Ofcourse it can be seen.. but keep the operating voltage low else it will rupture graphene sheet.

Thanks for responding. Can you give any refrence of paper?

Take a look at

http://onlinelibrary.wiley.com/doi/10.1002/ange.200902365/full

http://www.sciencedirect.com/science/article/pii/S003810980700316X

Do not make accent on lower voltages: in TEM lower voltage usually means more beam damage. From other side low voltage may give higher contrast (but lower resolution also).

take a look. Even the dynamic behaviour of graphen under the beam can be observed in low voltage HRTEM

http://www.salve-project.de/press/dislocation_3d_buckling_news.pdf

http://www.salve-project.de/newspress/formation-of-fullerenes-out-of-graphene.html

http://www.salve-project.de/newspress/formation-of-linear-carbon-chains.html

Bert