| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1239415 | Spectrochimica Acta Part B: Atomic Spectroscopy | 2016 | 9 Pages |
•Influence of laser beam profile on double pulse LIBS was studied for the first time•Double pulse enhancement was observed to depend on chosen laser beam profile•Spectral lines intensities and background emission depend on chosen laser beam profile (Guassian or multimode)
Single vs multimode laser beams were compared for double pulse laser ablation, plasma properties and laser induced breakdown spectroscopy (LIBS) analytical capabilities. Laser beams with Gaussian and multimode profiles were generated within the same Nd:YAG laser in single and double pulse regimes. Gaussian beam produced a small and deep crater while multimode beam formed a wide shallow crater. Greater double pulse enhancement of ablated material and plasma volume were observed for Gaussian beam sampling. The higher intensity for atomic/ionic lines in the plasma spectra was observed for multimode beam sampling due to greater laser pulse energy and larger ablated mass. Interestingly, spectra line intensity enhancement for double pulse ablation was 2–3 times greater for Gaussian than for multimode beam ablation. Background emission decreased for plasma induced by multimode beam when using double pulse mode while for Gaussian beam an opposite dependence was observed. Surprisingly, higher peak fluence at sample surface for Gaussian beam didn't provide higher plasma temperature and electron density for double pulse ablation. Analytical capabilities of LIBS method were compared for double pulse plasma induced by Gaussian and multimode beam in terms of precision, sensitivity and linearity of calibration curves. It was observed that Gaussian beam sampling leads to improvement of analysis precision while sensitivity was element dependent.
