W. S. Koski

Ion–Molecule Reactions of C+ with N2 and O2

Using a tandem mass spectrometer, the reactions C++X2→X2++C →X+X++C →CX++C, where X is either nitrogen or oxygen, were studied in the ion energy range 5–200 eV. By studying the attenuation of the C+ ion beam as a function of N2 pressure at various electron energies, and by measuring the ion–molecule reaction cross sections at different electron energies, it was possible to estimate the contribution of the 2P and 4P states of C+ to the reactions.

Electron Spin Resonance of Some Vanadyl Porphyrins

The electron spin resonance spectra of the vanadyl complexes of etioporphyrin II, vanadyl mesoporphyrin IX dimethyl ester, and deuteroporphyrin IX dimethyl ester have been studied and found to be identical to within experimental error. Unlike the corresponding copper complexes, the vanadyl complexes give no observable nitrogen hyperfine effects. An explanation is proposed for the lack of this hyperfine structure, and an approximate method is suggested for evaluating the bonding parameters.

Theoretical Justification of the Apparently Anomalous Low‐Energy Behavior of Some Ion–Molecule Reactions

It is generally observed that cross sections for exothermic ion–molecule reactions decrease with increasing ion kinetic energies indicating a negligible activation energy. An important exception to this behavior is exhibited by the exothermic reaction O++N2→NO++N, the cross section of which goes through a maximum as a function of ion energies. A study of the pertinent potential‐energy curves, taking into account the proper symmetry‐ and spin‐allowed combinations of the reactants and products, shows the origin of the apparently anomalous behavior of this reaction.

Kinematics of the C+(D2, D)CD+ Reaction

The energy and angular distributions of CD+ formed by the reaction C+(D2, D)CD+ were measured for barycentric energies between 3.47 and 9.14 eV. From the threshold to an energy of 4.4 eV the reaction was found to go through a persistent complex, and at higher energies the reaction proceeded by direct mechanisms. CD+ was detected at energies considerably higher than the critical energy obtainable from the spectator stripping model. Measured values of Q, the difference between the relative kinetic energy of the products and reactants, and available theoretical calculations were used to infer the possible electronic states of the products.

Reaction of D3O+ with D2: Proton affinity of water

The cross section for the endothermic ion‐molecule reaction: D3O+(D2,D2O)D3O+ has been studied over the energy range 2–70 eV using a tandem mass spectrometer. The projectile beam was found to contain a significant fraction of the D3O+ in an excited electronic state which was relatively insensitive to collisional deactivation using high pressures but was readily deactivated using the paramagnetic gas NO in the primary ion source. Threshold measurements, using the ground state D3O+ beam, permitted a determination of the proton affinity of water and the conclusion that the reaction proceeded through a persistent intermediate complex at energies close to the threshold.

Reactive scattering of B+ (3Pu) by molecular deuterium

The angular and energy distribution of the ionic products from the reaction of B+ in its first excited state, 3Pu, with molecular deuterium was studied over a projectile energy range of 1 to 40 eV in the laboratory system. The product states as determined from the limiting values of the translational exoergicity were BD+  (2Σ+) and BD+  (2Π). The experimental velocity contour maps indicated that BD+(2Σ+) was arising through complex formation whereas BD+  (2Π) was proceeding by a direct mechanism.

Kinetics of Two Exchange Reactions Involving Diborane

The kinetics of the exchange between deuterium and diborane were studied over a temperature range of 25°—75°C, and it was found that the reaction was 32 order with respect to diborane and zero order with respect to deuterium at high pressures. At low pressures the zero‐order dependence of the deuterium changed to first‐order. The activation energy of the zero‐order reaction was 20.4±2 kcal/mole. A mechanism is proposed in which the borine radical reacts with deuterium on the wall and is followed by a rate determining bimolecular collision between the partially deuterated borine radical and a diborane molecule.The closely related exchange reaction between normal and completely deuterated diborane was also investigated. The total order of this reaction was 32, and it had an activation energy of 21.8±3 kcal/mole. A mechanism is proposed which involves the collision between a borine radical and a diborane molecule as the rate determining step.

Dynamics of the reaction of F+ with D2

The energy and angular distribution of the ionic products from the reaction F+(D2,D)FD+ were measured as a function of primary ion energy ranging from 0.7 to 12.5 eV in the laboratory system. At the low energies the distribution showed a high degree of symmetry although some forward peaking was detectable. At the higher energies the distribution was asymmetric relative to ±90° indicating that the reaction was proceeding by an impulsive direct mechanism. A study of the exoergicity as a function of projectile energy shows that the bulk of the exothermicity of the reaction is converted into vibrational energy in the product ion. Failure to observe the reaction F+(D2,FD)D+ was attributed to a violation of the spin and symmetry conservation rules.

Internal energy of CH+ produced by the C+(H2,H)CH+ reaction

The energy spectrum of CH+ from the reaction C+(H2,H)CH+ was measured with a tandem mass spectrometer with improved energy resolution as a function of projectile kinetic energy. These spectra indicate the presence of the three lowest electronic states of CH+ and product vibrational excitation was observed in favorable cases. The internal energy distribution in the CH+ product was in satisfactory agreement with published results of phase space theory calculations for this reaction.

Reactions of H2O+ and D2O+ with Molecular Hydrogen. I. Proton Affinity of Hydrogen

The cross section of the ion molecule reaction H2O++H2→ H3++OH and its deuterium counterpart was studied over an energy range 2–100 eV using a tandem mass spectrometer. The measurements permitted a determination of the proton affinity of H2 of 4.37± 0.05 eV and 4.50± 0.05 eV for D2. The energy threshold values indicate that the reaction is proceeding by complex formation at low energies.