M. Skibowski

Optical absorption of gaseous methane, ethane, propane and butane and reflection of solid methane and ethane in the vacuum ultraviolet

Abstract The absorption spectra of gaseous n-alkanes have been investigated for photon energies from 8 to 35 eV where excitations of the σ electrons are expected to occur. For methane and ethane the spectra are compared to reflectance measurements on solid films. A new monochromator designed for work with synchrotron radiation and a windowless absorption cell made it possible to resolve considerable new structures.

High resolution monochromator for the VUV radiation from the DORIS storage ring

The unique properties of the DORIS storage ring at DESY as a synchrotron radiation source are exploited for high resolution spectroscopy in the vacuum ultraviolet. We describe a new experimental set up with a 3-m normal incidence monochromator for wavelengths between 3000 A and 300 A (4 </= ?w </= 40 eV) using a vertical dispersion plane. The storage ring provides a light flux intense and stable enough for rapid photoelectrical scanning of the spectra with a resolution of 0.03 A in first order.

Vacuum ultraviolet reflectivity of solid nitrogen and oxygen

Abstract The reflectance of solid nitrogen and oxygen has been measured at a 15° angle of incidence from 10 to 23 eV at temperatures below 10°K using synchrotron radiation. The observed transitions are compared to molecular excitations.

Photoelectric yield of the potassium halides in the photon energy range 10 to 35 eV

Abstract The spectra of the relative photoelectric yield of thin films of all potassium halides have been measured with the synchrotron radiation of DESY. The spectra exhibit two broad maxima at about 12 to 18 and 25 eV which are discussed in terms of electron-electron scattering. Superimposed is a fine structure which generally corresponds to the optical spectra and is interpreted as excitonic and interband transitions from the valence band and K+3p core level.

Electronic excitation of solid carbon dioxide in the extreme ultraviolet

Abstract The reflection spectrum of solid CO 2 has been measured for 30°K at 15° angle of incidence from 10 to 30 eV using synchrotron radiation. The e 2 -spectrum was calculated by means of the dispersion relation. The observed electronic absorption bands are compared to molecular excitations.

Photoemission from solid neon

Abstract The photoelectric yield of solid Ne has been studied for photon energies between 15 and 30 eV. Strong photoemission from the valence band sets in at 21.4 ± 0.1 eV. The value of the electron affinity derived from this is discussed. A surface resonance for Ne atoms adsorbed on gold is observed at 17.1 eV.

Optical excitation of the Rb+ 4p-level in rubidium halides at 8 K☆

Abstract In the 15–19 eV range new spectral features have been resolved in the reflection spectra of RbCl, RbBr, and RbI single crystals. They are not entirely consistent with results of a recently proposed ligand field model for the Rb+4p- excitons.

Plasma resonance in the reflection spectrum of thin aluminium films

Abstract The reflectance of thin Al fims has been measured near the plasma wavelength (840 A) at a pressure of 2 × 10−9 Torr using synchrotron radiation as light source. For parallel-polarized light a plasma resonance maximum was found together with a Brewster minimum.

Excitation of the Cs-5p core level in Cs halides

Abstract New electronic transitions from the Cs + 5p core level were found for all Cs halides by studying their reflection spectra for photon energies between 10 and 30 eV using synchrotron radiation.

Exciton Contribution to the Photoemission from Thin Films of Solid Argon

The photoelectric yield and the reflectance of solid Ar films on an Au substrate have been measured simultaneously for photon energies 10–30 eV. The thickness ranged from 30–300 A. The synchrotron radiation of DESY was used as a light source. Even at photon energies below the photoelectric threshold of solid Ar there is some photoemission due to contributions from both the Ar film and the gold substrate. The spectra of the yield per absorbed photon exhibit peaks at the exciton energies. The height of the peaks is almost independent of the film thickness. This indicates that exciton decay at the Ar-vacuum or Ar–Au boundary contributes to photoemission.