Excited States Of Alkali Atoms Research Articles

Low-pressure cesium and potassium diode pumped alkali lasers: pros and cons

This paper presents the results of our experiments on a comparative study of cesium and potassium diode pumped alkali lasers (DPALs) aimed to determine which of these two lasers has more potential to scale to high powers. For both lasers, we have chosen a “low-pressure DPAL approach,” which uses buffer gas pressure of about 1 atm for spin-orbit mixing of the excited states of alkali atoms to provide population inversion in the gain medium. The goal of this study was to determine power-limiting effects, which affect the performance of these DPALs, and find out how these limiting effects can be mitigated. We studied the performance of both lasers in CW and pulsed modes using both static and flowing gain medium and pump with different pulse duration. We observed output power degradation in time from the initial value to the level corresponding to the CW mode of operation. As a result of this study, some essential positive and negative features of both DPALs were revealed, which should be taken into account for power-scaling experiments.

Source for excited states of alkali atoms and clusters using diffusion through a thin graphite foil

A molecular beam source used for the production of excited and ionized clusters of Cs and other materials is described. This source is closed, with the emitting graphite foil as an integral part of the source enclosure. The foil is kept at 1100–1500 K by radiation heating. From the foil, excited clusters (Cs)*n with broad distributions of n, and excited Rydberg atoms Cs* are emitted. These highly excited states can be field ionized at field strengths of less than 400 V/cm. At a Cs reservoir temperature of 400 K, total field ionized flux densities up to 1015 ions cm−2 s−1 (3×10−4 A cm−2) are found.

Alkali promotor function in heterogeneous catalysis: Possibility of interaction in the form of Rydberg states

The promotor function of alkalis in heterogeneous catalysis is proposed to involve excited states of alkali atoms at the surface. These states are formed during the emission of alkali ions from the bulk. During the transit out from the bulk, the ions attach electrons in high lying levels and form highly excited states, so-called Rydberg states. Such a highly state A ∗ may react easily with most molecules R on the surface, to form complexes RA ∗ or RA and finally possibly RA +. This means that the molecule R is attacked chemically in a way which resembles standard organic chemical synthesis methods. The excited states are proposed to be formed thermally, but at non-equilibrium concentrations. The theoretical and experimental evidence for this is summarized and discussed.

Wavefunctions and oscillator strengths of high Rydberg alkali atoms by a simple atomic potential model

The analytical wavefunctions and oscillator strengths between highly excited states of alkali atoms over a wide range of principal quantum number n(10<or=n<or=40, and for Na, n<or=60) are calculated straightforwardly by using a simple, one-parameter, exactly soluble model for atoms. The valence electron of the atom is assumed to be in a potential of the following form: V(r)=-e/r1+ delta + alpha '/r+ gamma '+ beta '/(r+ gamma ')2 where alpha ', beta ', gamma ' are the parameters to be determined and delta is the ionicity. Analytical solutions can be obtained by solving the Schrodinger equation containing V(r). The parameters in the potential and the wavefunction, which are dependent on the atomic states, can be expressed in terms of a single parameter, the quantum defect. The wavefunctions of the alkali atoms were obtained, and their general behaviour and the number of nodes agree with Hartree-Fock-Slater theory. This model is well suited for studying the behaviour of atoms that are mainly dependent of the outer region of high Rydberg states.

Similarities between solvated ground states and gaseous excited states of alkali atoms

Similarities between solvated ground states and gaseous excited states of alkali atoms

Calculation of radial matrix elements and radiative lifetimes for highly excited states of alkali atoms using the Coulomb approximation

Calculation of radial matrix elements and radiative lifetimes for highly excited states of alkali atoms using the Coulomb approximation

Many-body calculations of the hyperfine interaction of some excited states of alkali atoms, using approximate Brueckner or natural orbitals

The theory of maximum-overlap or Brueckner orbitals and of natural Orbitals is reviewed for closed-shell systems. A technique is described to calculate approximate Brueckner or natural orbitals for systems with a single valence electron, and this is applied together with the linked-diagram expansion of effective operators to evaluate the hyperfine interaction of some excited states of alkali atoms. It is found that it is in this way possible to reproduce reasonably well also the highly perturbed interactions of the excitedd states, which is not possible in a low-order expansion based on HF orbitals. Numerical results are given for the 5d state in K and the 4d state in Rb, where good experimental information is available.