\begin{table}%t1
\caption{\label{lifetime}Calculated and experimental lifetimes  for Nb~II~levels of the 4d$^3$5p~configuration.}

\begin{tabular}{ccccccr}
\hline\hline 
                              &               & \multicolumn{3}{c}{Theory}                            &   \multicolumn{2}{c}{Experiment}        \\
Desig.\tablefootmark{a}               &   $E$\tablefootmark{a}  &   $\tau$(ns)  &   $\tau$(ns)  &   $\tau$(ns)       &   $\tau$(ns)   & $\tau$(ns)          \\
                              &   (cm$^{-1}$) &     {HFR(A)}  &      HFR(B)   &                    &                &                       \\
                              &               &    this work  &  this work    &      previous      &      this work &   previous        \\
\hline
\noalign{\smallskip}
4d$^3$($^4$F)5p   $^5$G$_2^\circ$ &   33 351.09    &   5.0         &   5.6         &                    &                &   5.9(4)\tablefootmark{e}      \\
4d$^3$($^4$F)5p   $^5$G$_3^\circ$ &   33 919.24    &   4.9         &   5.5         & 5.16\tablefootmark{b}, 6.53\tablefootmark{c} &                &   6.2(3)\tablefootmark{d}, 5.8(3)\tablefootmark{e}        \\
4d$^3$($^4$F)5p   $^5$G$_4^\circ$ &   34 632.03    &   4.7         &   5.3         &                    &                &   5.8(3)\tablefootmark{d}, 5.5(3)\tablefootmark{e}        \\
4d$^3$($^4$F)5p   $^3$D$_1^\circ$ &   34 886.35    &   5.1         &   5.9         &                    &   5.6(3)       &   5.5(3)\tablefootmark{d}, 5.7(3)\tablefootmark{e}        \\
4d$^3$($^4$F)5p   $^5$G$_5^\circ$ &   35 474.20    &   4.6         &   5.2         &                    &                &   5.3(3)\tablefootmark{d}, 5.3(3)\tablefootmark{e}        \\
4d$^3$($^4$F)5p   $^3$D$_2^\circ$ &   35 520.82    &   4.8         &   5.7         &                    &   5.5(3)       &   5.7(3)\tablefootmark{d}, 5.7(3)\tablefootmark{e}        \\
4d$^3$($^4$F)5p   $^5$G$_6^\circ$ &   36 455.46    &   4.4         &   5.0         &                    &                &   5.0(3)\tablefootmark{d}, 5.1(3)\tablefootmark{e}        \\
4d$^3$($^4$F)5p   $^3$D$_3^\circ$ &   36 553.24    &   4.2         &   5.0         & 4.67\tablefootmark{b}, 5.60\tablefootmark{c} &                &   5.0(3)\tablefootmark{d}, 5.0(3)\tablefootmark{e}        \\
4d$^3$($^4$F)5p   $^5$F$_1^\circ$ &   36 731.81    &   4.0         &   4.7         &                    &                &   4.7(3)\tablefootmark{e}      \\
4d$^3$($^4$F)5p   $^5$F$_2^\circ$ &   36 962.77    &   4.0         &   4.7         &                    &                &   4.7(3)\tablefootmark{e}      \\
4d$^3$($^4$F)5p   $^5$D$_0^\circ$ &   37 298.24    &   2.3         &   2.7         &                    &       2.6(2)   &   3.1(3)\tablefootmark{e}      \\
4d$^3$($^4$F)5p   $^5$F$_3^\circ$ &   37 376.90    &   3.9         &   4.6         &                    &                &   4.7(3)\tablefootmark{e}      \\
4d$^3$($^4$F)5p   $^5$D$_1^\circ$ &   37 480.08    &   2.4         &   2.7         &                    &                &   3.1(3)\tablefootmark{e}      \\
4d$^3$($^4$F)5p   $^5$F$_4^\circ$ &   37 528.38    &   3.8         &   4.4         &                    &                &   4.6(3)\tablefootmark{e}      \\
4d$^3$($^4$F)5p   $^5$D$_2^\circ$ &   37 797.32    &   2.6         &   2.8         &                    &        2.7(2)  &   3.2(3)\tablefootmark{e}      \\
4d$^3$($^4$F)5p   $^5$F$_5^\circ$ &   38 024.34    &   3.9         &   4.6         &                    &                &   4.6(3)\tablefootmark{e}      \\
4d$^3$($^4$F)5p   $^5$D$_3^\circ$ &   38 216.39    &   2.7         &   3.0         &                    &                &   3.4(3)\tablefootmark{e}      \\
4d$^3$($^4$F)5p   $^5$D$_4^\circ$ &   38 291.25    &   2.6         &   3.0         &                    &                &   3.3(3)\tablefootmark{e}      \\
4d$^3$($^4$F)5p   $^3$G$_3^\circ$ &   38 684.96    &   4.5         &   5.1         &                    &                &   5.0(3)\tablefootmark{e}      \\
4d$^3$($^4$F)5p   $^3$F$_2^\circ$ &   38 984.39    &   6.8         &   7.3         &                    &                &   7.3(3)\tablefootmark{e}      \\
4d$^3$($^4$F)5p   $^3$G$_4^\circ$ &   39 335.27    &   4.5         &   5.1         &                    &                &   5.1(3)\tablefootmark{e}      \\
4d$^3$($^4$F)5p   $^3$F$_3^\circ$ &   39 779.92    &   6.3         &   6.9         &                    &                &   6.8(3)\tablefootmark{e}      \\
4d$^3$($^4$F)5p   $^3$G$_5^\circ$ &   40 103.61    &   4.4         &   5.0         &                    &        5.1(3)  &   5.2(3)\tablefootmark{e}      \\
4d$^3$($^4$F)5p   $^3$F$_4^\circ$ &   40 561.02    &   5.8         &   6.3         &                    &                &   6.4(3)\tablefootmark{e}      \\
4d$^3$($^4$P)5p   $^3$P$_2^\circ$ &   41 710.14    &   7.9         &   8.4         &                    &        8.5(7)  &           \\
4d$^3$($^4$P)5p   $^3$P$_1^\circ$ &   42 132.65    &   6.5         &   7.2         &                    &        7.2(5)  &           \\
4d$^3$($^4$P)5p   $^5$D$_0^\circ$ &   42 596.55    &   6.3         &   7.2         &                    &        7.5(7)  &           \\
4d$^3$($^4$P)5p   $^5$D$_2^\circ$ &   43 290.34    &   6.9         &   7.3         &                    &        7.5(4)  &           \\
4d$^3$($^2$P)5p   $^1$D$_2^\circ$ &   43 618.39    &   6.4         &   6.7         &                    &        6.7(3)  &           \\
4d$^3$($^2$P)5p   $^3$D$_1^\circ$ &   43 649.19    &   8.4         &   8.1         &                    &        7.2(4)  &   12.8(3)\tablefootmark{e}     \\
4d$^3$($^4$P)5p   $^5$D$_3^\circ$ &   43 887.08    &   5.9         &   6.3         &                    &        5.7(5)  &           \\
4d$^3$($^4$P)5p   $^5$D$_1^\circ$ &   44 066.67    &   5.8         &   6.7         &                    &        6.4(5)  &   5.3(3)\tablefootmark{e}      \\
4d$^3$($^4$P)5p   $^3$P$_0^\circ$ &   44 285.94    &   6.6         &   7.5         &                    &        7.0(5)  &           \\
4d$^3$($^2$P)5p   $^3$D$_2^\circ$ &   44 924.60    &   5.9         &   6.6         &                    &        6.2(3)  &           \\
4d$^3$($^4$P)5p   $^5$D$_4^\circ$ &   44 970.71    &   5.1         &   5.8         &                    &        5.2(5)  &           \\
4d$^3$($^2$P)5p   $^3$D$_3^\circ$ &   45 802.47    &   4.9         &   4.6         &                    &        4.6(3)  &           \\
4d$^3$($^2$H)5p   $^3$H$_6^\circ$ &   48 770.84    &   4.5         &   3.7         &                    &                &   4.2(3)\tablefootmark{e}      \\[2pt]
\hline
\end{tabular}
\tablefoot {\tablefoottext{a}{From Ryabtsev et~al. (\cite{ryabtsev});}
\tablefoottext{b}{from Beck \& Datta (\cite{beck}): length form;}
\tablefoottext{c}{from Beck \& Datta (\cite{beck}): velocity form;}
\tablefoottext{d}{from Salih \& Lawler (\cite{salih});}
\tablefoottext{e}{from Hannaford et~al. (\cite{hannaford}). $A(B)$ is written for $A \pm B$.}}
\end{table}