Response to "Comment on 'Emission of prompt electrons during excimer laserablation of aluminum targets'" [Appl. Phys. Lett. 76, 248 (2000)]

In a comment(1) on our recent letter,(2) Hong and Lu questioned that the sh arp peak in the time-of-flight (TOF) signal observed during laser ablation of the Al target in vacuum was due to photoelectrons produced by laser targ et interaction. In particular, they claimed that very similar signals have been observed during KrF excimer laser ablation of Cu targets in ambient ai r at a laser fluence of 9.2 J cm(-2) and with a probe placed at 0.75 and 1. 8 mm apart from the target surface. In a recent article,(3) such signals ha ve been ascribed to plasma induced electric fields at early stages of the l aser ablation process, when the emitted electrons and positive ions are in fast dynamics. We wish to point out that the analogy between the two electr ic signals is only apparent. In fact, the experimental approach by Lu and H ong(3) is based on the detection of electromagnetic signals due to the emit ting dipole formed by electrons and ions in the plume. This is realized by a tiny metal probe put nearby the target (< 1 cm). Both the r(-2) dependenc e of the signal amplitude (r being the probe distance) and the independence of the peak position on r ensure that the signal they observed was due to electromagnetic radiation. (C) 2000 American Institute of Physics. [S0003-6 951(00)00202-3].