Hyperfine Interaction, Zeeman and Stark Effects for Excited States in Potassium

Abstract

Using the optical double resonance and level crossing methods, properties of several excited S, P, and D states in 39K were studied. The S and D states were populated using stepwise excitation with the first P state as an intermediate level. An rf lamp and a CW dye laser were used in the first and second excitation steps, respectively. The studied P states were populated in the cascade decay of states, excited with the laser. The following results for the magnetic depole interaction constant a, the Landé gJ factor, and the tensor polarizability α2 were obtained for the studied states: 7 2 S 1/2: a = 10.78(5) MHz, g J = 2.0020(10); 8 2 S 1/2: a = 5.99(8) MHz, g J = 2.0028(12); 6 2 P 1/2: a = 4.05(7) MHz, g J = 0.6663(4); 6 2 P 3/2: a = 0.89(5) MHz, g J = 1.3337(8); 7 2 P 1/2: a = 2.18(5) MHz, g J = 0.6659(6); 7 2 P 3/2: a = 0.49(4) MHz, g J = 1.3336(8); 5 2 D 3/2: |a| = 0.44(10) MHz, g J = 0.7997(7), |α2| = 9.64(45) MHz/(kV)/cm)2; 5 2 D 5/2: |a| = 0.24(7) MHz, g J = 1.2004(10), |α2| = 13.4(7) MHz/(kV)/cm)2; 6 2 D 3/2: |a| = 0.2(2) MHz, g J = 0.7997(14), |α2| = 33.8(1.7) MHz/(kV)/cm)2; 6 2 D 5/2: |a| = 0.1(1) MHz, g J = 1.2013(20), |α2| = 47.6(2.4) MHz/(kV)/cm)2. Theoretical values for the magnetic dipole interaction constant have been obtained using a limited many-body perturbation expansion. The Polarization effect, which is due to single excitations from the restricted Hartree-Fock model, is included to all orders, while the true correlation effect is omitted. The results are compared with the experimental values, and the agreement is found to be quite good. For the S and P states the polarization effect is of the order of 10-20%, and it is responsible for roughly half of the deviation of the Hartree-Fock values from experiment. For the D states, on the other hand, the effects are much more drastic. The sign of the a factors has not been measured. The perturbative calculation yields positive values for all 2 D 3/2 states and negative values for all 2 D5/2 states. The theoretical magnitudes are in agreement with the observed ones.

Stark effect in 6s 5d and 5d 6p states in barium measured with laser-atomic-beam spectroscopy

“…The accuracy of the result thus depends not only on the accuracy of the calculated line strengths, but also on the contribution of the neglected bound states and the continuum. However, calculations made of the polarizabilities of the alkalis, taking into account only the contribution of bound states with principal quantum number n < 20, show fair agreement with experiment [2][3][4]. In the latter calculations the Bates-Darmgaard approximation [1] was applied.…”

“…However, a comparison of experimental polarizabilities with calculated values provides a sensitive test for atomic calculations, especially if the polarizabilities are known in a large number of states. For the alkalis it has been shown that the Coulomb approximation of Bates and Darmgaard [I] leads to fairly good agreement between calculated and experimental values for the tensor polarizabilities [2][3][4]. This is not surprising for these one-electron atoms, considering the predominance of the outer part of the electronic wavefunctions in the dipole matrix elements.…”

The elemental composition of the Sun

“…Good HFS measurements exist for all levels of the lines we derive abundances from. The most accurate data come from Bloom & Carr (1960), Dahmen & Penselin (1967), Svanberg (1971), Gupta et al (1973), Belin et al (1975), Sieradzan et al (1997) and Falke et al (2006). We prefer the results of Falke et al (2006) to those of for the 4p 2 P 1/2,3/2 levels, as data from the latter appear not to agree with other measurements (e.g.…”

Electric field induced hyperfine level-crossings in (nD)Cs at two-step laser excitation: Experiment and theory

“…This way of inducing level-crossings was preferred, perhaps because magnetic fields were easier to produce and control. Such techniques were used to measure the tensor polarizabilities α 2 of alkali atoms by Svanberg and co-authors (see [4,5,6,7] and references therein). In particular, this method was used in a two-step excitation with a radio-frequency discharge lamp and a narrow-width dye laser [5,6,7].…”