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Article History

Received: 8 February 2016

Accepted: 25 May 2016

First Online: 27 June 2016

Change Date: 30 September 2016

Change Type: Corrigendum

Change Details: In the version of this Letter originally published, in the Acknowledgements section, the descriptions of the funding sources for STM measurement and instrumentation and graphene characterization were incorrect and should have read: 'This research was supported by the sp2 program (KC2207) (STM measurement and instrumentation) funded by the Director, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division, of the US Department of Energy under Contract No. DE-AC02-05CH11231. For the graphene characterization we used the Molecular Foundry at LBNL, which is funded by the Director, Office of Science, Office of Basic Energy Sciences, Scientific User Facilities Division, of the US Department of Energy under Contract No. DE-AC02-05CH11231.' This has now been corrected in all versions of the Letter.

Competing interests

: The authors declare no competing financial interests.