Rotational Structure of the Red Bands of Sodium

Three bands of the red band system of sodium photographed at high dispersion have been measured. Two strong series of lines run through the bands and from the combination relations it is quite certain that these series are bona fide P and R branches. From the combination relations we find B₀^''=0.15435, D₀^''=-5.89×10^-7 and B₀^'=0.10846. The final state values are in close agreement with those of the final state of the blue green system and the constant for the upper state yields I₀^'=255.3×10^-40 gm cm² and r₀^'=3.52×10^-8 cm. Search is made for other branches but none are found. From a discussion of the possible electronic transitions it is concluded that the electronic transition is the ¹S-¹S type.