Date of Award
Doctor of Philosophy
A storage ion source based on the principle of confinement of charged particles by inhomogeneous oscillatory electric fields has been built for the production of low vibrational state ions. Using a gas mixture of H(,2) and rare gases (Ne and He) in the source at high pressure, higher vibrational states of H(,2)('+) and H(,3)('+) ions have been effectively quenched by ion-molecule reactions and collisional deactivation. State-selected ion beams of 10('-9)A or more have been obtained.;A new low energy crossed beam apparatus has been constructed to determine the internal energy of the ions by threshold measurement of collisional dissociation with a He jet. With a H(,2) + Ne (1:5 ratio) mixture in the source at 80 mtorr, H(,2)('+) ions are found to be in v = 0 and 1 states only. The H(,3)('+) ions have also been examined by collisional dissociation and are found to be in their ground vibrational states.;The H(,2)('+) ions from a colutron ion source have also been examined under similar conditions for comparison. The threshold measurements indicate that vibrational levels as high as v = 9 may be present.;In addition, vibrationally deexcited ions from a rf discharge source using rare gas mixtures with H(,2) at high pressure have been used to remeasure the dissociative recombination cross sections of H(,2)('+) through the energy range 0.01 - 1.0 eV in the MEIBE apparatus. Our calculations show that H(,2)('+) ions in vibrational levels up to v = 5 may be present contrary to the earlier belief of Auerbach et al. that only levels up to v = 2 were present. The DR cross sections are found to obey an E('-0.87) power law dependence and the derived rate coefficients satisfy an electron temperature dependence of T(,e)('-0.4) in the range 10('2)K to 10('4)K. Evidence of some structure in the cross section versus energy curves has been reaffirmed.
Sen, Amarjit, "Production Of Low Vibrational State Ions For Recombination Experiments" (1985). Digitized Theses. 1465.