We are extending the analysis of the bound-free emission from the 4 3Σ + electronic state to the a(1) 3Σ + repulsive state of the NaK molecule. In previous work, Burns et al. [J. Chem. Phys. 119 4743 4754 (2003)] measured spectra from initial vibrational levels up to v = 8, determined a refined potential for the 4 3Σ + state, and obtained relative values of the transition dipole moment function M(R) in the range R ∼ 3.8 ˚A to 4.6 ˚A. Recent measurements include data for many additional vibrational levels up to v = 34 of the 4 3Σ + state. The new data provide information about M(R) for larger values of R, including a region where theoretical calculations have predicted sharp structure due to an avoided crossing. Using a version of R. J. Le Roy’s code BCONT that we modified, we will obtain values M(R) for a larger range of R, and we will refine the inner repulsive wall of the potential for the a(1) 3Σ + state.