Circular Rydberg states

Circular Rydberg States of H Atom in a Magnetic Field. 70... 

As this paper was nearing completion, the work of Germann et al. [21] appeared. In this work, dimensional perturbation theory has been employed to study circular Rydberg states of the H atom in a magnetic field. These authors... 

The approach of Germann et al. [21], in contrast to other procedures, is applicable to the entire range of magnetic field strengths. Energies and expectation values for circular Rydberg states are presented in this work as functions of the field strength. 

Mention should be made here of a new experiment using millimetre radiation (about 256 GHz) to determine the Rydberg constant from the energy spacings of neighbouring circular Rydberg states of atomic hydrogen [43] in a way essentially free of QED and the Lamb shift. 

As mentioned above, radiative studies of atoms in circular Rydberg states (such that = m n - 1) open the way to new promising applications. The valence electron distribution in these states has Che shape of a thin torus of radius n ao and width n ao (ao s Bohr radius) perpendicular to the quantization axis and centered around the atomic core. When compared to low and m Rydberg levels, circular Rydberg levels present the following advantages ... 

While ionization by linearly polarized fields has been well studied, there is only one report of ionization by a circularly polarized field, the ionization of Na by an 8.5 GHz field.36 In the experiment Na atoms in an atomic beam pass through a Fabry-Perot microwave cavity, where they are excited to a Rydberg state using two pulsed tunable dye lasers tuned to the 3s — 3p and 3p —> Rydberg transitions at 5890 A and —4140 A respectively. The atoms are excited to the Rydberg states in the presence of the circularly polarized microwave field which is turned off 1 fis after the laser pulses. Immediately afterwards a pulsed field is applied to the atoms to drive any ions produced by microwave ionization to a microchannel plate detector. To measure the ionization threshold field the ion current is measured as the microwave power is varied. 

Hi) In circular atoms, the Rydberg electron remains always very far from the nucleus. Hence, all the contact terms, which become significant corrections at the 10-AO level in the optical experiments and which depend upon the not-so-well known proton form factor, are in circular states completely negligible. Lamb-shift corrections are also very small for these states. From the point of view of Q. E. D. corrections, circular atoms are, by far, the best candidate for R metrology. 

The preparation of the Rydberg circular states Is performed by pulsed laser excitation followed by an adiabatic microwave transfer method (A.M.T. M.) already described in ref. [a]. This method requires that the atom interacts with an homogeneous electric field Fj., produced by the stack of equally spaced metallic plates shown on Fig. 1-a. This field removes the degeneracy of the various n-manifolds. 

To conclude this section we might assert that the main techniques for assessing the problem of Rydberg and valence excited states of organic molecules are, in practice, far-UV absorption spectra, photoelectron spectra, and advanced quantum chemical calculations. It should be added that the electronic spectra can also be obtained from electron-impact (energy loss) and circular dichroism spectra. The reader is referred to Robin s Volumes I to III [S, 23] he systematically considers the three kinds of spectra when they are available. 

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