Ausma Skerbele

Intensity Distribution in the Electron‐Impact Spectrum of Carbon Monoxide at High‐Resolution and Small Scattering Angles

An electron spectrometer, which provides velocity selection before scattering, is described; and the results of a study of relative intensities in the carbon monoxide spectrum are reported. The vibrational levels of the fourth positive band system have been resolved and relative intensities determined for the first nine. The relative intensities are compared with calculated Franck—Condon factors. The agreement is good at low vibrational quantum numbers but noticeable discrepancies are found for high‐vibrational levels.The problem of calculating relative oscillator strengths from a fully resolved spectrum is considered and applied to data obtained in the present research. Relative oscillator strengths are compared with those obtained previously from unresolved spectra.If the Born approximation is valid, then the electron‐impact and ultraviolet absorption spectra should be closely similar. This is actually observed for most of the spectrum but the transition at 12.79 V is an outstanding exception. The relat...

The electronic structure of pyridine

Abstract The electron configuration of pyridine is deduced theoretically from the electron configuration of benzene, given in an earlier paper, under the condition that it must fit the photoelectron spectroscopy studies of pyridine by Turner. The electron configuration is then tested experimentally in applications on the vibrational structure of the photoelectron spectrogram, on the mass spectrum and on the electron impact energy loss spectrum. The study can be considered as a support for the earlier interpretation of the electronic structure of benzene.

Quadrupole‐Allowed Transitions in the Electron‐Impact Spectrum of N2

The forbidden transitions observed in the nitrogen spectrum below 12.5 V have been studied by electron‐impact methods. Since the theory indicates that electric quadrupole transitions are preferred to singlet—triplet in electron‐impact spectra at intermediate energies, the observed transitions are probably electric quadrupole allowed. This has been demonstrated for the 12.25‐V transition by studying its relative intensity as a function of the scattering angle. The data on the 11.86‐V transition are also compatible with an electric quadrupole transition. In addition, new data on the Lyman—Birge—Hopfield bands in the 60–400‐V energy range indicate that the intensity distribution among vibrational levels is independent of energy.

RELATIVE INTENSITIES OF TWO RYDBERG TRANSITIONS IN THE ELECTRON-IMPACT SPECTRUM OF WATER

The electron‐impact spectrum of water has been determined using a higher‐resolution electron spectrometer. The intensity distribution of five peaks in the spectrum which belong to two different Rydberg transitions has been investigated at zero scattering angle and electron kinetic energy of 200 V. Quantities proportional to the optical oscillator strengths for these excitations have been compared with absorption coefficients from ultraviolet spectra. The entire electron‐impact spectrum in the region below the first ionization potential shows good agreement with ultraviolet absorption.

Intensity Variation with Scattering Angle of Electronic Transitions in H2O Excited by Electron Impact

Electron‐impact spectra of water vapor have been investigated at 400‐ and 500‐V electron kinetic energy. The relative intensities of the five peaks associated with the A and B Rydberg transitions have been studied as a function of the scattering angle. The results suggest a new method of identification of vibrational levels where a high‐resolution study of rotational structure is not feasible.