E. Nõmmiste

Ti 2p and O 1s X-ray absorption of TiO2 polymorphs

Abstract We present and discuss the Ti 2p and O 1s X-ray absorption spectra (XAS) and resonant photoelectron emission spectra (RPES) of the various polymorphic forms (TiO2-II, rutile and anatase) of TiO2. The largest differences between the Ti 2p XAS of polymorphs of TiO2 are observed in the region of the double peak structure of the L3 edge. A strong delocalization of the excited 3d electron in this region is concluded from the RPES at the L3 threshold of Ti. The differences in XAS are attributed to increasing strength of the crystal field caused by delocalization of the excited 3d electron.

NEW END STATION FOR THE STUDY OF GASES, LIQUIDS, AND SOLID FILMS AT THE MAX LABORATORY

A new end station equipped with a very high‐resolution SES‐200 electron energy analyzer has been constructed for the study of gases and soft molecular materials. The analyzer is rotatable around the direction of the photon beam, allowing angular‐dependent studies. The system has been built in a way allowing the investigation of free molecules and atoms, metal vapors, liquid interfaces as well as solid films. The first electron spectroscopy results for gases, liquids, and polymer films are presented.

Auger decay of the dissociating core‐excited states in the HCl and DCl molecules

High‐resolution Auger electron spectra from the decay of the Cl 2p→σ* excitation in HCl and DCl have been measured. The spectra are analyzed, separating molecular and atomic features, which are assigned to transitions to the HCl (5σ2π)4σ* and Cl (3s3p)6 states, respectively. Auger line shapes, as affected by the molecular dissociation, are studied by comparing the experiment with the results of Monte‐Carlo computer simulations based on a semiclassical model.

FINNISH BEAMLINE AT MAX-LABORATORY - PROGRESS IN THE PHOTON ENERGY RESOLUTION

The photon energy resolution of the modified SX‐700 plane grating monochromator at the Finnish beamline (BL51) at MAX‐laboratory in Lund, Sweden, has improved considerably after proper alignment of the monochromator. Resolving powers of about 10 000 at hν≊90 eV and 5000 at hν≊400 eV have been achieved at the first diffraction order, as inferred from total ion yield measurements at the Kr 3d5/2→5p and N2 N1s→π* resonances. The total linewidth of ≤121 meV recorded for the Ar 2p3/2→4s excitation suggests that the lifetime broadening could be smaller than 116 meV obtained from electron energy‐loss spectroscopy.

FAST DISSOCIATION OF RESONANTLY CORE EXCITED H2S STUDIED BY VIBRATIONAL AND TEMPORAL ANALYSIS OF THE AUGER SPECTRA

Excitation of a core electron to the lowest unoccupied orbital of H2S has been shown to give rise to dissociation that occurs faster than the Auger decay. Recent experimental data have allowed us to resolve vibrational structures connected with the resona

Decay of the , and states of Ar studied by utilizing the Auger resonant Raman effect

The 2p electrons of Ar have been excited selectively to the 4s, 3d and 4d orbitals and high-resolution de-excitation spectra have been recorded by utilizing the Auger resonant Raman effect. Fine structures in the resonant Auger spectra have been clearly resolved for the first time. The roles of shake transitions and configuration interaction between the and , n = 3 - 6 final states in producing the complicated fine structures have been discussed.

Partial Auger decay rates of core-ionized molecular states in HCl and DCl

The Cl 2p ionization and the subsequent 2p-1 to 2 pi -2 Auger decay in HCl and DCl molecules have been studied using synchrotron radiation. The Auger spectra have been decomposed and assigned to the transitions from the 2 Pi 1/2, 2 Sigma 1/2 and 2 Pi 3/2 molecular states of the 2p core hole configuration. The 2 Sigma 1/2 and 2 Pi 3/2 states have been found to be separated by 79(8) meV (HCl) and 83(8) meV (DCl). The partial Auger decay rates from different core ionized states have been shown to differ considerably.

INTENSITIES OF THE XENON N4,5OO AUGER ELECTRON SPECTRUM REVISITED

Abstract The N 4,5 OO Auger spectrum of xenon has been measured at several photon energies using synchrotron radiation. Transmission corrected intensities of the Auger lines and groups are compared with the results of the Hartree–Fock and previously published Dirac–Fock calculations.

Correlation satellites in the Xe N4,5-OO and Kr M4,5-NN Auger spectra

Correlation satellite lines originating from the strong mixing between 5s15p5, 5s25p3nd (n=5, 6, 7, ...) and 5s25p3ms (m=6, 7, 8, ...) configurations in the final state of the N4,5-O1O2,3 Auger decay of Xe and between 4s14p5, 4s24p3nd (n=4, 5, 6, ...) and 4s24p3ms (m=5, 6, 7, ...) final-state configurations in the M4,5-N1N2,3 Auger decay of Kr have been studied by means of synchrotron-radiation excited electron spectroscopy and relativistic multiconfigurational Dirac-Fock calculations. Improvements in experimental and computational methods have made it possible, for the first time, to resolve and to assign most of the satellite lines with high accuracy.

Photoion spectra of C60 molecules at resonance excitation and ionization energies near the C 1s edge

Photoionization dynamics of gas-phase C60 molecules after selective excitation with synchrotron radiation has been studied with time-of-flight mass spectrometry. The energy level scheme deduced from previous photoelectron and Auger electron spectra is used to analyze the photoion data. At the vicinity of π* pre-edge resonances the fragmentation of multiply-charged ions varies strongly as a function of photon energy. The C60+ ion yield decreases slowly after 1s threshold indicating that the slow photoelectrons can get recaptured. Somewhat further above the threshold the enhanced relative fragmentation of the parent C60+ ions suggests excitation of the giant plasmon resonance due to 20 eV photoelectrons.