Ablation yield and angular distribution of ablated particles from laser-irradiated metals: The most fundamental determining factor |
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Authors: | Dilawar AliMZ Butt M Khaleeq-ur-Rahman |
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Institution: | Department of Physics, University of Engineering and Technology, G.T. Road, Lahore 54890, Pakistan |
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Abstract: | Five metals (Zn, Cu, Ni, Ti, and Mo) were irradiated with 150 shots of a Q-switched Nd:YAG pulsed laser in a vacuum of 10−3 torr. The ions projected out of the laser-produced plasma (LPP) plume were detected by CR-39 detectors positioned at −15°, 0°, 30°, 60°, and 90° with respect to the target-surface normal at a distance of 5 cm from the target in each case. The angular distribution of LPP ions, which is characterized by the exponent n of cosn θ distribution, is given by n = 2.5-11 for the five target metals. The value of the exponent n has no systematic correlation with the square-root of atomic mass of the target metals but exhibits systematic dependence on the room temperature Debye-Waller's thermal parameter B or the mean-square amplitude of atomic vibrations 〈u2〉. Likewise, the ablation yield (atoms/shot) of the twelve target metals investigated by Thestrup et al. (2002) 8] under identical irradiation conditions is a function of the room temperature B-factor or 〈u2〉. |
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Keywords: | Nd:YAG laser Ablation yield Angular distribution Sublimation energy Debye-Waller's thermal parameter |
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