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ture. Previous work at zero electric field (without long-range dipolar interactions) showed that the lifetime of the trapped $^{40}$K$^{87}$Rb molecules is limited by atom-exchange chemical reactions that proceed via p -wave scattering [21]. In our experiments, the typical transla- tional temperature of the molecular gas is 300 nK, while the energy height of the p -wave barrier for $^{40}$K$^{87}$Rb molecules corresponds to a temperature of approximately 24 µ K [22]. With the barrier height much larger than typical collision energies, scattering rates in the molecular cloud are determined by the tunneling rate through the centrifugal barrier and the molecular gas lifetime is relatively long (on the order of 1 s) [21]. 

In this paper, we investigate the effect of electric dipolar interactions on collisions and find a surprisingly large effect even for our relatively modest range of applied electric fields. 

