Biomedical subjects

J R R Verlet

Publications and source records attributed to J R R Verlet.

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

Optical control of the rotational angular momentum of a molecular Rydberg wave packet.

An intuitive scheme for controlling the rotational quantum state of a Rydberg molecule is demonstrated experimentally. We determine the accumulated phase difference between the various components of a molecular electron wave packet, and then employ a sequence of phase-locked optical pulses to selectively enhance or depopulate specific rotational states. The angular momentum composition of the resulting wave packet, and the efficiency of the control scheme, is determined by calculating the multipulse response of the time-dependent Rydberg populations.

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PubMed2002

Controlling the angular momentum composition of a Rydberg electron wave packet.

Sequences of phase-locked laser pulses have been employed to control the orbital angular momentum character of an electron wave packet, which is initially created from a superposition of s and d Rydberg series. By an intelligent choice of phase, which depends on the excitation energy and the quantum defects, we are able to selectively pump down either all or a fraction of one or other angular momentum component, and by employing multichannel quantum-defect theory we are able to analyze the quantum-state distribution in detail.

Journal Article↗