The Isotope Shift and Hyperfine Structure of Neutron Deficient Lead Isotopes.
Abstract
The isotope shift and hyperfine structure of 3 x 10('5) - y ('202)Pb and 52.1 - h('203)Pb (I = 5/2) were measured, in the 6p('2) ('3)P(,0) - 6p7s('3)p(,1)('o) 2833(ANGSTROM) atomic transition, as well as the nuclear spin of 1.43 x 10('7) - y('205)Pb. The shifts of the stable lead isotopes were also remeasured. High resolution optical absorption spectra of an atomic vapor of lead were obtained with a 9.1-m focal length Czerny-Turner spectrometer. In this instrument a 10-inch wide diffraction grating (resolving power (TURN)10('6)) blazed at 61(DEGREES) is used. Spectra were recorded both photographically and photoelectrically using a high positional resolution (0.5(mu)m), repetitive scanning system. Absorption cells containing < 10('12) atoms ((TURN)1 ng) of cyclotron produced radio-isotopes were constructed. For calibration, a narrow line-width absorption beam of natural lead was employed. The use of the atomic beam allowed us to obtain isotope shift results for the stable isotopes which differ significantly from older data in the literature. In contrast to prior photographic detection, the linearity of response afforded by the photoelectric method allowed us to obtain a direct measurement of the nuclear spin of ('205)Pb from the hyperfine structure intensity ratios. The measured isotope shifts are: Is(('202)Pb) = 6081(100)MHz, IS(('203)Pb) = 5730(90)MHz, and for the stable isotopes: IS(('204)Pb) = 4320(30)MHz, IS(('206)Pb) = 2235(20)MHz, IS(('207)Pb) = 1395(20)MHz, all toward the lower wavelength side of ('208)Pb. The odd-even staggering parameter ((gamma)(,N) = {IS(N + 1) - IS(N)}/ 1/2{IS(N + 2) - IS(N)}) for ('203)Pb is then (gamma)(,203) = 0.37. The hyperfine structure interaction constants for the ('3)P(,1)('o) level of ('203)Pb were found to be: A = 2013(20)MHz and (VBAR)B(VBAR) < 45MHz. Nuclear multipole moments were calculated from these constants: (mu)(('203)Pb) = +0.673(7)(mu)(,N) (uncorrected and (VBAR)Q(('203)Pb)(VBAR) < 0.22b (uncorrected). The magnetic dipole moment agrees with the value predicted by the nuclear shell model including configuration mixing and meson exchange contributions. The measured spin of ('205)Pb, I = 5/2, is in agreement with the value inferred from nuclear decay schemes.
- Publication:
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Ph.D. Thesis
- Pub Date:
- 1980
- Bibcode:
- 1980PhDT.......187M
- Keywords:
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- Physics: Atomic