Measurements at room temperature of the drift velocity, the longitudinal diffusion coefficient, and the transverse diffusion coefficient have been made for low-energy mass-identified nitrogen ions in nitrogen gas in a drift-tube mass spectrometer. These parameters were evaluated using an analysis described in the article immediately preceding this one. The mobilities of N+ and N2+ were obtained over the E/N range from 7 to 700 x 10 V cm, yielding zero-field reduced mobility values of 2.97 and 1.87 cm /V sec, respectively. The mobilities of N3+ and N4 were obtained over the E/N range from 2 to 40 x 10 V cm, yielding zero-field reduced mobility values of 2.26 and 2.33 cm /V sec, respectively. For N+ and N2+, the longitudinal diffusion coefficients were determined from the widths of the expeximental arrival time spectra, and the transvexse diffusion coefficients were determined from the attenuation of the ion count rate as the drift distance was increased. For both ions the two diffusion coefficients were observed to be equal and in agreement with the Einstein relation at low E/N, but to behave quite differently as E/N was increased. It has previously been reported that the longitudinal diffusion coefficients of both ions increase rapidly by more than an order of magnitude; the transverse diffusion coefficient of N+ has been found to increase in a similar fashion, although much less rapidly, while that of N~+ remains nearly constant, Measuxements were made up to an E/N of 700 & 10 V cm . The rates of the two ion-molecule reactions, N++2N~N3++N2 and N2 +2N& N4 +N2, were also measured by an attenuation technique over the E/N range from thermal to 100 x 10 V cm . The reaction rates at thermal energy were determined to be 1.8 && 10 cm /sec and 5.0 x 10 cm /sec, respectively, and both rates were observed to decrease as E/twas increased. I. INIODUCTIONThis article presents the results of an extensive investigation of the drift, diffusion, and reaction of lom-energy nitrogen ions in nitrogen gas at room temperature.The data mere obtained with a drift-tube mass spectrometer of ultra-highvacuum construction. Using an analysis discussed in the preceding paper, ' the mobilities of N+, N, +, N, , and N~i ons in nitrogen gas have been determined, both the longitudinal (Dl ) and the transverse (DZ ) diffusion coefficients of N and N, + have been measured, ' and the reaction-rate coefficients for the three-body ion-molecule reactions have been evaluated.The mobility K is defined' as the ratio of the drift velocity e~t o the electric field strength E, and is inversely proportional to the gas numbex density ¹ To facilitate comparisons of data obtained at different gas number densities, we shall make use of the "reduced mobility" II"» defined by the equation where p and 7. " are the gas pressure and temperature, in Torr and deg Kelvin, respectively, at which the measurement of K was made. At a given temperature T, the parameter E/N determines the average energy and the transport properties of the ions. Hence the data are present...

A multistate Landau–Zener method is set up for the calculation of atomic ion–ion mutual neutralization total cross sections. The results of the calculations are compared with experimental results for O++O−, N++O−, He++D−, He++H−, and H++H−. The energy range scanned depends on the system but varies between about 0.1 and 10 000 eV. The agreement between theory and experiment is usually within a factor of 2.

No abstract

Photofragment energy distributions have been measured for the process Ar+2(2Σ+u)+hν→Ar++Ar using a 3 keV ion beam and cw lasers both coaxial and crossed with the ion beam, polarized, respectively, perpendicular and parallel to the ion beam direction. Measurements were made at 14 wavelengths between 4579 and 7993 Å. Transitions to the dissociative states 2Πg and 2Σ+g are observed, as are the effects of the spin–orbit interaction in Ar+2. The experimental results are used along with theoretical calculations to determine the 2Σ+u, 2Σ+g, and 2Πg potentials. The effects of the spin–orbit interaction on the potential curves, the magnitude and wavelength dependence of the photodissociation cross section, and the angular distributions of the photofragments are considered.