Fluence-Dependent Changes in Surface Wettability and Conductivity of Ion-Irradiated Carbon-Based Foils

TL;DR

This study shows how ion irradiation changes the surface and electrical properties of carbon-based materials in a controlled way.

Contribution

The paper demonstrates fluence-dependent modification of surface wettability and conductivity in ion-irradiated carbon-based foils.

Findings

COC substrates showed decreased water contact angle and increased surface free energy with higher ion fluence.

Graphene oxide exhibited a distinct response compared to COC in surface wettability changes.

Sheet resistivity in polymers decreased significantly with increasing ion fluence.

Abstract

The surface properties and electrical behavior of carbon-based materials can be effectively modified by energetic ion irradiation. In the present study, graphene oxide (GO) and cyclic olefin copolymer foils (COC, Topas 112 and 011, respectively) were irradiated with 1 MeV Au ions using a 3 MV Tandetron accelerator at fluences of 1 × 1014, 1 × 1015, and 2.5 × 1015 cm−2. The irradiation induced systematic modifications in surface chemistry, morphology, wettability, and electrical properties. Composition changes were investigated using Rutherford backscattering spectrometry (RBS) and elastic recoil detection analysis (ERDA), while surface morphology and roughness were characterized by atomic force microscopy (AFM). This revealed a clear fluence-dependent evolution of nanoscale topography. The vibrational characteristics were assessed through Raman spectroscopy, and the chemical composition of the surface layers was analyzed by X-ray photoelectron spectroscopy (XPS). The surface wettability was evaluated by static contact angle measurements, and surface free energy was determined using the Owens–Wendt–Rabel–Kaelble (OWRK) method. These measurements showed a consistent decrease in water contact angle and an increase in surface free energy with increasing ion fluence in the COC substrates, whereas GO exhibited a distinct response. Electrical characterization demonstrated a pronounced fluence-dependent decrease in sheet resistivity in polymers. The results show that 1 MeV Au ion irradiation enables systematic and fluence-dependent modification of both surface and electrical properties.

Figures