Spectroscopic study of a laser-produced lead plasma: experimental atomic transition probabilities for Pb III lines

Abstract

The optical emission from a laser produced plasma (LPP) generated by a I O 640 A laser irradiation, with a flux of 2 x 10 10 W cm-2 , on Pb targets was recorded and analysed between 2000 and 7000 A: spectral lines emitted by the first two ionization species of Pb were studied in a wide range of plasma parameters. First experimental values ofthe atomic transition probabilities for ten spectral lines of Pb III have been determined by measurement of ernission line intensities from an optically thin LPP of Pb in an atmosphere of Ar. The studied plasma has a temperature of about 25 300 K and an electron density of 10 17 cm-3 . Local thermodynamic equilibrium conditions and plasma homogeneity has been checked.

Experimental transition probabilities for several spectral lines arising from the 5d10 6s{8s, 7p, 5f, 5g} electronic configurations of Pb III

“…The experimental system is similar to that described in previous papers [2,[17][18][19][20][21][22][23][24][25], as more detailed description is presented in [17], only a brief description is given here. A diagram of the experimental device is shown in Fig.…”

“…Also, the excitation temperature was determined by means of a Boltzmann plot for three lines of Pb III (5d 10 6s7p 3 P 0^ 5d 10 6s7s 3 SÍ at 479.99, 5d 10 6s7p 3 P 1^5 d 10 6s7s 3 Si at 476.24 and 5d 10 6s7p 3 P 2^5 d 10 6s7s 3 Si at 385.53 nm), and was found to be 21,400 +1500 K for small A£=0.63 eV. The reason for selecting these lines is that the valúes of transition probabilities are experimentally known [2]. The linearity of the plots and the coincidence of the temperatures supported the existence of LTE.…”

“…The ionization temperature was calculated using the relative line intensity ratio method (in the electrón density 7 x 10 16 cm -3 ), Saha's equation [26][27][28], between Pb I (217.00 and 500.55 nm) and Pb II (220.35 and 504.26 nm), and also between Pb II (371.83 nm) and Pb III (385.41 nm) spectral lines; the necessary atomic data are taken from Refs. [2,18,19]. The valué obtained is 21,100 K with an estimated error of -10%.…”

“…The electrón number density of the plasma was determined, as in other papers [2,[18][19][20][21][22][23][24][25][31][32][33][34], by comparing the Stark broadening for some transitions with those of other authors. As is well known, the Stark line broadening from colusión of charged species is the primary mechanism influencing these emission spectra together with instrumental line broadening.…”

“…Some experimental transition probabilities, and theoretical valúes of oscillator strengths, transition probabilities and of some lifetimes, in Pb III have been the subject of three previous works carried out by this author. On the experimental side, the ten transition probabilities in the Pb III spectrum were measured using a plasma-induced láser, in an atmosphere of argón at 12 Torr, under local thermodynamic equilibrium (LTE) conditions [2]. On the theoretical side, transition probabilities of 54 lines for the 5d 10 6s 2 -5d 10 6snp, 5d 10 6sns-5d 10 6snp and 5d 10 6snd-5d 10 6snp spectral lines of Pb III presented in Colón and Alonso-Medina [3] were obtained in intermedíate coupling and using relativistic Hartree-Fork calculations.…”