Formation of oxidized aluminum nanopowders by exposing aluminum to a series of double laser pulses in air

Abstract

The effects of the interval between pulses and the number of double laser pulses on the component and charge composition of the laser plasma formed by these pulses acting on an AD1 aluminum alloy target (LSS-1 spectrometer) are studied. It is shown that the concentration of Al ions and the products of their interaction with atmospheric O2 and N2 increase by several orders of magnitude if an interval between pulses of 7–16 μs rather than a zero interval is used. Formation of Al ions is studied as a function of pulse energy with an interval between pulses of 10 μs. The strongest lines for Al III ions are observed for a small number (~15) consecutive double pulses in series and a pulse energy of 53 mJ. The intensity of the lines for Al III ions decreases by about fi ve times if the number of pulses in the series increases above a certain level (10–20) because of their active interaction with atmospheric molecules and atoms at the exit of the micronozzle when the channel shape is changed. Al nanopowders coated with a layer of aluminum oxide produced by irradiating an Al target with a series of 15 double laser pulses per point have sizes of mainly 50–60 μm.