\begin{table}%t4
\caption{Experimental radiative lifetimes of \ion{Hf}{ii}.\label{Table 1b}}
%\centerline
{\begin{tabular}{lccccrr}
\hline\hline
Configuration$^a$ & Energy & \emph{J} & $\lambda_{\rm exc}^b$ & $\lambda_{\rm obs}^c$ & \multicolumn{2}{c}{Exp. lifetime (ns)}\\
 & \cm &  & (\AA) & (\AA) & This work & APH$^d$ \\
 \hline
 5d6s(a$^{3}$D)6p z$^{4}$F$^{o}$     & 29~405.129 & 2.5 & 3794.46 & 3400 & 29.7(2.4) & 21(3) \\
                                     & 33~776.300 & 3.5 & 3254.64 & 3650 & 34.8(2.5) & 23(3) \\
 5d6s(a$^{3}$D)6p z$^{4}$D$^{o}$     & 31~784.202 & 1.5 & 3146.22 & 3720 & 21.8(1.8) & 20(3) \\
                                     & 34~355.172 & 2.5 & 2910.77 & 3570 & 16.2(1.4) & 14.5(2.0) \\
 5d6s(a$^{1}$D)6p z$^{2}$D$^{o}$     & 33~180.970 & 2.5 & 3318.99 & 3010 & 18.1(1.5) & 16(2) \\
                                     & 34~123.965 & 1.5 & 3218.22 & 3280 & 24.5(2.5) &  \\
5d$^{2}$ (a$^{3}$F)6p z$^{4}$G$^{o}$ & 34~942.411 & 2.5 & 3195.12 & 3500 &  8.4(0.5) &  \\
                                     & 38~498.566 & 3.5 & 2821.06 & 3110 &  5.1(0.3) &  \\
5d$^{2}$ (a$^{3}$F)6p y$^{4}$F$^{o}$ & 42~518.148 & 1.5 & 2351.94 & 2530 &  2.3(0.2) &  \\
                                     & 43~680.787 & 2.5 & 2289.34 & 5650 &  3.3(0.2) &  \\
5d6s(a$^{1}$D)6p y$^{2}$P$^{o}$      & 42~770.596 & 1.5 & 2338.06 & 2520 &  2.6(0.2) &  \\
                                     & 43~044.258 & 0.5 & 2323.19 & 2540 &  1.8(0.2) &  \\
5d$^{2}$ (a$^{3}$F)6p y$^{4}$D$^{o}$ & 45~643.263 & 0.5 & 2190.90 & 2970 &  2.2(0.2) &  \\
                                     & 46~674.354 & 1.5 & 2142.50 & 2390 &  2.1(0.2) &  \\
                                     & 47~904.443 & 2.5 & 2087.49 & 3810 &  2.0(0.2) &  \\
5d$^{2}$ (a$^{3}$P)6p z$^{2}$S$^{o}$ & 46~495.401 & 0.5 & 2150.75 & 3200 &  2.7(0.2) &  \\
5d$^{2}$ (a$^{3}$F)6p z$^{2}$G$^{o}$ & 49~840.585 & 4.5 & 2299.06 & 3080 &  3.1(0.2) &  \\
5d$^{2}$ (a$^{3}$F)6p x$^{2}$F$^{o}$ & 52~340.079 & 3.5 & 2108.04 & 2680 &  1.9(0.2) &  \\
\hline
\end{tabular}}
\par
\smallskip
$^a$   {Notation from \cite{Wyart90}}.\\
$^b$  {Laser wavelength used to populate the upper state}.\\
$^c$  {Wavelength used to detect the fluorescence signal}.\\
$^d$  {APH = \cite{Andersen76}}.
\end{table}