Electronic Alignment of HYDROGEN(2P) from Oriented Excited State Dihydrogen Cation Produced in 4.0 KEV Dihydrogen Cation Collisions with Helium

The electronic alignment of H(2p) from oriented (H{2}{+})^ {*} produced in 4.0 keV H {2}{+} collisions with helium is investigated for a variety of center-of-mass energies of the fragment particles. The experiment is performed by measuring the polarization of L_alpha in coincidence with the charged particle scattered at a specific laboratory scattering angle. The laboratory scattering angle and the laboratory energy of the charged particle not only specifies the instantaneous orientation of the parent molecule relative to the incident beam velocity, but also the center-of-mass energy of the fragment particles. Photon and proton detection systems were specially designed and implemented to increase data collection efficiency. This was important because of the time-consuming nature of the photon-particle coincidence method. In special cases, symmetry arguments for the collision system are employed in order to qualitatively assess and predict the characteristics of the nascent charge cloud. These arguments also help one to qualitatively predict the possible symmetries of the excited states of the parent molecule. The results are discussed in order to determine the efficacy of existing models for the (HeH_2) ^+ complex.