Pendular states and spectra of oriented linear molecules

Recent experiments have demonstrated the feasibility of orienting rotationally cooled polar molecules in an electric field. The anisotropy of the Stark effect allows molecules in low rotational states to be trapped in ``pendular states,'' confined to librate over a limited angular range about the field direction. We present calculations exhibiting the nature of these pendular states for a linear molecule and characteristic features of infrared and microwave spectra which become observable in strong fields.