KrF laser ablation of a polyethersulfone film: Effect of pulse duration on structure formation

Polyethersulfone (PES) films were processed with KrF laser irradiation of different pulse durations (τ). Scanning electron microscopy (SEM) and Raman spectroscopy were employed for the examination of the morphology and chemical composition of the irradiated surfaces, respectively. During ablation with 500 fs and 5 ps pulses, localized deformations (beads), micro-ripple and conical structures were observed on the surface depending on the irradiation fluence (F) and the number of pulses (N). In addition, the number density of the structures is affected by the irradiation parameters (τ, F, N). Furthermore, at longer pulse durations (τ = 30 ns), conical structures appear at lower laser fluence values, which are converted into columnar structures upon irradiation at higher fluences. The Raman spectra collected from the top of the structures following irradiation at different pulse durations revealed graphitization of the ns laser treated areas, in contrast to those processed with ultra-short laser pulses.

► The early stages of structure formation on polyethersulfone (PES) surface following KrF laser irradiation depend on the pulse duration. ► The number density of the cones increases with number of pulses in the ns case while it decreases upon ultra-short pulse (fs and ps) irradiation. ► The chemical compositions induced in the laser treated surfaces depend on pulse duration. ► Control of PES surface morphology upon KrF laser irradiation can be attained by proper combination of pulse duration and number of pulses.