INVESTIGADORES
PINO Gustavo Ariel
artículos
Título:
Unexpected size distribution of Ba(H2O)n clusters: why is the intensity of the Ba(H2O)1 cluster anomalous low?
Autor/es:
I. CABANILLAS-VIDOSA; M. ROSSA; G. A. PINO *; J. C. FERRERO
Revista:
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
Editorial:
ROYAL SOC CHEMISTRY
Referencias:
Año: 2011 vol. 13 p. 13387 - 13394
ISSN:
1463-9076
Resumen:
An experimental and theoretical study on the reactivity of neutral Ba atoms with water clusters
has been conducted to unravel the origin of the irregular intensity pattern observed in one-photon
ionization mass spectra of a Ba(H2O)n/BaOH(H2O)n1 (n = 1?4) cluster distribution, which was
generated in a laser vaporization-supersonic expansion source. The most remarkable irregular
feature is the finding for n = 1 of a lower intensity for the Ba+(H2O)n peak with respect to that
of BaOH+(H2O)n1, which is opposite to the trend for n = 2?4. Rationalization of the data
required consideration of a distinct behavior of ground-state and electronically excited state Ba
atoms in inelastic and reactive Ba + (H2O)n encounters that can occur in the cluster source.
Within this picture, the generation of Ba(H2O)n (n 4 1) association products results from
stabilizing collisions with atoms of the carrier gas, which are favored by intramolecular vibrational redistribution that operates on the corresponding collision intermediates prior to stabilization; the latter is unlikely to occur for Ba + (H2O) encounters. Overall, this
interpretation is consistent with additional in-source laser excitation and quenching experiments,
which aimed to explore qualitatively the effect of perturbing the Ba atom electronic state
population distribution on the observed intensity pattern, as well as with the energetics of various
possible reactions for the Ba + H2O system that derive from high level ab initio calculations.