We report on an experimental and theoretical investigation of x-ray absorption and resonant Auger electron spectra of gas phase O(2) recorded in the vicinity of the O 1s-->sigma(*) excitation region. Our investigation shows that core excitation takes place in a region with multiple crossings of potential energy curves of the excited states. We find a complete breakdown of the diabatic picture for this part of the x-ray absorption spectrum, which allows us to assign an hitherto unexplained fine structure in this spectral region. The experimental Auger data reveal an extended vibrational progression, for the outermost singly ionized X (2)Pi(g) final state, which exhibits strong changes in spectral shape within a short range of photon energy detuning (0 eV>Omega>-0.7 eV). To explain the experimental resonant Auger electron spectra, we use a mixed adiabatic/diabatic picture selecting crossing points according to the strength of the electronic coupling. Reasonable agreement is found between experiment and theory even though the nonadiabatic couplings are neglected. The resonant Auger electron scattering, which is essentially due to decay from dissociative core-excited states, is accompanied by strong lifetime-vibrational and intermediate electronic state interferences as well as an interference with the direct photoionization channel. The overall agreement between the experimental Auger spectra and the calculated spectra supports the mixed diabatic/adiabatic picture.
Multiply charged Xe ions produced through photoionization of a
3d electron have been measured using the coincidence technique.
The coincidence measurement between the energy-selected Auger
electron and ions specifies the individual Auger decay channels
for the various multiply charged ions. It has been found that
only quadruply charged ions are formed through the Auger decays
of M45N45N45 type. The M45N23N45
Auger decays predominantly yield Xe5+. These findings
indicate that most Xe ions produced through the initial
M45 Auger transitions turn into the highest charge state
between energetically accessible states through subsequent
successive Auger decays. However, in the M45N1N45
and M45N23N23 decays the intensity ratio of
Xe5+ with Xe6+ depends on the energy level of the
Auger final states. The highly charged ions, Xe7+ and
Xe8+, are produced through the initial Auger shake
processes from the 3d hole states.
Dedicated to the distinguished contributions to soft x-ray
photochemistry research by Professor Inosuke Koyano of the Himeji
Institute of Technology on the occasion of his 65th birthday.
Rate constants for the reactions of CH(X2Π : v = 0,1) with NO and O2 are measured under pseudo-first-order conditions at 297 ± 5 K. CH(X2Π : v = 0,1) radicals are generated by excimer laser photolysis of CHBr3 and (CH3)2 CO at 193 nm, and detected by the laser-induced fluorescence (LIF) technique. The overall rate constants obtained at the total pressure of 20 Torr Ar are: kNO(v = 0) = (1.6 ± 0.2) × 10−10, kNO(v = 1) = (1.3 ± 0.6) × 10−10, kO2(v = 0) = (3.5 ± 0.3) × 10−11, and kO2(v = 1) = (3.4 ± 0.8) × 10−11 (cm3 molecule−1 s−1).
No apparent pressure dependence is indicated for the rate constants over the pressure range of 5—50 Torr Ar for CH + NO, and 5—30 Torr Ar for CH + O2 reactions, respectively.
The reaction mechanisms are discussed based on the quantum mechanical calculations of the potential energy surfaces of CH + NO and CH + O2 systems.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.