critical electron dose of a monolayer organic crystal is orders of magnitudes lower than the one for bulk crystals, making (scanning) transmission electron microscopy characterization very challenging. In this work we present an atomically resolved study on the dynamics of a monolayer CuPcCl16 crystal under the electron beam as well as an image of the undamaged molecules obtained by low-dose electron microscopy. The results show the dynamics and the radiation damage mechanisms in the 2D layer of this material, complementing what has been found for bulk crystals in earlier studies. Furthermore, being able to image the undamaged molecular crystal allows the characterization of new composites consisting of 2D materials and organic molecules.

Highlights

Phtalocyanines (Pc), and in particular Copper-Phtalocyanine (CuPc), have attracted great interest in surface science and microscopy, both as an active material[1,2,3,4,5] and as a model system
The samples were prepared by evaporating CuPcCl16 powder purchased from Sigma Aldrich (Phtalocyanine green) onto monolayer graphene on transmission electron microscope (TEM) grids (Graphenea)
Individual molecules are highly mobile on these surfaces and can only be imaged at very low temperatures (e.g. 35 K)[21,22]

Summary

Introduction

Phtalocyanines (Pc), and in particular Copper-Phtalocyanine (CuPc), have attracted great interest in surface science and microscopy, both as an active material[1,2,3,4,5] and as a model system. Translational averaging was done by cutting the raw image into small subframes, each containing one unit cell of the CuPcCl16 crystal lattice. Where the imaging dose was already high enough to damage the molecules and the film is slowly removed, there is no intermediate gray level between a full coverage and the clean graphene.

Results

Conclusion