Optimize of LIBS Setup to the Determination of Laser Breakdown Power of Writing Inks

Hussam S Sadam ,Sami A Habana ,Alaa H Ali

doi:10.7176/cper/61-05

Abstract

Laser-induced breakdown spectroscopy system (LIBS) had been designed to the determinate of the best ionization laser power for analysis of the writing inks via analysis induced plasma emission. Passively Q-Switched Nd:YAG laser at the fundamental wavelength 1064 nm with different energies (60 mJ,80mJ, 100 mJ, 200 mJ, 300mJ, 400mJ and 500 mJ) with (10 ns) pulse duration, the laser beam was focused via converging lens with focal length (100 mm) that generates different power intensity, optical spectrum analysis system used was within (Si-CCD) array detector, within spectrum range of (200 - 900 nm) with (0.8 nm) optical resolution. Use A4 sheets of commercially available standard white office paper with 2 Ballpoint pens and 1 Gel pen as samples. Show the results that the laser energy (80 mJ) with ( power density, was the best power to generate plasma homogeneous for all component writing inks and ionize it without effect on the paper material. Keywords: LIBS, Laser intensity, Writing inks, White paper, plasma emissions lines, emission line analyses DOI : 10.7176/CPER/61-05 Publication date : July 31 st 2019

Highlights

The laser-induced breakdown spectrometry technique (LIBS), in which a short laser pulse is focused onto a sample surface to generate the plasma, the target can be solid, or liquid, or gas
2.3 Checking of the system The pure metal of Iron(Fe) and Lead (Pb) (99,99%) was used as a calibration samples to determine the emission spectrum lines emitted from these materials, and compare them with the emission lines of standard spectra maintained at National Institute of Standards and Technology (NIST)
The aim was known the ionization laser power density for writing inks to obtain a reasonable signal intensity for the elements originating from components of writing inks and without signal intensity for the elements originating from paper

Summary

Introduction

The laser-induced breakdown spectrometry technique (LIBS), in which a short laser pulse is focused onto a sample surface to generate the plasma, the target can be solid, or liquid, or gas. The possibilities of LIBS in the analysis of contemporary writing inks (Trejos 2010, El-Deftar 2014 , Hoehse 2012) In these procedures, LIBS was only a supplementary technique to laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) or Raman spectroscopy (RS). Hoehse et al concluded that revealing the presence of Cu, Ti, K, Ca, Na, Li, and Al in analyzed inks was insufficient to discriminate the sample set when separate LIBS data. These investigations showed the potential of utilizing the LIBS method in the field of document examinations for forensic purposes. Handwritten notes, such as signature is still required as proof of consent in many cases, such as altered wills and a prescriptions labels, business and personal cheques, traveler’s cheques and medical records continue to be widely used by people (Kula 2014)

Samples

Experimental setup

Measuring of laser beam diameter of the target

Results and discussion

Conclusions