title: Polymer Adsorption on Graphite and CVD Graphene Surfaces Studied by Surface-Specific Vibrational Spectroscopy.
abstract: Sum-frequency vibrational spectroscopy was employed to probe polymer contaminants on chemical vapor deposition (CVD) graphene and to study alkane and polyethylene (PE) adsorption on graphite. In comparing the spectra from the two surfaces, it was found that the contaminants on CVD graphene must be long-chain alkane or PE-like molecules. PE adsorption from solution on the honeycomb surface results in a self-assembled ordered monolayer with the C-C skeleton plane perpendicular to the surface and an adsorption free energy of ∼42 kJ/mol for PE(H(CH2CH2)nH) with n ≈ 60. Such large adsorption energy is responsible for the easy contamination of CVD graphene by impurity in the polymer during standard transfer processes. Contamination can be minimized with the use of purified polymers free of PE-like impurities.
authors.affiliation: State Key Laboratory of Surface Physics and Department of Physics, Fudan University , Shanghai 200433, China.|Collaborative Innovation Center of Advanced Microstructures, Fudan University , Shanghai 200433, China.
authors.forename: Yudan
authors.initials: Y
authors.lastname: Su
authors.affiliation: Department of Physics, University of California , Berkeley, California 94720, United States.
authors.forename: Hui-Ling
authors.initials: HL
authors.lastname: Han
authors.affiliation: State Key Laboratory of Surface Physics and Department of Physics, Fudan University , Shanghai 200433, China.
authors.forename: Qun
authors.initials: Q
authors.lastname: Cai
authors.affiliation: State Key Laboratory of Surface Physics and Department of Physics, Fudan University , Shanghai 200433, China.|Collaborative Innovation Center of Advanced Microstructures, Fudan University , Shanghai 200433, China.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Molecular Engineering of Polymers and Department of Macromolecular Science, Fudan University , Shanghai 200433, China.
authors.forename: Mingxiu
authors.initials: M
authors.lastname: Xie
authors.affiliation: State Key Laboratory of Molecular Engineering of Polymers and Department of Macromolecular Science, Fudan University , Shanghai 200433, China.
authors.forename: Daoyong
authors.initials: D
authors.lastname: Chen
authors.affiliation: Department of Physics, University of California , Berkeley, California 94720, United States.|School of Physical Science and Technology, Lanzhou University , Lanzhou 730000, China.
authors.forename: Baisong
authors.initials: B
authors.lastname: Geng
authors.affiliation: State Key Laboratory of Surface Physics and Department of Physics, Fudan University , Shanghai 200433, China.|Collaborative Innovation Center of Advanced Microstructures, Fudan University , Shanghai 200433, China.
authors.forename: Yuanbo
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Physics, University of California , Berkeley, California 94720, United States.
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Surface Physics and Department of Physics, Fudan University , Shanghai 200433, China.|Department of Physics, University of California , Berkeley, California 94720, United States.
authors.forename: Y R
authors.initials: YR
authors.lastname: Shen
authors.affiliation: State Key Laboratory of Surface Physics and Department of Physics, Fudan University , Shanghai 200433, China.|Collaborative Innovation Center of Advanced Microstructures, Fudan University , Shanghai 200433, China.
authors.forename: Chuanshan
authors.initials: C
authors.lastname: Tian
keywords: CVD graphene; graphite; self-assembled alkane; sum frequency vibrational spectroscopy; surface residue; surface structure