Knowledge Bank

Optical-optical-optical triple resonance spectroscopy of $\mathrm{<mrow\; data-mjx-texclass="ORD">11</mrow>}$BH isolates high-Rydberg states that form series converging to rotational state specific ionization potentials in the vibrational levels of $\mathrm{<mrow\; data-mjx-texclass="ORD">11</mrow>}$BH$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$ from $v+=0$ through $4$. Limits defined by a comprehensive fit of these series to state-detailed thresholds yield rovibrational constants describing the X$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Sigma +$ state of $\mathrm{<mrow\; data-mjx-texclass="ORD">11</mrow>}$BH$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$. The data provide a first determination of the vibration-rotation interaction parameter ${\alpha}{e} = 0.4821 $cm$^{-1}$ and a more accurate estimate of ${\omega}{e} = 2526.58 $cm$^{-1}$ together with the higher-order anharmonic terms ${\omega}{e}x{e} = 61.98 $cm$^{-1}$ and ${\omega}{e}y{e} = -1.989 $cm$^{-1}$. The deperturbation and global fit of series to state-detailed limits also yields a precise value of the adiabatic ionization potential of $\mathrm{<mrow\; data-mjx-texclass="ORD">11</mrow>}$BH of $79120.3(1) $cm$^{-1}$, or $9.81033(1) $eV.$;$ High precision is afforded here by the use of graphical analysis techniques, narrow bandwidth laser systems, and an analysis of newly observed, high-principal quantum number Rydberg states that conform well with a Hund's case (d) electron-core coupling limit.