Band-Spectrum of Barium Oxide

Abstract

THE introduction of barium salts to flames or arcs leads, in presence of oxygen, to the production of a characteristic band-spectrum attributed to BaO. Mecke and Guillery¹ derived a band-head equation. Mahanti² gave a new vibrational analysis and also made a rotational analysis. From this the spectrum was shown to arise from a ¹Σ–¹Σ transition with B' _e = 0·30995, B" _e = 0·36440 cm.^-1 and r"_e = 1·787 X 10^-8 cm. On checking Mahanti's data, several discrepancies became apparent. Thus some of the plots of 2v₀ against J², [2v₀≃R(J-1) + P(J) 2(B – B') J² show anomalous changes of slope, some of the Combination differences agree rather poorly, and the usual graphical method for determination of B, namely, by plotting Δ"₂F(J)/ (J + ½) against (J + ½)², gives for B₂ another value than that quoted by Mahanti. These facts were disclosed by James³, who, from some relatively low-dispersion plates, was able to suggest an alternative rotational analysis with B" 0·31, B'≃0·26 cm.^'1.