Rydberg structure, observation

The electron in a metallic sphere (and the problem of the electron outside a metallic sphere) requires Dirichlet boundary conditions on the sphere. These problems were analyzed, for example in [84], In particular, it was noted, that the Rydberg structure of the electron spectrum near a metallic drop can be observed experimentally. 

Rydberg series were detected in molecular spectra in the early 1930 s, notably by W. C. Price who showed that they arose from the outer electrons. These can usually be fairly well classified in terms of the structure of the molecule, e.g. non-bonding electrons on particular atoms or electrons of double bond systems. Non-bonding electrons give more nearly atomic Rydberg series, with many numbers observable, and correspondingly accurate ionization potentials have been recorded. Most of the earlier measurements belong to this class. 

Bromoacctylene is linear in the ground state D0(Br —C2H) = 3.95 0.05 eV (773). Its absorption starts at 2800 A. Above 1730 A there are two continuous absorption bands with maxima at 2115 and 1780 A, while below 1730 A a number of Rydberg transitions are observed with complicated vibrational structure [Thomson and Warsop (970), Evans et al. (338)]. 

The absorption spectrum of water in the vacuum ultraviolet has been studied by Johns (533) and by Bell (92). Sharp rotational structure has been observed only below 1240 A (533). The 1240 A bands have been assigned to the 1 Bx —, 4, transition and is the lirst member of the Rydberg scries. The absorption coefficients of water in the vacuum ultraviolet have been measured by Watanabe ct al. (1016, 1018) and arc shown in Fig. VI I. The absorption coefficients of D2C) have been measured by Laufcr and McNesby in the region 1300 to 1800 A (601). 

All of the above observations are consistent with interpreting fine structure changing collisions in Rydberg atoms as elastic e -perturber scattering leading to... 

The depopulation cross sections of the Rb nd states of 25 < n < 40 are 1000 A2, which is the same as the cross section of the Rb ns state if the ns —> (n - 3)1,1 > 3 contribution is subtracted. For the Rb nd states the calculated contribution of the scattering of the nd state to nl S 3 and (n—1)1 s 3 states with no change in the rotational state of the CO is <100 A2, so 90% of the cross section is due to the inelastic transitions leading to rotational excitation. Presumably it is because the resonant transfer accounts for 90% of the observed cross section that the structure in the cross section is more visible in the nd cross sections than in the ns cross sections. For both the ns and nd states minimal collisional ionization is observed and calculated in this n range, principally because there are too few CO molecules with energetic enough A/ = -1 rotational transitions. For example, only CO 7 > 18 states can ionize an n = 42 Rydberg state by a A7 = -1 transition, and only 3% of the rotational population distribution is composed of 7 > 18 states. 

Fig. 23.13 Shifts of the centers of gravity compared to the ionic parent line positions for the observed structures for double Rydberg resonances 6snp —> 26dn p ( ) and 6snp — 27sn p ( ) vs n n = 39-47 and 50. The average quantum defect is 4.1 for the 6snp series. The full line is the theoretical curve (from ref. 34).

They observed two clear signatures of the Stark, or dipole, structure of the doubly excited states first in the quantum defects and second, in the overlap integrals. They observed several Rydberg series converging to excited Sr+ states. From the 5d c = 17 10 = 9 state they observed a series with a quantum defect of 0.70(mod 1) converging to the 6g state of Sr+. While the observation of a series converging to this limit alone is indicative of correlation, what is most interesting is the quantum defect. It is simply impossible for a Sr coulomb state of i = 9 to have a quantum defect of 0.70. On the other hand if the outer electron is not in a... 

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