  Absolute cross sections for the K-shell photoionization of Be-like boron ions
were measured with the ion-photon merged-beams technique at the Advanced Light
Source synchrotron radiation facility. High-resolution spectroscopy with
E/$\Delta$E up to 8800 ($\Delta$E $\sim$ 22 meV) covered the energy ranges
193.7 -- 194.7 eV and 209 -- 215 eV. Lifetimes of the strongest resonances are
determined with relative uncertainties down to approximately 4% for the
broadest resonance. The measured resonance strengths are consistent with 60 %
$\rm 1s^22s^2$ $^1S$ ground-state and 40 % $\rm 1s^22s2p$ $^3P^o$
metastable-state ions in the primary ion beam and confirmed by comparison with
independent absolute photo-recombination heavy-ion storage-ring measurements
with B$^{2+}$ ions using the principle of detailed balance. Experimental
determination of the line width for the $\rm 1s2s^22p$ $^1$P$^{\rm o}$
resonance gives a value of 47 $\pm$ 2 meV and compares favourably to a
theoretical estimate of 47 meV from the R-matrix with pseudo-states (RMPS)
method. The measured line widths of the $\rm 1s2s2p^2$ $^3$P, $^3$D resonances
are 10.0 $\pm$ 2 meV and 32 $\pm$ 3meV, respectively, compared to RMPS
theoretical estimates of 9 meV and 34 meV.
