title: Excitation wavelength dependent fluorescence of graphene oxide controlled by strain.
abstract: Unlike conventional fluorophores, the fluorescence emission of graphene oxide (GO) sheets can shift hundreds of nanometers as the excitation wavelength increases. The excitation wavelength dependent fluorescence is referred to as a giant red-edge effect and originates in a local reorganization potential slowing down the solvation dynamics of the excited state to the same time scale as the fluorescence lifetime. The present work has discovered that out-of-plane strain in the graphene oxide sheet leads to the intra-layer interaction necessary to slow down the solvation time scale. The oxygen percentage, dopant percentage, disorder, and strain are correlated with the presence and extent of the red-edge effect in oxygen, boron, nitrogen, and fluorine doped graphene oxide. Of these commonly cited possibilities, only out-of-plane strain is directly correlated to the red-edge effect. Furthermore, it is shown that the extent of the red-edge effect, or how far the emission wavelength can shift with increasing excitation wavelength, can be tuned by the electronegativity of the dopant. The present work interprets why the giant red-edge effect is present in some GO sheets but not in other GO sheets.
authors.affiliation: Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26506-6106, USA. nick.wu@mail.wvu.edu and Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506-6315, USA.
authors.forename: Scott K
authors.initials: SK
authors.lastname: Cushing
authors.affiliation: Department of Industrial and Management Systems Engineering, West Virginia University, Morgantown, WV 26506-6070, USA.
authors.forename: Weiqiang
authors.initials: W
authors.lastname: Ding
authors.affiliation: Department of Physics and Astronomy, Ohio University, Athens, OH 45701, USA.
authors.forename: Gang
authors.initials: G
authors.lastname: Chen
authors.affiliation: Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, P. R. China. huangfq@mail.sic.ac.cn.
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Industrial and Management Systems Engineering, West Virginia University, Morgantown, WV 26506-6070, USA.
authors.forename: Feng
authors.initials: F
authors.lastname: Yang
authors.affiliation: Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, P. R. China. huangfq@mail.sic.ac.cn.
authors.forename: Fuqiang
authors.identifier: http://orcid.org/0000-0001-7727-0488
authors.initials: F
authors.lastname: Huang
authors.affiliation: Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26506-6106, USA. nick.wu@mail.wvu.edu.
authors.forename: Nianqiang
authors.identifier: http://orcid.org/0000-0002-8888-2444
authors.initials: N
authors.lastname: Wu