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Title

Effect of Salt on the Excited-State Dynamics of Malachite Green in Bulk Aqueous Solutions and at Air/Water Interfaces: a Femtosecond Transient Absorption and Surface Second Harmonic Generation Study
Authors
Punzi, Angela
Gassin-Martin, Gaëlle
Grilj, Jakob
Vauthey, Eric
Published in Journal of Physical Chemistry. C. 2009, vol. 113, no. 27, p. 11822-11829
Abstract The ultrafast excited-state dynamics of Malachite Green (MG) in bulk aqueous solutions and at air/water interfaces, in particular the effect of the presence of various sodium salts in the aqueous phase, has been investigated by transient absorption and surface second harmonic generation. In bulk solutions, a slowing down of the ground-state recovery that can be unambiguously ascribed to the formation of aggregates of various sizes is observed at high (>0.3 M) salt concentrations only, with the exception of NaSCN where an effect is already found at 0.05 M. At the interface, small amounts of salt result in two effects: 1) an increase of the stationary surface second harmonic signal and 2) a slowing down of the ground-state recovery of MG. These phenomena are explained by the formation of aggregates due to an increase of the interfacial MG concentration upon addition of salt. The dependencies of both effects on salt concentration are correlated and vary with the anion as SCN− > Br− > SO4− > Cl−. This order is almost the opposite as that in the Hofmeister series for the salting-out strength.
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Structures
Faculté des sciences / Section de chimie et biochimie / Département de chimie physique
Research group Groupe Vauthey
Citation
(ISO format) 		PUNZI, Angela et al. Effect of Salt on the Excited-State Dynamics of Malachite Green in Bulk Aqueous Solutions and at Air/Water Interfaces: a Femtosecond Transient Absorption and Surface Second Harmonic Generation Study. In: Journal of Physical Chemistry. C, 2009, vol. 113, n° 27, p. 11822-11829. https://archive-ouverte.unige.ch/unige:3179

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Deposited on : 2009-09-21

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