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Calibration of a monochromator/spectrometer system for the measurement of photoelectron angular distributions and branching ratios
We describe the techniques used in calibrating a monochromator/spectrometer system for gas-phase photoelectron angular distribution and branching ratio measurements. We report a self-consistent set of values for the Ne 2p, Ar 3p, Kr 4p/sub 3/2/ and 4p/sub 1/2/, and Xe 5p/sub 3/2/ and 5p/sub 1/2/ photoelectron asymmetry parameters and for the Kr 4p/sub 3/2/:4p/sub 1/2/ and Xe 5p/sub 3/2/:5p/sub 1/2/ branching ratios for the energy regions from threshold to approximately 15 iV. 22 refs., 7 figs
A STUDY OF VIBRONIC COUPLING IN THE [MATH] STATE OF CO+2
Les effets du couplage vibronique dans l'état [MATH](2∑g+) du CO2+ ont été étudiés pour des photons d'énergies comprises entre 20 et 28,5 eV. Deux analyseurs d'électrons hémisphériques suivis de détecteurs sensibles à la position combinés au rayonnement synchrotron de SURF-II ont permis un analyse vibrationnellement résolve de l'état [MATH](2∑g+). La distribution angulaire caractérisée par le paramètre β de l'état vibrationnel interdit [MATH](1,0,1) se révèle très différent de celle de l'état permis [MATH](0,0,0). Les similarités entre la distribution angulaire (β vs. hν) de l'état interdit [MATH](1,0,1) et celle de l'état [MATH](2∑u+) supportent l'hypothèse de couplage vibronique entre ces deux états comme origine pour la bande interdit.We have studied vibronic coupling in vibrationally resolved photoionization to the [MATH] (2∑g+) state of CO2+ in the photon-energy range hν=20-28.5 eV. The measurements utilize high-resolution hemispherical electron analyzers, equipped with area detectors, and the SURF-II synchrotron radiation source at the National Bureau of Standards. The angular distribution asymmetry-parameters (β) for the allowed [MATH](0,0,0) and forbidden [MATH](1,0,1) (19.747 eV binding energy) peaks are found to be quite different. However, similarities between the [MATH](1,0,1) β curve and that for the [MATH] state suggest that vibronic coupling to the [MATH] (2∑u+) state of CO2+ is the explanation for the intensity of the [MATH] state forbidden band in the first 8 eV above threshold