Molecular structure measurements of swift complex ions traversing thin carbon foils

The final data and analysis of the Coulomb explosion of two molecular systems, C3+0- and NCO+0-, each measured in the positive, neutral and negative charge state are reported. In addition, a new measurement has been made with the CH2+ ion and preliminary results are reported. All of these complex molecules are produced as negative ions by either a sputtering process with solid materials (30 kV Cs+ ions on KCNO or C), or from a plasma by off-axis direct extraction of a duoplasmatron (operated with mixtures of H2, HN3 and CO2). Analysis of the three C3+0- species showed them all to have the same intranuclear separation found in normal neutral C3; 2.5(a)A, and similarly for the three NCO+0- species, except that the separation was rather small; 2.0(1)A. Preliminary analysis of the CH2+ data indicates that the best fit included angle, α/sub i/, between the two hydrogen atoms is 1220(3) with an average absolute deviation angle from equilibrium, Δα/sub i/, of 230(2) for a molecular model with linear uniform oscillation, and α/sub i/ = 1260(3), Δα/sub i/ = 190(2), for a model with simple harmonic oscillation. These preliminary values compare well with the measured value of 1150 for neutral CH2