Study of the ns²S and nd²D Rydberg series in aluminium

Abstract

The authors investigated the 3s2ns 2S Rydberg series and salient features of the 3s2nd 2D3/2, 5/2, series in free aluminium atoms. The high 2D and 2S levels were populated by stepwise excitation using 4s 2S1/2 as the intermediate state. They determined the position of the series members accurately from the normally forbidden 4s 2S-ns 2S and 4s 2S-nd 2D transitions (37<or=n<or=55) in a weak electric field. The 2S series is not perturbed; its quantum defect is 1.729(2). The 2D series is strongly perturbed by interaction with the 2D term of the 3s3p2 configuration and with other configurations. A new value for the ionisation limit is derived: 48278.372(1) cm-1. The fine-structure splitting of the high 2D levels has been estimated for the first time. The splitting is very large, due to a perturbation of the series. The authors' results are compared with other aluminium data as well as with data from the elements gallium and indium.

Microwave spectroscopy of Al I atoms in Rydberg states: D and G terms

“…Al(3s 2 nd)n 2 D states have been investigated by optical spectroscopy [1][2][3][4], but the results give values of the quantum defects of unknown accuracy whose values are unconfirmed. In these the doublet fine structure is at best only partially resolved [4].…”

Specification of the Ionization Potential of AlI

“…As a results we have obtained the sets of constants for calculation of quantum defect in S, P, D, and F states that fit best of all both microwave absorption spectra and optical spectra published by the authors of the works [1][2][3][4][5]. These sets of constants are presented in Table 1.…”

“…The last method is accepted as providing the highest accuracy of 1 cm -1 and higher. The authors of works [1][2][3][4][5] used this method to determine the ionization potential of Al atoms. We propose a method of specification of the ionization potential that based on the joining of the most accurate direct measurements of transition frequencies from the ground state to the excited states of the atom in optic wavelength range T nlj with highprecision calculations of atomic energy E(n,l,j) in Rydberg states.…”

“…The values T nlj can be taken from mentioned above works [1][2][3][4][5]. The E(n,l,j) component is the energy levels of Al corresponding to quantum number n, l, j may be parameterized by the Rydberg formula …”

“…If such "joining" of mentioned energies is fulfilled in the range with n > 4 the accuracy of V IP will be determined first of all by the accuracy of optic measurements. The values of ionization potential that were obtained earlier by the authors [1][2][3][4][5] are presented in Table 2. Our result is given in this table in the last row.…”