We have studied the effects of the fine structure of energy levels on the dynamics of the atom and light field. A significant influence is exhibited in the collapse-revival behavior of atomic inversion, the light squeezing, the phase of the field, and the antibunching of a light beam. When the energy difference between the doublet is large (Δ≥20g, where g is the coupling constant), the dynamics of the atomic inversion becomes identical to that of the usual Jaynes-Cummings model, as expected. However, the fine-structure effects on the phase and the antibunching of the light field exist in a much larger range. In particular, for a strong field, the normally ordered variance of the photon-number operator exhibits complicated collapse and revival patterns and the light displays strong antibunching in each revival envelope. Numerical calculations also show that this model does not produce significant squeezing due to the influence of the fine structure. 

In our study of the interaction between few energy level atom and a coherent field, we considered the effect of the excited state's fine structure on the system dynamics. Significant influence exhibited on the collapse-revival behavior of atomic inversion and light squeezing. The numerical calculations show that for weak field, the effects of fine structure may cause disappearance of the collapse and revival phenomena. Our results also show the fine structure has opposite on the light squeezing, this observed on decrease of the amount of squeezing as the average photon number increased.

We report on the first clear observation of a collisionally induced diffuse band of lithium dimer around 452.0 nm in direct single photon excitation using 337.1 nm (N2) laser radiation from an excimer laser. The band, which is being tentatively assigned to the 2 1Σ+u → X 1Σ+g transition and could only be observed at buffer gas pressures of ⩾ 75 mbar, had been theoretically pre dicted. We also report on the other violet band of Li2 around 458.0 nm, already assigned to the 2 3Πg → a 3Σ+u transition. Parametr ic dependences for the two bands are presented. Together with these continuum emissions, a number of strong atomic lithium lines are also observed. A possible correlation between the atomic and continuum emissions is presented which may help in a better understanding of the kinetics of the system.