Focusing and Orienting Asymmetric-Top Molecules in Molecular Beams

Asymmetric-top molecules can be deflected in an inhomogeneous electric field, and the deflected molecules can be oriented by allowing them to pass adiabatically into a uniform field. It is possible to account quantitatively for the transmission in a hexapole field if only first order and intermediate (or fast) Stark effects are considered. Rigid rotors with the dipole moment parallel to the a axis and internal rotors with low barriers to rotation have many levels which so interact and these types of molecules are easily deflected. Rigid rotors with the dipole parallel to the b axis have far fewer levels which interact; for these molecules the deflection is weak and may be undetectable. For rigid rotors and free internal rotors it is possible to obtain dipole moments by matching theoretical curves with experimental points.