Two-step predissociation of NaK

We use two-step excitation to measure predissociation rates and to map out high-lying molecular states of NaK. A single-mode ring dye laser is set at a particular 2 (A) 1Σ+ (v', J') left-arrow 1 (X)1Σ+(v double-prime, J double-prime) transition. Another single-mode laser (Ti-sapphire) is then used in the second step to excite the molecule, now in the A state, to a higher predissociating state. The predissociation is monitored by the atomic potassium emission on the 3D3/2 → 4P1/2 transition while bound state radiative processes are detected by total fluorescence and laser absorption methods. Absolute predissociation rates are determined by Doppler-free linewidths. By scanning the Ti-sapphire laser, different ro-vibrational states can be reached allowing us to map out and identify the states, involved in the predissociation process