The emission spectrum of PN molecule was excited in an electrodeless microwave discharge in sealed tubes containing phosphorus, nitrogen and neon. Isotope shifts of several bands of theA¹Π −X¹Σ⁺ system were studied using nitrogen isotope. Vibrational assignments of several bands were confirmed.

The ultraviolet band systemsA¹Π-X¹Σ⁺ of P¹⁴N and P¹⁵N were excited in an electrodeless tube containing traces of phosphorus specpure nitrogen and neon using a microwave discharge (2450 MHz). Bands of the isotopic species, P¹⁵N, were obtained using¹⁵N₂ enriched to 95.5%. Rotational analyses of eleven bands of P¹⁴N and sixteen bands of P¹⁵N were carried out. Three perturbing statese³Σ⁻,d³Δ andb³Π, arising from the lower valence configurations were identified from the observed perturbations in thev′=0–4 levels of theA¹Π state. Deperturbation studies led to the determination of molecular constants of the perturbing states. Vibrational assignments of the perturbing states were made from isotope shift studies.

The ultraviolet bands ofA¹Π-X¹Σ⁺ system of As¹⁴N and its isotopic species As¹⁵N were excited in a quartz tube containing specpure nitrogen and traces of AsCl₃ vapour, using a microwave discharge (2450 MHz). Bands of As¹⁵N were obtained using¹⁵N₂ enriched to 95.5%. Rotational structure of several bands of As¹⁴N and As¹⁵N photographed under high dispersion (0.14 Å/mm) was reanalysed. Detailed studies of the observed perturbations in the levels ofν′ = 0 to 4 led to the identification of two³Σ⁻ and aC¹Σ⁻ states. Molecular parametersT_e, ω_e, ω_ex_e, B_eandα_ewere determined for all the electronic states studied. Vibrational assignments of the perturbing levels were made using the isotope shift studies.

Optical emission spectroscopic studies were carried out to characterise the plasma leading to the estimation of two plasma parameters, electron density and temperature. These experiments were conducted on a 2 kJ plasma device which is equipped with squirrel cage electrode configuration enclosed in a glass vacuum chamber filled with hydrogen at a pressure of 5 mbar. Spectral emissions obtained from each flash were photographed in the region of 4000–6000 Å using one metre Czerny-Turner spectrograph cum monochromator. Detailed examination of the observed features showed that theH_β andH_λ lines of hydrogen showed significant broadening of the order of 35 Å FWHM which is due to Stark effect expected in high density plasmas. Further several atomic lines of Cu and Zn from the electrode material (brass) showed broadening which was due to quadratic Stark effect. A comparative study of the broadening of lines obtained in DC arc, hollow cathode and plasma focus was made. Electron density from Stark broadened hydrogen lines and quadratic Stark Coefficient C₄ for the CuI and ZnI lines were evaluated. The excitation temperature was determined from the line intensity ratio method using CuI lines.