Photoionization efficiency curves were measured for gas-phase PtC, PtO, and PtO2 using tunable vacuum ultraviolet (VUV) radiation at the Advanced Light Source. The molecules were prepared by laser ablation of a platinum tube, followed by reaction with CH4 or N2O and supersonic expansion. These measurements provide the first directly measured ionization energy for PtC, IE(PtC) = 9.45 +/- 0.05 eV...

8-Oxoguanine is one of the key products of indirect radiation damage to DNA by reactive oxygen species. Here, we describe ionization of this damaged nucleobase and the corresponding nucleoside and nucleotide in aqueous phase, modeled by the nonequilibrium polarizable continuum model, establishing their lowest vertical ionization energies of 6.8-7.0 eV. We thus confirm that 8-oxoguanine has even...

The ultrafast transfer of excitation energy from one atom to its neighbor is observed in singly charged argon dimers in a time-resolved extreme ultraviolet (XUV)-pump IR-probe experiment. In the pump step, bound 3s-hole states in the dimer are populated by single XUV-photon ionization. The excitation-energy transfer at avoided crossings of the potential-energy curves leads to dissociation of th...

The single ionization of inner-shell electrons by electron or positron impact are the fundamental processes, which still attract considerable interest in collision theory, experimental studies, and various applications. To predict the ionization cross sections, one usually employs either sophisticated numerical approaches or empirical and semiempirical formulas. Significant efforts have been al...

A new detection method for obtaining collisional transition probabilities P(E',E) of highly vibrationally excited molecules in the gas phase is presented. The technique employs energy-selective probing of the time-dependent vibrational population distribution by "kinetically controlled selective fluorescence (KCSF)". We present experimental results for a test system, the collisional deactivatio...

The double 1s ionization of Si induced in collisions with protons and heavier ions (C, Ne) was studied by measuring the K X-ray emission of a solid Si target. In order to resolve the hypersatellite contributions in the spectra, high-resolution crystal diffractometry was employed yielding subelectronvolt energy resolution. Experimentally obtained hypersatellite yields were used to determine the ...

Cross sections for single electron-impact ionization of formic acid (HCOOH) and acetic acid (CH3–COOH) are calculated using the binaryencounter-Bethe model in the energy range from the ionization threshold up to 4000 eV. The present results are compared with available experimental and theoretical data.

A novel technique has been developed to build vessels for liquid xenon ionization detectors entirely out of ultra-clean fluoropolymer. We describe the advantages in terms of low radioactivity contamination, provide some details of the construction techniques, and show the energy resolution achieved with a prototype all-fluoropolymer ionization detector.

Helium and other atoms can, in principle, become doubly ionized when exposed to an intense laser pulse through two different channels: a direct process whereby both electrons are ejected simultaneously from the atom and a sequential process whereby the second charge state is created only after the first charge state. Crance and Aymar [1] calculated for He that if the number of photons required ...