Lw. Green et al., SELECTIVE RESONANT IONIZATION OF ZIRCONIUM ISOTOPES USING INTERMEDIATE-STATE ALIGNMENT, Physical review. A, 47(6), 1993, pp. 4946-4954
High selectivity (> 10) for separation of Zr-91 from other Zr isotopes
was observed during triple resonant ionization of Zr. vapors. Linearl
y polarized lasers were used to prepare aligned states, from which fur
ther excitation to a discovered J = 0 level could be suppressed for ev
en-mass isotopes, by a suitable choice of relative laser polarization.
Photoionization of the odd-mass isotope Zr-91 could be retained by us
e of transitions with relatively strong hyperfine interactions, becaus
e of associated population redistributions in the magnetic sublevels.
The dependence of the even-mass-isotope signals on relative laser pola
rization followed sinusoidal forms, which axe in excellent agreement w
ith predictions derived from the geometric components of the transitio
n dipole moment. The isotopic selectivity for Zr-91 can be increased b
y use of saturating fluences, because of the effects of saturation, po
pulation trapping in the even-mass isotopes, and strong hyperfine inte
ractions in the odd-mass isotopes. For the same reasons, biases in eve
n:odd isotope ratio measurements cannot always be eliminated by polari
zation scrambling or special angles.