title: Gas phase infrared multiple photon dissociation spectra of positively charged sodium bis(2-ethylhexyl)sulfosuccinate reverse micelle-like aggregates.
abstract: The capability of infrared multiple photon dissociation (IRMPD) spectroscopy to gain structural information on surfactant-based supramolecular aggregates has been exploited to elucidate intermolecular interactions and local organization of positively charged sodium bis(2-ethylhexyl)sulfosuccinate (AOTNa) aggregates in the gas phase. A detailed analysis of the stretching modes of the AOTNa CO and SO(3)(-) head groups allows one to directly probe their interactions with sodium counterions and to gain insight in their organization within the aggregate. Similarities and differences of the IRMPD spectra as compared to the infrared absorption spectrum of micellized AOTNa in CCl(4) have been analyzed. They strongly suggest a reverse micelle-like organization of AOTNa charged aggregates in the gas phase. Apart from low-abundance fragmentation channels of the AOTNa (molecule) itself, the main dissociation pathway of singly charged surfactant aggregates is the loss of neutral surfactant molecules, while doubly charged aggregates dissociate preferentially by charge separation forming singly charged species. In both cases, decomposition leads to the formation of the most energetically stable charged fragments.
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Siena, Via Aldo Moro I-53100 Siena, Italy. gianluca.giorgi@unisi.it
authors.forename: Gianluca
authors.initials: G
authors.lastname: Giorgi
authors.forename: Leopoldo
authors.initials: L
authors.lastname: Ceraulo
authors.forename: Giel
authors.initials: G
authors.lastname: Berden
authors.forename: Jos
authors.initials: J
authors.lastname: Oomens
authors.forename: Vincenzo Turco
authors.initials: VT
authors.lastname: Liveri
mesh_terms: D004143:Dioctyl Sulfosuccinic Acid / Q000737:chemistry*; D005740:Gases / Q000737:chemistry*; D007834:Lasers; D008823:Micelles; D017785:Photons; D013055:Spectrophotometry, Infrared / Q000379:methods*
chemical_list: D005740:Gases; D008823:Micelles; D004143:Dioctyl Sulfosuccinic Acid