The emission spectrum of diatomic magnesium chloride molecule has been reinvestigated in the region 5030-4380 Å (B²Σ⁺ —A²Π transition) at a higher dispersion. The vibrational assignments of the bands are confirmed by observing the vibrational isotope shifts due to isotopes of magnesium and chlorine. Precise values of the vibrational constants are determined for theB²Σ⁺ state.

Magnesium chloride was excited in a high frequency discharge source and the 4730 Å band was photographed at an inverse dispersion of 0.48 Å mm⁻¹ in a two meter plane grating spectrograph. The rotational analysis of the band has been carried out and the molecular constants of the upperB²Σ⁺ state are reported for the first time. Observation of rotational isotopic shifts due to Cl³⁷ supports the rotational analysis. The electronic transition involved is identified to beB²Σ⁺ →A²Π_1/2(a) (inverted).

Nickel chloride was excited in a high frequency discharge source and the band at 3664 Å was photographed at an inverse dispersion of 0.59 Å/mm on a two metre plane grating spectrograph. The rotational analysis was carried out and the molecular constants of the upper state are reported. The rotational isotopic shifts due to³⁷Cl support the rotational analysis. The electronic transition involved is identified to beβ²Δ_5/2 →X₁²Δ_5/2.

The (1, 0), (0, 1) and (0, 2) bands ofD→X system of lead monoxide have been excited in RF discharge source and photographed in the seventh order of a 2-meter PGS. Intensity records of the rotational lines have been obtained. Rotational constants and the intensity measurements ofQ andP branch lines of the above three bands andJ numbering are used to calculate the effective rotational temperature of the source emitting the spectrum of²⁰⁸Pb¹⁶O molecule.