Laser induced breakdown spectroscopy using a second harmonic nano-second laser and enhancements the detection limits of trace elements in al-base alloy

الملخص EN

The enhancement of the emission intensity of spectra using a single laser for induced breakdown spectroscopy (LIBS) in atmospheric air is investigated based on methodology previously published in Applied Physics B: Lasers and Optics accepted 12 July 2013 DOI 10.1007/s00340-013-5589-9 [1].

The laser energy per pulse in the present study is 188 mJ and 20 mJ for the pulse duration of 5 ns FWHM which is nearly as in the use of the fundamental wavelength to present the wavelength dependence.

This corresponds to power densities (irradiance) of 7.73 × 1011 W/cm2 and 8.19 × 1010 W/cm2.

The emission spectrum is recorded using a SE 200 Catalina Echelle spectrometer and equipped with an ICCD camera.

This spectrometer allows time resolved spectral acquisition over the whole UV-NIR (200-1000 nm) spectral range.

This methodology depends on the accumulation of consecutively measured spectra on an ICCD at the optimum delay time which corresponds to the highest signal-to-noise ratio (SNR) for spectral lines free of self-absorption; here we produce the plasma by focusing the second harmonic pulsed Nd:YAG laser onto the Al target.

In this case, the method is more efficient than employing the laser at its fundamental wavelength (1064 nm).

Now the improvement factors increased by about 60-80% with respect to the results obtained in ref.[1] for Cu I, Mg I, Cr I, Fe I spectral lines and by 20% for Mn I spectral lines.

Even the present LOD for Cu I at 324.7 is higher with respect to the work done by Rai et al.[2] by about 92%.