Transient pressure induced by laser ablation of toluene, a highly laser-absorbing liquid

Transient processes of laser ablation of a highly laser-absorbing liquid, toluene, were investigated by directly measuring (by using a fast-response pressure gauge) the transient pressure caused by toluene ablation under KrF laser irradiation . The results were compared with time-resolved images . The peak pressure P due to a shock wave decreased slowly with increasing distance d for d=100–1000 m:Pd^-0.33. By extrapolating P to d=8.9 m, the optical penetration depth of toluene at =248 nm, the estimated initial pressure due to toluene ablation was 65 MPa at 1.0 J cm^-2 pulse^-1. The estimated initial pressure increased linearly with the fluence. These results help clarify the mechanism of laser-induced backside wet etching. PACS 79.20.Ds; 47.40.Nm; 47.55.Bx; 81.65.Cf