Experimental study on droplet generation during excimer laser ablation of polyethylene glycol 1000

Droplet generation during laser ablation is important from the point of vie w of the quality of films deposited by pulsed laser deposition. Dependence of the emitted droplet properties and distribution on the state of matter, viscosity and fluence was investigated experimentally. Polyethylene glycol (PEG) 1000 having relatively low melting paint (37 degreesC) was used in ou r experiments. By variation of target temperature between 23 and 80 degrees C the amount and dimensions of emitted droplets were studied. An ArF excime r laser was used for irradiation, the applied fluence was varied in the ran ge of 0.37-2.66 J/cm(2). The droplets were caught onto a quartz plate place d above the target. During the transition from solid to liquid state of PEG 1000 the number and the total volume of droplets emitted during ablation w ere drastically decreased, reaching a minimum at 40 degreesC. Further heati ng of the molten target resulted in increment in the amount of emitted drop lets, At 70 degreesC target temperature the maximum quantity of droplets we re deposited at a fluence of 1.28 J/cm(2), It was found that with increasin g viscosity the number and total volume of droplets decrease significantly. Deposition with the smallest amount of droplets is reached, when using mol ten targets near to melting point with a high viscosity. (C) 2000 Elsevier Science B.V. All rights reserved.