Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5369902 | Applied Surface Science | 2006 | 7 Pages |
A free-running Er:YAG laser is used to ablate polyethylene glycol and the ablation yield is studied as a function of molecular weight (1000-10,000Â g/mol) and laser fluence (8-25Â J/cm2). A steady-state ablation mechanism is proposed which includes recoil-induced expulsion as the primary contributor to the ablation yield. It is also proposed that the formation of a molten layer is a necessary part of the ablation mechanism because the calculated tensile strengths for the solid polymer are too large to permit fracture of the target due to the laser-induced stress transient. The ablation yield is found to depend in a sigmoidal fashion upon laser fluence, thus implying a variable ablation enthalpy. Finally, the current results are compared with that obtained previously with a free electron laser.