Synergistic Formation of Radicals by Irradiation with Both Vacuum Ultraviolet and Atomic Hydrogen: A Real-Time In Situ Electron Spin Resonance Study

TL;DR

This study demonstrates that simultaneous irradiation with vacuum ultraviolet and atomic hydrogen synergistically enhances radical formation on PTFE surfaces, using real-time ESR measurements to analyze the process.

Contribution

It introduces an in situ real-time ESR method to investigate synergistic radical formation during plasma surface modification.

Findings

C-DB density increases during irradiation, with an initial rapid change.

Synergistic radical formation occurs only when both VUV and atomic hydrogen are used.

Real-time ESR effectively elucidates plasma-surface interaction dynamics.

Abstract

We report on the surface modification of polytetrafluoroethylene (PTFE) as an example of soft- and bio-materials that occur under plasma discharge by kinetics analysis of radical formation using in situ real-time electron spin resonance (ESR) measurements. During irradiation with hydrogen plasma, simultaneous measurements of the gas-phase ESR signals of atomic hydrogen and the carbon dangling bond (C-DB) on PTFE were performed. Dynamic changes of the C-DB density were observed in real time, where the rate of density change was accelerated during initial irradiation and then became constant over time. It is noteworthy that C-DBs were formed synergistically by irradiation with both vacuum ultraviolet (VUV) and atomic hydrogen. The in situ real-time ESR technique is useful to elucidate synergistic roles during plasma surface modification.