A critical analysis of the B 1Πu–X 1Σ+g band system of the Na2 molecule has been made. The body of data on which the present analysis is based is much more extensive than that used in any previous analysis. The data for the analysis were obtained by a laser-induced fluorescence technique in which many collisionally induced satellite fluorescence series were observed in addition to the directly excited series. We have found the coefficients in a Dunham expansion that replicates the frequencies of 12 591 lines that originate in 1297 different V′, J′ levels with an rms deviation between the observed and calculated frequencies of 0.011 cm−1. The frequencies of the lines that appear in the present analysis are poorly replicated by use of the Dunham coefficients found by earlier workers. The RKR potential curves, for both the B and X states and the Franck–Condon factors for transitions between the two states, have been found. In contrast to previous analyses the theoretical centrifugal distortion coefficients, calculated from the rotationless RKR potential, agree closely with those directly found in the present analysis. The dissociation energies have been found to be 5988 cm−1 for the X state and 3116 cm−1 for the B state. The maximum of the potential barrier of the B state lies about 474 cm−1 above the 2P3/2+2S1/2 levels to which the B state dissociates.

A theoretical analysis of mercury molecules

A new analysis of the A 1Σu+–X 1Σg+ band system of 7Li2 has been made. The analysis extends from v′=0 to v′=25, from v″=0 to v″=14, and up to J=78. The dissociation energy of the A state is found to be 8940 cm−1, considerably less than any earlier estimate of that energy. The RKR potential curves for the A and X states are given, together with the Franck–Condon factors for the A–X transition.

Erratum: Theoretical studies of the valence electronic states and the 1Π u ←X 1Σ g + absorption spectrum of the F2 molecule [J.The absorption and laser induced fluorescence spectra of the B Inu-x I~/ band system of the 7Li2 molecule has been photographed at high resolution (360000) and high dispersion (0.4 A/mm). Over 14000 spectral lines have been assigned to this band system for a wide range of rotational quantum numbers (J = 0 -80) and vibrational quantum numbers (v' = 0 -13 and v' = 0 -18). Using a Dunham type analysis, we have obtained the molecular constants for both states and have fitted 8358 nonoverlapping lines with an rms error of 0.012 em-I. The B In u lambda doubling constants, including the centrifugal distortion lambda doublet constant, have been determined. Quantum mechanical potential curves have been generated for this system using a novel variational procedure and Franck-Condon factors for different rotational quantum numbers have been determined over the range of vibrational levels observed. Excellent agreement has been achieved for the centrifugal distortion terms D" H" and Lv which were obtained from the least squares fit of the assigned lines and those calculated from the quantum mechanical rotationless potential. Levels above the 2 2p + 2 2S lI2 dissociation limit have been observed and a maximum for the barrier in the B In u potential of 450±50 cm-I above this atomic level was found. The dissociation energy, D: of the X l~g state was found to be 8600± 150 cm-I . A review of the literature on the Li2 molecule through 1977 is given. e e e 66 cent with the experimental values. Bader and Chandra,