Cairo University

MTPR Journal

 

Laser Induced Plasma Spectroscopy of Nano vs. Bulk Materials

& doi:
A. M. EL Sherbini

In this work, we present recent results on behavior of nanoparticles when irradiated with Nd: YAG laser pulses. The light emitted from plasma generated with a set of nanomaterial and bulk targets (ZnO, Fe3O4, Ag2O, TiO2, SiO2 and Al2O3) is compared for the same experimental conditions. The laser fluence was detuned in the range from 86 J/cm2 down to 2.5 J/cm2 with special emphasizes on the Ag2O nanomaterial. The targets are irradiated with nanosecond, pulsed Nd: YAG laser radiation, at 1064 nm in laboratory air. The spectra were recorded at the gate and time delay of 1 μs and for a constant spot size of 0.9 mm. The results show an exponential increase in the enhanced emissions with decrease of the laser fluence. The reversed behavior is discussed here. On the other hand, the laser fluence was kept at a constant level while the delay was changed in equal steps of 1 μs. The measurement of plasma parameters when utilizing optical emission spectroscopy technique reveals no significant variation of the relative electron density and temperature with laser fluence or delay time. The variation of the relative concentration with laser fluence, after correcting the measured spectral lines for self-absorption, attests that the enhanced emission can be attributed only to the relative concentrations. Possible explanations are based on changes in the physical properties of the nanomaterial upon subjected to high power laser pulses.