Rydberg principal quantum number

It is essential to keep in mind that all atoms possess excited orbitals that may become involved in bond formation if one or more electrons occupies these orbitals. Whenever aos with principal quantum number one or more unit higher than that of the conventional aos becomes involved in bond formation, Rydberg mos are formed. 

The physical nature of the ZEKE states has been the subject of intense experimental and theoretical investigation in the past several years. In the well-studied case of NO,14,21 we know from the 3 cm-1 red shift of the ZEKE-PFI threshold band relative to the true adiabatic ionization potential (extrapolated from highly accurate measurements of Rydberg series) that the ZEKE states have principal quantum number n 200 and lifetime of 2 (is or longer. Recent work has found ZEKE states with lifetimes as long as 20 ps.22... 

When a Rydberg atom reduces its principal quantum number by one unit, when emitting a photon, the light is in the microwave region of the electromagnetic spectrum. With this radiation isolated Rydberg atoms can be observed in interstellar space, where interatomic collisions are rare. Atoms with n up to 350 have been observed by radio astronomical methods. 

The first task is to obtain an experimental value of the IS Lamb shift which is independent of the precise value of the Rydberg constant. This goal may be achieved by measuring two intervals with different principal quantum numbers. 

Here ERn is the energy of the Rydberg states, Er the ionization energy of the molecule, n the principal quantum number, S the quantum defect, and Ry the Rydberg constant. A measurement of the photoelectron spectrum immediately provides the Rydberg energies, because... 

Excited MOs whose main contributions come from AOs with principal quantum numbers equal to the atomic valence-shell quantum numbers are called sub-Rydberg (or valence) MOs. For example, the excited (antibonding) it MOs (symbolized by tt ) of conjugated molecules for which Clpir AOs make the main contribution are valence MOs. Another example is the o 15 MO of H2. Of course, there is not a sharp dividing line between Rydberg and valence MOs. One way to decide how much Rydberg character an MO has is to calculate for it. 

There are many motivations for the study of the unusual dynamics of high Rydberg states of molecules. The two that most capture my imagination are the exceptionally wide range of time scales involved (Fig. 1) and the unusual limiting situation of a very slow electron being perturbed by the faster motion of the nuclei in the core about which it revolves. What this means is that, as one varies the hydiogenic principal quantum number n, it is possible... 

K. Yamanouchi Recently, we investigated the interatomic potential VRyd(/ ) of the Rydberg states of a HgNe van der Waals dimer by optical-optical double-resonance spectroscopy. It was demonstrated that VRyd(/ ) sensitively varies as a function of the principal quantum number n [J. Chem. Phys., 98, 2675 (1993) ibid., 101, 7290 (1995) ibid., 102, 1129 (1995)], and in the lowest Rydberg states of Hg(7 3S )Ne and Hg(7 5o)Ne, the interatomic potentials exhibit a distinct barrier at around R 4 A. The existence of the barrier was interpreted in terms of a repulsive interaction caused by the Is Rydberg... 

Rydberg atoms, atoms in states of high principal quantum number, n, are atoms with exaggerated properties. While they have only been studied intensely since the nineteen seventies, they have played a role in atomic physics since the beginning of quantitative atomic spectroscopy. Their role in the early days of atomic spectroscopy is described by White.1... 

From the early spectroscopic work it is possible to construct an energy level diagram for Na, as shown in Fig. 1.1. From this figure it is apparent that the difference in the principal and sharp series limits is the wavenumber of the 3s-3p transition. It is also apparent that the Rydberg states, states of high principal quantum number n, lie close to the series limit. 

If this energy is equated to the energy of the Rydberg state, —Ry/n2, we find the classical field for ionization of a state of principal quantum number n... 

Using these assumptions they could then fit their data to determine excitation cross sections, o(n, Wo), for the excitation of a Rydberg state of principal quantum number n by an electron of energy W0. They found the values of o (W0) given in... 

Transitions in which the transition moment is at right angles to the internuclear axis are Q — N and the bands typically have low intensities. In molecular orbital terminology these are t - n transitions (9). Both V - N and Q - N transitions occur without a change in the principal quantum number and are valence shell transitions in contrast to Rydberg transitions, R - N where a change of the principal quantum number does occur. The symbol I describes a triplet state formed in a valence shell transition. 

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