Showing papers by "Fred L. Walls published in 1974"

Measurement of total cross sections for electron recombination with NO+ and O2 + using ion storage techniques

Abstract: The total cross section as a function of electron energy for recombination of electrons with room temperature NO+ has been measured with a trapped ion technique. Measurements were made in the electron energy range 0.045–4 eV with an energy resolution between 0.045 and 0.120 eV, and the cross sections, which showed some structure, ranged from 1.25 × 10−14 cm² at the lowest energy to 1.7 × 10−16cm² at the highest energy. Similar measurements were made on O2+, the species used to calibrate the apparatus geometry. A Maxwellian distribution of electron velocities was used with the measured cross sections to calculate rate constants, giving values extending to electron temperatures as high as 40,000°K. Comparison with previously measured rate coefficients at lower temperatures is quite satisfactory.

Storing ions for collision studies

Abstract: A static trap capable of storing ions for many hours—electrons for over a month—bids fair to bring the convenience of the chemist's reagent shelf to the study of ions and their interactions. The trap to store heavy ions developed at the Joint Institute of Laboratory Astrophysics, shown on the cover and in figure 1, is preferable for our work to its older cousin, the radiofrequency trap, in that it does not feed energy into the system it contains. Its usefulness is further enhanced by a nondestructive detection technique. Thus ends the era when our knowledge of ions and their interactions depended exclusively on analysis of plasmas, laboratory and natural, or the cleaner method of colliding beams.