Electronic transition-moment variation in the B1 − X1Σ+ system of PbO and determination of the effective vibrational temperature

Abstract

The B1 − X 1 Σ + (4200–5000 Å) system of PbO was excited in a vertical copper arc. Relative intensities of the bands were measured by using the photographic technique. The data were interpreted through appropriate use of Franck-Condon factors ( q v′ v″ ) and r-centroids ( r v′v″ ). It was found that the electronic transition moment varies as R e ( r) = const. (1−0.5408 r) for 2.02 ≤ r ≤ 2.148. A straight line plot of log ∑ υ″ logI υ′υ″ em V 4 against G′(v′) for v′ = 0, 1, 2, 3, 4, was made and the effective vibrational temperature has been calculated from the slope of this line to be 2240°K.