On acoustical registration of irradiated surface displacement during nanosecond laser-metal interaction and metal–nonmetal transition effect

On metal-dielectric transition in laser ablation modeling

“…Behavior of the kind may be related to the metal-dielectric transition [5][6][7][8][9][10] when its front moves deeply into the irradiated target. The transition modeling in [8] for supposed metaldielectric transition in Al shows additional bump in the pressure curve which is visible also in [11] at intensities  50 MW/cm 2 .…”

“…In ref. [11] pressure behavior in liquid mercury is investigated during irradiation with different laser pulses: a train of several subnanosecond laser peaks divided with 8 ns intervals and a single 30 ns relatively smooth laser pulse. Using intensity modulated laser pulses permits to obtain information about irradiated surface displacement as it was first demonstrated in [15] for the case of dielectric liquids irradiated with harmonically modulated laser pulses.…”

“…It is shown in [11] that the pressure response detected with piezoelectric transducers as well as the surface displacement can not be explained in the framework of surface metal evaporation. In particular, significant diminishing  of the acoustical arrival time is observed which means that the laser absorption zone deepens into the target for far more distance h = v s , v ssound velocity, than it is the case for metal ablation where h m ~ α m -1 .…”

“…In the present paper possible manifestations of this transition for mercury are analyzed in the framework of simplified one-dimensional approach using the previous results [7,8] and recent experimental investigation [11].…”

“…For this reason, further theoretical and experimental investigations of intense laser-metal interaction are necessary including the possibility of metal-dielectric transition which is also discussed in many papers (see e.g. [4][5][6][7][8][9][10][11] and references therein).…”