Temperature Dependent Self-Assembly of 9,10-dibromo-anthracene on Ag(111)

Thin film growth of 9,10-dibromo-anthracene (DBA) on Ag(111) up to a full monolayer has been studied via UHV scanning tunneling microscopy (STM). Prior studies of thin film growth for deposition of this molecule on the same substrate while at room temperature has demonstrated debromination of the molecule followed by self-assembly of a chain-like structure mediated by Ag adatoms [1]. However, our results show no debromination and instead a honeycomb network is formed. The reason for this discrepancy is still under investigation, with present studies focused on accurately cataloguing substrate temperature during film growth. We note that other STM studies of brominated organic molecules grown at reduced substrate temperatures have shown debromination of those molecules only upon subsequent annealing of the film [2]. A molecular model of our film growth will be presented, with the organization of the film most likely driven by weak bromine-bromine bonding between adjacent molecules.

References:

[1] J. Park, K.Y. Kim, K.-H. Chung, J.K. Yoon, H. Kim, S. Han, and S.-. Kahng, J. Phys. Chem. C 115, 14835 (2011).

[2] J. Liu, Q. Chen, Q. He, Y. Zhang, X. Fu, Y. Wang, D. Zhao, W. Chen, G.Q. Xu, and K. Wu, Phys. Chem. Chem. Phys. 20, 11081 (2018).