The spectrum of boron monosulphide has been excited in microwave discharge and photographed at moderate dispersion. TheC²Π_r−X²Σ⁺,B²Σ⁺−A²Π_i andA²Π_i−X²Σ⁺ band systems extending from 2100–9000 Å have been obtained for B³²S and B³⁴S species. Isotope shifts for all these band systems have been measured. Comparison of the observed isotope shifts with the theoretically calculated isotope shifts confirms the emitter as well as the vibrational assignments of all these band systems.

In the electronic spectrum of silicon monotelluride which has been produced in microwave discharges through sealed tubes, a large number of new bands belonging to theA¹Π-X¹Σ⁺ system (3100–3900 Å) and theE¹Σ⁺-X¹Σ⁺ system (2800–3100 Å) of Si¹³⁰Te has been observed. The vibrational structure analyses of these band systems have resulted in the determination of improved vibrational constants in all the three electronic states involved in these transitions. An error in the previous determination of the vibrational constants of theE¹Σ⁺ state has been corrected. An upper limit for the dissociation energy of the silicon monotelluride has been determined to be 40,000 cm⁻¹.