One example of molecular hyperfine structure in theΠ1state: Study of theBΠ1→XΣ1transition of the LuF molecule

Abstract

The accurate measurements obtained with Fabry-Perot spectrometry allowed a detailed determination of the main hyperfine interactions in the (0-0) $B^{1}\ensuremath{\Pi}\ensuremath{\rightarrow}X^{1}\ensuremath{\Sigma}$ transition of the LuF molecule. The corresponding parameters are ${Q}_{0,0}=\ensuremath{-}35\ifmmode\pm\else\textpm\fi{}5$ mK, ${Q}_{1,1}=\ensuremath{-}30\ifmmode\pm\else\textpm\fi{}4$ mK, ${Q}_{1,\ensuremath{-}1}=\ensuremath{-}34\ifmmode\pm\else\textpm\fi{}3$ mK, ${G}_{\mathrm{Lu}}=53\ifmmode\pm\else\textpm\fi{}3$ mK, and ${G}_{\mathrm{F}}\ensuremath{\le}7$ mK. Then it is shown that these parameters give important information on the LuF bond and its origin: high ionicity (> 95%), high $c$ tendency for the excited $^{1}\ensuremath{\Pi}$ state, probable atomic origin of molecular configurations: $6s6p(\mathrm{Lu}\mathrm{II})\ensuremath{\rightarrow}(6s\ensuremath{\sigma})(6p\ensuremath{\pi})$ and $6{s}^{2}(\mathrm{Lu}\mathrm{II})\ensuremath{\rightarrow}{(6s\ensuremath{\sigma})}^{2}$.