Emission spectrum of chlorine excited in the presence of argon

The spectrum of chlorine excited in the presence of argon has been photographed with a 21-ft. grating spectrograph in the first order. Two band systems in the region 2600–2390 Å and 2365–2239 Å are observed which appear to be respectively analogous to the 2950–2670 Å and 2660–2590 Å systems of bromine reported earlier by Venkateswarlu and Verma. The wavelengths and the wavenumbers of all the bands in the system 2600–2390 Å are given. The vibrational scheme along with the corresponding Franck-Condon parabola is also given. The analysis suggests that the lower state of the system is the 3π(O _u ⁺_ state established by Elliott at 17658 cm.^?1 and that the upper state is at 67773 cm.^?1 The vibrational constants obtained arew ₀′ = 246·6 cm.^?1,w ₀′x ₀′ = 0·615 cm.^?1,w ₀″ = 255·2 cm.^?1,w ₀″x ₀″ = 5·5 cm.^?1,w ₀″y ₀″ = ?0·0155 cm.^?1 andw ₀″z ₀″ = 0·00115 cm.^?1