Spatio-temporal dynamics of anisotropic emission from nano second laser produced aluminium plasma

TL;DR

This study investigates the spatio-temporal behavior of emission anisotropy and polarization in nanosecond laser-produced aluminium plasma, revealing how charge states and magnetic fields influence emission properties over space and time.

Contribution

It provides new insights into the spatio-temporal evolution of emission anisotropy and polarization in laser-produced plasma, highlighting the role of atomic processes and magnetic fields.

Findings

Degree of polarization reverses sign along plume propagation

Magnetic field effects are significant near the sample but diminish with distance

Emission anisotropy depends on charge state and atomic processes

Abstract

Polarized emission carries captivating information and can help understand various elementary processes involving collisions within the plasma as well as in radiative transitions. In this work, we investigate the spatio-temporal dependence of the emission anisotropy of a nanosecond laser produced aluminium plasma at 100 mbar background pressure. We observe that the anisotropy of the emission spectra exhibits interesting spatio-temporal characteristics which in turn depend on the charge state of the emitting species. The degree of polarization (DOP) is found to reverse its sign along the plume propagation direction. Observed behaviour in DOP appears to be due to the contribution from various involved atomic processes. However, closer to the sample the contribution from the self-generated magnetic field predominantly affect the polarization. On the other hand, the effect of the self generated magnetic field on the observed polarized emission is insignificant as the plume propagates away from the sample. This is of particular interest in polarization resolved laser induced breakdown spectroscopy as spatio-temporal profile of the degree of polarization has to be properly taken into account prior to the spectral analysis.