Valence-Rydberg perturbation

In this chapter we have implicitly assumed the Rydberg atom to be a one electron-atom. In the perturbed Rydberg series of, for example, alkaline earth atoms, Rydberg states can have mixed valence-Rydberg character. In such states the black body effects are reduced by a factor equal to the fractional Rydberg character.14... 

One of the most dramatic manifestations of an interference effect is the vanishing of a line or of an entire band that, on the basis of known Franck-Condon factors and inappropriately simple intensity borrowing ideas, should be quite intense (see Fig. 6.6). This effect can easily be mistaken as an accidental predissociation (Section 7.13). Yoshino, et al, (1979) have studied the valence Rydberg N2 b, E+ cVE+ perturbations. Abrupt decreases in emission intensity for c 4 — X1E+ (v = 1 and 4) and b — X (v = 4) bands had been attributed to weak predissociation rather than perturbation effects (Gaydon, 1944 Lofthus, 1957 Tilford and Wilkinson, 1964 Wilkinson and Houk, 1956). The b (v = 4) C4 (v = 1) and b (v = 13) C4 (v = 4) deperturbation models of Yoshino et al., (1979) provide a predissociation-ffee unified account of both level shift and intensity effects. Weak predissociation effects cannot be ruled out, but are not needed to account for the present experimental observations. 

Ba Rydberg energy levels (—) and continua (///) obtained by adding the second valence electron to these Ba+ levels. The horizontal arrows show the possible interactions between channels associated with different ion levels. Interactions with other bound states lead to series perturbations while interactions with continua lead to autoionization. 

Figure 3.7 2 A and 2n potential energy curves of NO. The C2II Rydberg state is homogeneously perturbed by the B2n valence state. Similarly, the F2A Rydberg state is perturbed by the B 2A valence state.

Figure 4.2 The 14N leO B2n (t>B = 24) C2n (vc = 6) L2n (vL = 5) D2E (vD = 6) perturbation. The deperturbed 2I1i/2 and 2n3/2 levels are plotted as solid lines (heavy lines for the valence B2n and L2II states, light lines for the Rydberg C2n state). The D2E+ e and / levels are plotted as dashed lines. The observed and calculated e-levels are indicated by solid and open circles, respectively. The observed (solid squares) and calculated (open squares) /-levels are shown only when the A-doubling is larger than 2.5 cm-1.

Electrostatic Perturbations Between Valence and Rydberg States.312... 

Figure 6.8 Calculated perturbed and deperturbed intensities for N2 1ntt <— XxS3 (v — 0) transitions. The valence b1nu and Rydberg c1IIu(3p7r) and o1] A2IIu, 3saj states...

Figure 7.25 Example of 2n 2n Rydberg vaJence electrostatic interaction in NO. The v = 0 and 1 levels of the 5pir Q2I1 Rydberg state are perturbed by bound levels (u = 29 and 35) of the B2n valence state, but the v > 2 levels of Q2n are predissociated by the continuum of the same B2II state. (Adapted from Gallusser and Dressier (1982).]...

---