Synchrotron radiation from the German storage ring BESSY has been used to study the photoelectron spectrum of the water molecule. Asymmetry parameters and relative photoionization cross sections have been measured for all four molecular orbitals (2a1, 1b2, 3a1, and 1b1) in the 30–140 eV photon energy range. The results have been compared with the Xα calculations of Roche, Salahub, and Messmer and good agreement was found. Comparison was also made with a number of previous measurements, including those obtained by (e,2e) spectroscopy. Finally, the inner valence (2a1) region has been studied at 60 and 100 eV photon energies and the relative intensities of some of the satellites were found to change as the exciting energy was varied.

The core binding energies of glycine vapor have been measured by X-ray photoelectron spectroscopy. The values obtained are C Is (methyl carbon) 292.25 (10), C Is (carboxyl carbon) 295.15, O Is (keto O) 538.2, O Is (hydroxyl O) 540.0, and N Is 405.58 eV. Comparison is made with related molecules such as acetic acid and methylamine. Using proton affinity-binding energy correlations from the literature, we have calculated proton affinity (PA) values for keto oxygen and nitrogen protonation and have found good agreement with the PA measured by other techniques. Combining known gas-phase acidities with core binding energies shows that the increase in acid strength in going from acetic acid to glycine to benzoic acid is primarily due to the ability of the residual ion to delocalize the charge created by the removal of the proton.

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Photoemission spectra of the second-row hydrides CH4, NH3, H2O, and HF, as well as Ne, obtained with ultrasoft (132.3 eV) x rays from the yttrium Mζ line and with soft x rays are compared and discussed. The 2s-derived 2a1 or 2σ orbitals show large relaxation energies, as do the 2s orbitals in the free atoms. The high binding energies of the 2a1 orbitals in CH4 and NH3 indicate that much of the bond energy resides in these orbitals. Bond energies estimated from changes in the average valence-electron binding energies from atoms to hydrides show rough agreement with literature values. Relative molecular orbital peak intensities show dramatic changes from 132.2 eV to 1253.6 eV photon energies, with the atomic cross-section ratio 2p/2s near unity at 132.3 eV and near 0.1 at 1253.6 eV. This difference allows peaks to be assigned to molecular orbitals in some cases by visual inspection, on the basis of atomic orbital composition. Comparison with theoretical intensities based on plane-wave or OPW continum final states shows qualitative agreement at best, and clear disagreement in some cases. Quantitative agreement will require a more sophisticated theory. Values of σ (2p)/σ (2s) for atomic C, N, O, F, and Ne were derived from the spectra at both photon energies.