We report the analysis of bound-free emission from the 4 3Σ + electronic state to the a(1) 3Σ + repulsive state of the NaK molecule. Taken together with the previous experiments of Burns et al. [J. Chem. Phys. 119 4743–4754 (2003)], recent measurements have provided data for a sufficiently large range of initial vibrational levels (up to v = 34 of the 4 3Σ + state) to probe the behavior of the transition dipole moment function M(R) in the range R ∼ 3.5 to 6.4 ˚A. This range includes a region where theoretical calculations have predicted sharp structure due to an avoided crossing. Using a modified inner repulsive wall for the a(1) 3Σ + potential and a refined IPA potential for the 4 3Σ + state, we have calculated bound free spectra and have adjusted M(R) to fit the experimental data. The work was performed with a version of R. J. Le Roy’s code BCONT that we modified. Preliminary results confirm the sharp structure predicted in M(R), and further work is in progress that will include both bound-free and bound-bound spectra in the analysis.