Quadrupole Moment of Nb⁹³ and Test of the Hyperfine Structure Formulas

抄録

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 Nb⁹³ was deduced to be −0.29 barn and −0.20 barn (1barn=10⁻²⁴ cm²) from the levels 4d³5s^{2 4}F_3⁄2 and 4d⁴5s ⁶D_3⁄2 respectively, in which no shielding correction is included. Assuming that the shielding correction in this case is zero, we get Q(Nb⁹³)=−0.2₅±0.1₅ barn.
The interval factors of the levels 4d³5s^{2 4}F_{3⁄2,5⁄2,7⁄2,9⁄2} and 4d⁴5s ⁶D_{3⁄2,5⁄2,7⁄2,9⁄2} were measured and compared with hfs formulas, and a small but definite discrepancy was detected.