Laser-induced resonant transition at 470.724 nm in the<i>v</i>=<i>n</i>-<i>l</i>-1=2 cascade of metastable antiprotonic helium atoms

Abstract

A laser-induced resonant transition in metastable antiprotonic helium atoms has been found at a wavelength of 470.724\ifmmode\pm\else\textpm\fi{}0.002 nm and assigned to the transition (n,l)=(37,34)\ensuremath{\rightarrow}(36,33). From the time evolution of the laser resonance intensity, the decay rate of the (37,34) state was determined to be 1.17\ifmmode\pm\else\textpm\fi{}0.09 \ensuremath{\mu}${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$, about 60% larger than the theoretical radiative decay rate. The sum of the initial populations in the v=n-l-1=2 decay chain was 23\ifmmode\pm\else\textpm\fi{}4% of the total number of metastable atoms formed.