6 research outputs found
Multi-modal identification of leakage-induced acoustic vibration in gas-filled pipelines by selection of coherent frequency band
Polymer Adsorption on Graphite and CVD Graphene Surfaces Studied by Surface-Specific Vibrational Spectroscopy
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 PEÂ(HÂ(CH<sub>2</sub>CH<sub>2</sub>)<sub>n</sub>H) with <i>n</i> ≈ 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