Landau-Zener crossings in magnetically trapped polar molecules

Paramagnetic polar molecules generically exhibit a number of avoided crossings between Zeeman manifolds of opposite parities in combined magnetic and electric fields. In the context of a magnetic trap, these avoided crossings become opportunities for molecules to Landau-Zener hop to untrapped states. We have observed this behavior in a model system, magnetically trapped OH and achieve near-quantitative agreement with a simple Landau-Zener theory.