PubMed Health⌕ Search

Biomedical subjects

O Cheshnovsky

Publications and source records attributed to O Cheshnovsky.

5 recordsLinked to original sources
PubMed2005

Comment on "Characterization of excess electrons in water-cluster anions by quantum simulations".

The conclusion by Turi et al. (Reports, 5 August 2005, p. 914) that all experimental spectral and energetic data on water-cluster anions point toward surface-bound electrons is overstated. Comparison of experimental vertical detachment energies with their calculated values for (H2O)n- clusters with surface-bound and internalized electrons supports previous arguments that both types of clusters exist.

Comment↗
PubMed2004

Observation of large water-cluster anions with surface-bound excess electrons.

Anionic water clusters have long been studied to infer properties of the bulk hydrated electron. We used photoelectron imaging to characterize a class of (H2O)n- and (D2O)n- cluster anions (n </= 200 molecules) with vertical binding energies that are significantly lower than those previously recorded. The data are consistent with a structure in which the excess electron is bound to the surface of the cluster. This result implies that the excess electron in previously observed water-cluster anions, with higher vertical binding energies, was internally solvated. Thus, the properties of those clusters could be extrapolated to those of the bulk hydrated electron.

Journal Article↗
PubMed2004

Hydrated electron dynamics: from clusters to bulk.

The electronic relaxation dynamics of size-selected (H2O)n-/(D2O)n[25 </= n </= 50] clusters have been studied with time-resolved photoelectron imaging. The excess electron (ec-) was excited through the ec-(p)<--ec-(s) transition with an ultrafast laser pulse, with subsequent evolution of the excited state monitored with photodetachment and photoelectron imaging. All clusters exhibited p-state population decay with concomitant s-state repopulation (internal conversion) on time scales ranging from 180 to 130 femtoseconds for (H2O)n- and 400 to 225 femtoseconds for (D2O)n-; the lifetimes decrease with increasing cluster sizes. Our results support the "nonadiabatic relaxation" mechanism for the bulk hydrated electron (eaq-), which invokes a 50-femtosecond eaq-(p)-->eaq-(s(dagger)) internal conversion lifetime.

Journal Article↗
PubMed2003

Auger recombination and charge-carrier thermalization in Hg - n -cluster photoelectron studies.

Photoelectron spectra (PES) of Hg(-)(n) show strong dependence of spectral features on photon energy, i.e., peak tailing and band gap filling. This dependence suggests the existence of complex photoinduced processes in parallel with the direct photodetachment process. The "corrupted" PES, taken with intermediate photon energy, carry the signature of interband absorption followed by charge-carrier thermalization and Auger electron ejection in Hg(-)(n). These processes, so significant in the photophysics of bulk semiconductors and nanoparticles, have not yet been identified in clusters.

Journal Article↗