Reaction Pathway toward Seven-Atom-Wide Armchair Graphene Nanoribbon Formation and Identification of Intermediate Species on Au(111)

Thussing, Sebastian; Flade, Sebastian; Eimre, Kristjan; Pignedoli, Carlo A.; Fasel, Roman; Jakob, Peter (2020). Reaction Pathway toward Seven-Atom-Wide Armchair Graphene Nanoribbon Formation and Identification of Intermediate Species on Au(111). Journal of physical chemistry. C, 124(29), pp. 16009-16018. American Chemical Society 10.1021/acs.jpcc.0c04596

Preview	Text Postprint_Thussing.pdf - Accepted Version Available under License Publisher holds Copyright. Download (9MB) | Preview
	Text acs.jpcc.0c04596.pdf - Published Version Restricted to registered users only Available under License Publisher holds Copyright. Download (3MB)

The prototypical surface reaction of 10,10'-dibromo-9,9'-bianthryl (DBBA) towards the 7-atom-wide armchair graphene nanoribbon (7-AGNR) on the Au(111) surface has been investigated by means of vibrational spectroscopy, thermal desorption spectroscopy and density functional theory. Specifically, a direct correlation between annealing temperature and the formation of various intermediate species is derived. By comparing IR spectra with results from DFT calculations an identification of reaction intermediates has been achieved, allowing for a precise mapping of individual reaction steps. Thereby, we identify a prior unknown partially dehalogenated and strongly tilted DBBA* mono-radical species (DBBA-1Br) after mild annealing (380-450 K). This inclined adsorption geometry stabilizes the second Br atom, preventing full dehalogenation. According to our calculations dimerization of DBBA-1Br reverses this inclination and provides an efficient way to enable abstraction of the second Br atom and initiate polyanthracene chain formation by means of DBBA* addition. As a competitive process to dimerization a minor amount of the DBBA* mono-radicals recombine with previously released bromine atoms leading to associative DBBA desorption. In the course of thermal processing hydrogen release signals planarization of the twisted anthracene units of DBBA by means of cyclodehydrogenation and formation of the final 7-AGNR. Based on the results of this work an in-depth understanding of the on-surface synthesis of 7-AGNR on Au(111), starting with a DBBA molecular precursor, has been attained.

Interest & Impact

Downloads

208 since deposited on 03 Sep 2020
36 in the past 12 months

Citations

5 Citations in Web of Science ®
6 Citations in Scopus

Search

in Google Scholar™

Services

Actions (login required)

Edit item

Actions (login required)

Edit item