Quadrupole Moment of Nb93 and Test of the Hyperfine Structure Formulas

Abstract

The hyperfine structure (hfs) of the spectrum of Nb I was studied by means of a liquid-air-cooled hollow cathode discharge tube and a Fabry-Pérot etalon. The quadrupole moment of Nb ⁹³ was deduced to be -0.29 barn and -0.20 barn (1 barn=10 ^-24 cm ² ) from the levels 4 d ³ 5 s ^{2 4} F _3/2 and 4 d ⁴ 5 s ⁶ D _3/2 respectively, in which no shielding correction is included. Assuming that the shielding correction in this case is zero, we get Q (Nb ⁹³ )=-0.2 ₅ ±0.1 ₅ barn. The interval factors of the levels 4 d ³ 5 s ^{2 4} F _{3/2, 5/2, 7/2, 9/2} and 4 d ⁴ 5 s ⁶ D _{3/2, 5/2, 7/2, 9/2} were measured and compared with hfs formulas, and a small but definite discrepancy was detected.