\begin{table}%t3
\caption{Experimental radiative lifetimes of \ion{Hf}{i}.\label{Table 1a}}
%\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 & DSL$^d$  \\
\hline
5d$^{2}$6s(a$^{4}$P)6p y$^{5}$D$^{o}$ & 31~342.51 & 3 & 3190.55 & 3730 & 63.5(4.5) & 62.3(3.1) \\
5d$^{2}$6s(b$^{2}$D)6p z$^{1}$D$^{o}$ & 31~610.80 & 2 & 3163.48 & 3850 & 19.3(1.7) & 18.7(0.9) \\
5d$^{2}$6s(a$^{4}$P)6p z$^{5}$P$^{o}$ & 33~121.48 & 2 & 3250.47 & 3020 & 15.3(1.5) &  \\
                                      & 33~538.15 & 2 & 3207.03 & 2980 & 11.2(1.1) &  \\
                                      & 34~877.04 & 3 & 2867.22 & 2870 &  5.7(0.7) &  \\
                                      & 46~170.12 & 2 & 2165.90 & 3180 & 12.2(1.2) &  \\
                                      & 46~775.98 & 3 & 2137.85 & 2760 & 13.0(1.2) &  \\
                                      & 47~590.09 & 3 & 2101.28 & 3240 &  6.7(0.5) &  \\
\hline
\end{tabular}}
\par
\smallskip
$^a$  {Notation from \cite{Moore52}}.\\
$^b$  {Laser wavelength used to populate the upper state}.\\
$^c$  {Wavelength used to detect the fluorescence signal}.\\
$^d$  {DSL = \cite{Duquette82}}.
\end{table}