Laser ablation of polysulfone films: a laser ionization TOF mass spectrometric study

We have applied laser ionization time-of-flight (TOF) mass spectrometry to ablation of polysulfone (PS) with 266 nm laser light at fluences of 20-60 mJ/cm(2). Major peaks were assigned to direct fragments and recombination products ejected from the PS surface. The arrival profiles of these ablation products varied from product to product and were fitted by using a shifted Maxwell-Boltzmann distribution with a center-of-mass flight velocity [(1.4 - 5.6) x 10(5) cm/s] and a Knudsen layer temperature (350-3810 K). Two types of ablation products, whose velocities and temperatures showed different dependences on laser fluence, were found to exist. Dynamical aspects in the decomposition of the polymer chain, the ejection of various fragments, and their expansion are discussed on the basis of a photothermal ablation model, where a heated surface layer with a temperature gradient along its depth plays an important role.