Extensive new data on the odd-parity, single-colour, two-photon optogalvanic spectra of argon in the visible region is reported using an excimer-pumped dye laser in conjunction with an argon discharge cell. The experimental technique enables us to record a pure two-photon spectrum in a region which is dominated by one-photon transitions. A large number of two-photon transitions, originating from the two metastable states 3p 5 4s[3/2] 2 and 3p 5 4s [1/2] 0 to the excited states of configurations 3p 5 ns (J = 0, 2) and 3p 5 nd (J = 0-4) of argon, has been recorded and arranged into 10 Rydberg series. The interchannel interactions among the 3p 5 ( 2 P 1/2 )nd and the 3p 5 ( 2 P 3/2 )ns, nd J = 2 channels and the 3p 5 ( 2 P 1/2 )nd and the 3p 5 ( 2 P 3/2 nd J = 3 channels have been studied using the multichannel quantum defect theory (MQDT). In addition, higher members of the two-photon parity forbidden 3p 5 np series have also been detected.

We report extensive new data on the single-colour two-photon optogalvanic spectra of neon in the visible region. The experimental method enables us to record a pure two-photon spectrum in a region which is full of one-photon transitions. A large number of two-photon transitions originating from two metastable 3s(3/2)2, 3s'( 1/2 )0 states and one non-metastable 3s(3/2)I state of the 2p53s configuration of neon have been recorded and arranged into 19 Rydberg series. The interchannel interactions among the overlapping Rydberg series have been studied using the multichannel quantum defect theory.

We present a quantitative analysis of a brass alloy using laser induced breakdown spectroscopy, energy dispersive x-ray spectroscopy (EDX) and laser ablation time-of-flight mass spectrometry (LA-TOF-MS). The emission lines of copper (Cu I) and zinc (Zn I), and the constituent elements of the brass alloy were used to calculate the plasma parameters. The plasma temperature was calculated from the Boltzmann plot as (10 000 ± 1000) K and the electron number density was determined as (2.0 ± 0.5) × 10 17 cm −3 from the Stark-broadened Cu I line as well as using the Saha-Boltzmann equation. The elemental composition was deduced using these techniques: the Boltzmann plot method (70% Cu and 30% Zn), internal reference self-absorption correction (63.36% Cu and 36.64% Zn), EDX (61.75% Cu and 38.25% Zn), and LA-TOF (62% Cu and 38% Zn), whereas, the certified composition is (62% Cu and 38% Zn). It was observed that the internal reference self-absorption correction method yields analytical results comparable to that of EDX and LA-TOF-MS.

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