Determination of polarizabilities and lifetimes for the Mg, Zn, Cd and Hg isoelectronic sequences

The dipole polarizability and adiabatic correlations of atomic ions are related to the energy levels and oscillator strengths of the levels through bracketing inequalities. For systems with a ground state ns(2) S-1(0), the total oscillator strength is dominated by the unbranched intrashell ns(2) S-1(0)-nsnp P-1(1)o transition, and the remaining oscillator strength can be narrowly bracketed using the f-sum rule. Thus measurements of the lifetime of the lowest resonance transition can be used to specify the polarizabilities and, alternatively, measurements of the polarizabilities can be used to deduce lifetimes. Moreover, isoelectronic regularities in line strengths can be used to obtain a comprehensive database from a small number of precision lifetime determinations. These methods are applied homologously to produce values for polarizabilities and lifetimes for the Mg, Zn, Cd and Hg isoelectronic sequences. To confirm the reliability of these methods, fast ion beam lifetime measurements in P IV were performed using the arbitrarily normalized decay curve (ANDC) method, and a test of the f-sum was made for Ba II, for which precision measurements of both the polarizability and lifetimes exist.