Laser Plasma Characterization and Atomic Structure Calculations of Ti II

In this work, we report estimates of the temperature and electron density of titanium plasmas using time-resolved laser-induced breakdown spectroscopy (LIBS) methods and results of Hartree–Fock relativistic (HFR) calculations of Ti II transition probabilities. Plasmas were generated on certified grade-1 titanium samples, with 532-nm laser radiation pulses from a Nd:YAG laser with energies of 18, 28, 38, and 48 mJ. Spectra were recorded with delay times between 0.5 and
$6.5~\mu \text{s}$
with 0.5-
$\mu \text{s}$
intervals. The calculation of Ti II transition probabilities included reported configurations of the Rydberg series as well as six new unreported configurations of each parity. For the estimation of the electronic temperature using the Boltzmann plot, 13 Ti II lines and eight Ti I lines measured in the LIBS spectra of the plasmas were used, obtaining values between 7700K and 11700 K with an uncertainty around 15%. On the other hand, the estimated plasma electron density range was (9–18)
$\times 10^{16}$
cm-3, with an uncertainty of about 20% using a Lorentzian fit of the Stark broadening of measured Ti II lines. A comparison of the obtained electron density with that calculated from the Saha–Boltzmann equation is also presented.