Fine-structure measurements in high-Ln=17and 20 Rydberg states of barium

Abstract

Fine-structure intervals in n = 17 and 20 barium Rydberg levels with 6 Յ L Յ 11 have been measured precisely with the resonant excitation Stark ionization spectroscopy microwave technique. The measured intervals were analyzed using the long-range polarization model, including allowance for the large nonadiabatic effects of the Ba + 5d level and the contributions of higher-order terms. The analysis determined improved values in atomic units of both dipole and quadrupole polarizabilities of Ba + , ␣ 1 = 123.88͑5͒ and ␣ 2 = 4420͑250͒.

Dipole transition strengths in Ba+from Rydberg fine-structure measurements in Ba and Ba+

“…Table V shows the measured K splittings in n = 17 and n = 20 of Ba, as reported by Snow et al [3]. As discussed in Ref.…”

“…[2], the reported intervals, in particular the highest (n,L) δE [3] NEW δE [3] TOT δE [4] NEW δE [4] TOT ( (7,9) −0.01 −0.17 −0.00 0.01 (20,9) −0.01 −0.12 −0.00 0.01 L splittings, are influenced by differential Stark shifts that were not considered in Ref. [3]. The splittings reported in column 3 of Table V have been corrected for these differential shifts, using f S = 0.13(4), as determined in Ref.…”

“…The only other experimental tests of these matrix elements, obtained from excited-state lifetime measurements, do not rule out errors on the order of a few percentage points. The implications of the K splitting measurements for these matrix elements can be explored by modifying the DD and QQ contributions to the splittings by variable factors: [3] + δE [4] ).…”

“…(2), which enhances the fractional effect of a change in the matrix element ratio. [3]. Column 3 shows the corrected interval after accounting for the differential Stark shift discussed in Ref.…”

“…A good example is the recent study of transition strengths in the Ba + ion [2]. A measurement of that ion's dipole polarizability, obtained from study of fine-structure patterns in high-L barium Rydberg levels [3], was combined with measurements of K splittings in the same Rydberg levels [3] to infer transition strengths between the 6 2 S 1/2 ground state of Ba + and the two 6 2 P excited levels. Both the dipole polarizability and the dipole contribution to the K splittings are almost entirely due to transitions to the 6 2 P levels.…”