Knowledge Bank

The vibrational levels of the mutually strongly perturbed 1 $1\Pi$ $-$ 2 $3\Sigma +$ $-$ $b$ $3\Pi$ states of $\mathrm{<mrow\; data-mjx-texclass="ORD">39</mrow>}$K$\mathrm{<mrow\; data-mjx-texclass="ORD">85</mrow>}$Rb, 18755 (2011).} were previously assigned by using a combination of molecular beam and ultracold molecule (UM) excitation spectra, the latter generated from levels of the $a$ $3\Sigma$$+$ state formed following photoassociation to a level of the 3(0$-$) state. In a follow-on study using the same techniques, we have now successfully assigned high vibrational levels of the $A$ and 3 $1\Sigma$$+$ states from the excitation spectra of UMs formed by PA to both 3(0$+$) and 3(0$-$) levels. The $1\Sigma$$+$ states are absent in the UM spectra for levels formed by the 3(0$-$) PA level. This absence has been explained by considering Hund's case (c) selection rules and the transition dipole moment calculations by Kotochigova $et$ $al$., 022501 (2003).} between the upper excited $A$ $1\Sigma$$+$(2(0$+$)) state and the three $\Omega$ components at the ground state dissociation limit.