J.L. Gardner

Total and partial photoionization cross-sections of O2 from 100 to 800 Å

Abstract The branching ratios and absolute values of the total and partial photoionization cross-sections for producing O 2 + in its various electronic states are given as a function of wavelength in the range 100–800 A. Cross-sections for dissociative ionization are given based on the premise that some of the bound ionic states predissociate. Photoelectron spectroscopy and absorption techniques utilizing a double ionization chamber were used to obtain the data.

Total and partial photoionization cross sections of N2 from threshold to 100 AA

The total photoionization cross section of N2 has been obtained from the ionization threshold to 100 AA with an accuracy of +or-3%. In addition, partial photoionization cross sections for transitions into the x2 Sigma g+, A2 Pi u and B2 Sigma u+ electronic states have been measured using the technique of photoelectron spectroscopy over the wavelength range from 745 to 304 AA. Transitions to higher electronic states are also observed at 304 AA.

Partial photoionization cross-sections and branching ratios of CO from 750 to 304 Å

Abstract The absolute values of the partial photoionization cross-sections and branching ratios for producing carbon monoxide ions in their X 2 Σ + , A 2 Π, B 2 Σ + and 2 Σ + (σ2s) states have been obtained as a function of wavelength from the A 2 Π ionization threshold to 304 A. Results have been obtained within autoionizing resonances as well as within the photoionization continuum.

Photoion and photoelectron spectroscopy of CO and N2

Dissociative photoionization processes in CO and N2 have been studied via photoion and photoelectron spectroscopy. Kinetic energy spectra of both the ions and electrons formed in CO and N2 have been recorded with a calibrated energy analyzer at incident wavelengths of 584, 462, and 304 A. The 304 A spectra are correlated in energy and intensity to deduce dissociation products. For CO, the 2Σ+ state of CO+ formed by removing a σ2s electron dissociates to the products C+ (2p 2P0) and O (3s′ 3D0). The N2 ion and electron spectra at 304 A both contain evidence for dissociative transitions involving the D 2Πg state of N2+. Energetic N+ ions produced upon removal of a σg2s electron are best explained by a dissociation limit of N+ (2p3 3P0) and N (2p3 4S0).

Branching Ratios in Photoelectron Spectroscopy

The problem of measuring branching ratios or transition probabilities using the technique of photoelectron spectroscopy is discussed in terms of the angular distribution of the ejected photoelectrons. Equations are developed that can be used in conjunction with any type of electron-energy analyzer to correct for any discrimination in the analyzer caused by electrons of varying angular distribution. Results are presented for the branching ratios of the A2IIu and B2∑u+ states of CO2+ produced by 584 A and obtained by a variety of electron-energy analyzers.

Vibrational intensity distributions for the various electronic states of O2+, N2+ and CO+ produced by photoionization

Abstract The vibrational intensity distributions produced by the process of photoionization are tabulated as a function of wavelength between 745 and 304 A for all major electronic states of O 2 + , N 2 + and CO + . The technique of photoelectron spectroscopy was used with an electron energy analyzer of known luminosity.

Photoion and photoelectron spectroscopy of oxygen

Photoion and photoelectron kinetic energy distributions of O2 have been measured at a number of incident monochromatic wavelengths extending down to 304 A. By correlating energies and intensities in the ion and electron spectra at each wavelength, dissociation limits are assigned for the 2Πu(III), cu20094Σ−u, and 4Σg(σg2s) molecular states of O2+. Other processes are suggested to explain the remaining peaks appearing in the photoion spectra.

Fluorescent cross sections and yields of CO2+ from threshold to 185 Å

The absolute cross sections and yields for the production of fluorescent radiation from the Au20092Πu and Bu20092Σu+ states of CO2+ induced by photoionization of neutral CO2 are presented for the spectral range 716 A (threshold) to 185 A. In addition fluorescent radiation between 1040 and 1600 A was observed in the spectral range below 400 A. This short wavelength fluorescence is discussed in terms of dissociative processes.

Collecting efficiency of a cylindrical mirror electron energy analyzer with pre-retarding lens

The electron collecting efficiency of a cylindrical mirror energy analyzer incorporating retardation of the electrons prior to analysis has been determined over the range 0 to 30 eV by two methods. The first method requires the use of a vacuum ultraviolet monochromator to produce monoenergetic electrons of different energies; the second method involves measuring the energy-brightness relationship of the retarding optics and should be applicable to any deflection analyzer with pre-retarding optics. The results of the two methods are compared and the limitations of the latter method are discussed.

Photoelectron spectroscopy of N2 and CO with dispersed Nel radiation

Abstract High resolution photoelectron spectra have been recorded from N 2 and CO with a fully calibrated energy analyzer at both the 736 and 744 A Nel lines. Observation of electrons from transitions to the υ = 11 level of the CO + X 2 Σ + ground state is reported for the first time. Relative intensities of all vibrational peaks appearing in each spectrum are given.