Isotope shifts in the near infra-red bands of diatomic sulphur

Abstract

Studies of the near infra-red bands of diatomic sulphur (S₂) showed that they form two systems of bands involving (a) ³Π_g-³Δ_u and (b) ³Π_g-3σ⁺_u transitions with ³Π_g being the common initial level for both the systems. Bands of the isotopic molecules, ³²S ³⁴S and ³⁴S₂ (in addition to ³²S₂), have now been obtained. Vibrational and rotational analyses of these bands confirm the observations of earlier studies and show that the emitter of the near infrared bands is the diatomic sulphur molecule. Further, the isotope shifts provide a correct vibrational assignment of the bands in both the systems. The results of these investigations are presented in this communication.