Experimental and theoretical triple differential cross sections for electron impact ionization of aligned H$_{2}$

Most experiments measuring electron-impact ionization of molecules do not determine the orientation of the molecule at the time of ionization. One way to determine the orientation is to simultaneously ionize the molecule and excite the residual ion to a state that will dissociate. The orientation of the molecule can then be determined by detecting one of the dissociation fragments since the fragments will leave in the direction of orientation. Experimental and theoretical TDCS (triple differential cross sections) results will be presented for excitation-ionization of the $2s\sigma _g ,\;2p\sigma _u ,\;\mbox{and}\;\mbox{2p}\pi _u $ states of H$_{2}$ for three different orientations of the molecule.