W. L. Fite

Atom‐Molecule Reaction D+H2 → HD+H Studied by Molecular Beams

Collisions between deuterium atoms and hydrogen molecules have been studied in a modulated crossed beam experiment. The relative signal intensity and the signal phase for product HD from reactive collisions allowed determination of both the angular distribution and HD mean velocity as a function of angle. From these a relative differential reactive scattering cross section in center‐of‐mass coordinates was deduced. The experiment indicates that reactively formed HD having little or no internal excitation, departs from the collision anistropically, with maximum amplitude 180° from the direction of the incident D beam in c.m. coordinates, which shows that the D–H–H reacting configuration is short‐lived compared to its rotation time. Nonreactive scattering of D by H2 was used to assign absolute values to the differential reactive scattering cross sections.

Excitation of Na D‐Line Radiation in Collisions of Sodium Atoms with Internally Excited H2, D2, and N2

Excitation of D‐line radiation in collisions of Na atoms with vibrationally excited N2, H2, and D2 has been studied in two modulated crossed beam experiments. In both experiments, the vibrational excitation of the molecules was provided by heating the molecular beam source to temperatures in the range of 2000–3000°K, which was assumed to give populations according to the Boltzmann expression. In the first experiment, a total rate coefficient was measured as a function of molecular beam temperature, with absolute calibration of the photon detector being made using the black body radiation from the heated molecular beam source. Since heating affects both the internal energy and the collisional kinetic energy, the first experiment could not determine the relative contributions of internal energy transfer vs collisional excitation. The second experiment achieved partial separation of internal vs kinetic energy transfer effects by using a velocity‐selected molecular beam. Using two simple models for the kineti...

Charge Transfer of N2+, O2+, and NO+ to Sodium Atoms at Thermal Energies

A steady‐state flowing afterglow system has been utilized to measure the two‐body rate coefficients for the charge‐transfer reactions of N2+, O2+, and NO+ to sodium atoms. The reactions of N2+ and O2+ are rapid with rate coefficients of approximately 5.8 and 6.7 × 10−10 cm3/sec, respectively, whereas the NO+ reaction is found to be an order of magnitude slower.

Charge Transfer of N2+ and O2+ with Sodium Atoms

Collisions of nitrogen and oxygen molecular ions with atomic sodium have been examined in a crossed‐beam experiment in which the ion energy range was from 25 to 200 eV. It was found that charge transfer occurs with cross sections in excess of 10−16 cm2 and that in both cases the energy dependence is that typical of accidental resonance charge transfer. Extrapolation of these cross sections to the thermal energy range suggests that the thermal‐energy charge‐transfer rates are about 5×10−11 cm3/sec with N2+ and about 8×10−11 cm3/sec for O2+.

Associative ionization of uranium atoms and oxygen molecules

The absolute cross section for the reaction U+O2→UO2++e has been remeasured in an experiment where a beam of U atoms from a tungsten oven passes through O2 gas at low pressure, and ions formed by the reaction are collected at one of two condenser plates on either side of the beam. Uranium atom density was determined from the time‐integrated uranium atom current, which was determined by terminating the beam in a plastic bag, the uranium mass contents of which were measured by neutron activation analysis. The finding is that the effective cross section for a beam‐through‐gas experiment is 4.01 (±0.55)×10−17 cm2, a factor of 2.39 higher than the value determined in an earlier experiment of Fite, Lo, and Irving, where the time‐integrated uranium atom current was measured by condensing the uranium on a plate and alpha particle counting of the condensate.

Temperature dependence of the dissociative ionization of CO2

Abstract The elecltron impact ionization of CO 2 as a function of temperature of the CO 2 up to 1500 K has been studied using modulated beam mass spectrometry. It is found that in this temperature range the cross section for forming the primary ion CO 2 + is temperature-independent, as is the cross section for forming C + . Formation of the fragment ions O + and CO + depends on temperature, however, with the former decreasing and the latter increasing with increasing temperature. The observations are understood in terms of the thermal population of certain vibrationally excited states of the CO 2 molecule and the experiments yields ratios of cross sections of the excited states to the ground state, for the production of the fragments.

Possibility of Observing the Magnetic Charge of an Electron

The Lorentz force law and Maxwells equations are extended to include magnetic as well as electric charges, by requiring that the equations be symmetrical in these charges. This extension predicts that the absolute magnetic charge of a particle cannot be detected. What can be detected are differences in magnetic charge between elementary particles and the validity of the assumed method of extending the Maxwell-Lorentz equations. An experiment is described which appears to measure the magnetic charge of an electron, but which instead bears on the form of the Maxwell-Lorentz equations. Other arguments limit the difference between proton and electron magnetic charges.

Lyman-Alpha Emission Induced by the Collisions of Electrons with Molecular Hydrogen

The ratio of electron‐impact cross sections of atomic and molecular hydrogen for production of uv radiation detected by an oxygen‐filtered iodine‐vapor‐filled photon counter has been precisely measured in a modulated beam experiment. Using a filter 1.67 cm long with an oxygen pressure of 1 atm, the ratio of cross sections at 100 eV was found to be 4.05 ± 0.07. Using the known cross section for production of Lyman‐alpha radiation from the hydrogen atom, the cross section for molecular radiation received by the detector was determined to be 1.48 (± 0.05) × 10−17 cm2.

Reactions between NO+ and metal atoms using magnetically confined afterglows

A new method of studying thermal energy ion–neutral collision processes involving nongaseous neutral atoms is described. A long magnetic field produced by a solenoid in a vacuum chamber confines a thermal‐energy plasma generated by photoionization of gas at very low pressure. As the plasma moves toward the end of the field, it is crossed by a metal atom beam. Ionic products of ion–atom reactions are trapped by the field and both the reactant and product ions move to the end of the magnetic field where they are detected by a quadrupole mass filter. The cross sections for charge transfer between NO+ and Na, Mg, Ca, and Sr and that for rearrangement between NO+ and Ca have been obtained. The charge‐transfer reaction is found strongly dominant over the arrangement reaction that forms metallic oxide ions.