Rydberg molecules

In the second step the angular momentum of the Rydberg molecule may be randomized in collisions with ambient electrons (/-mixing and possibly m-mixing),... 

The second step in the reaction, dissociation of the Hej Rydberg molecule, is similar to dissociative recombination of He with a free electron. For this reason, Bates73 called this recombination mechanism Rydberg dissociative recombination. It enhances the overall loss rate of free electrons because the stabilization of He2 prevents the return of weakly bound electrons to the population of free electrons. The reaction plays the same role as the reaction of H with H2 that we discussed in Section IV.C. As has been discussed by Bates, the mechanism also provides an explanation for spectroscopic observations of atomic and molecular emissions in helium afterglows. There is direct evidence for the existence of a substantial population of weakly bound electrons in helium afterglows.74 Most likely, the weakly bound electrons are Rydberg electrons in He2 molecules. 

Apart from this classification, there are systems like Rydberg molecules where it is essential to take into account surface hopping between several coupled potential surfaces. 

In this context, it should be pointed out that an algebraic decay has also been numerically observed in classical Coulomb-type models of atomic autoionization processes by Blumel [141]. This might turn out to be relevant for Rydberg molecules, which also represent Coulomb-type systems. For the recent observation of algebraic decays in Rydberg atoms, see Ref. 142. 

Measurement of the survival probability of Rydberg molecules as a function of delay time for pulsed-field ionization. 

The MQDT picture [39, 40] of a Rydberg molecule in an electric field [41, 42] reveals much about the esential physics of the Rydberg stabilization problem. The space of the electron is divided primarily into three regions. The effects of the external field are only felt in the outermost region IB, where the total potential for the electron is a sum of Coulombic and external field terms (in a.u.)... 

L. Woste A speculative remark Could the Rydberg molecule even form a bubble in a gas cell (scattering environment) ... 

If these shift data really do represent the onset of an intermolecular electron transfer reaction in DABCO, ABCO, HMT clustered with amine, either, and aromatic solvents, one ought to be able to observe the reaction kinetics or dynamics. Consider the specific instance of DABCO. The singlet Rydberg state lifetime for DABCO (and all the other Rydberg molecules studied for this determination (Shang et al. 1993c, 1994a) is ca. 2 ps for the isolated molecule and ca. 1.2 ps for the nonpolar rare gas, hydrocarbon, and fluorocarbon solvents. This... 

It should be mentioned here that even though some transitions are theoretically predicted to have large transition probabilities, they may in practice be rather weak if the upper state is severely predissociated or is not significantly populated during the electron capture process that forms the Rydberg molecule from its parent cation. 

Rydberg Atoms High-Resolution Spectroscopy and Radiation Interaction—Rydberg Molecules, J. A. C. Gallas, G. Leuchs,... 

The prediction of molecular Rydberg spectra, as well as the analysis of the available laboratory data, has constituted a challenge on the theory. A number of ab initio calculations have been carried out on transition probabilities of Rydberg molecules, such as the frequently quoted Hartree-Fock (HF) study of H3 by King and Morokuma (15), the self-consistent-field frozen-core calculation with floating-spherical-Slater-type orbitals (FSSO) on the second-row Rydberg... 

We consider the QDO method to be a useful tool for estimating transition probablities between molecular Rydberg states. A drawback of our method is its empirical character in that it requires the quantum defects for the states involved in transitions as an input. However, the well established correspondence between the energy levels of a Rydberg molecule and those of its united atom limit (9), as well as the regular behavior of the quantum defects along a Rydberg series are very helpful in their estimations. 

The binding energy is so small that thermal energies would easily cause the Rydberg molecule to break apart. It is not likely to exist for much longer than a vibrational period. 

G. Herzberg, Rydberg molecules. Annu. Rev. Phys. Chem. 38,27 (1987)... 

Yamakita, Y., Procter, S.R., Goodgame, A.L., Softley, T.P., and Merkt, F., Deflection and deceleration of hydrogen Rydberg molecules in inhomogeneous electric fields, J. Chetn. Phys., 121,1419, 2004. 

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