title: Nonradiative deactivation of excited hemicyanines studied with submolecular spatial resolution by time-resolved surface second harmonic generation at liquid-liquid interfaces.
abstract: The excited-state dynamics of aminostilbazolium dyes is known to be dominated by nonradiative deactivation through large-amplitude motion. In order to identify the coordinate(s) responsible for this process, the excited-state lifetimes of two dialkylaminostyryl-methylpyridinium iodides have been measured at liquid-liquid interfaces using time-resolved surface second harmonic generation. We found that the decay time of the excited-states of both compounds was increasing with the viscosity of the apolar phase, consisting of n-alkanes of varying length, but was unaffected by that of the polar phase, made of water/glycerol mixtures. This indicates that the nonradiative deactivation is associated with the twist of the dialkylaniline group, which is located in the apolar part of the molecule.
authors.affiliation: Department of Physical Chemistry, University of Geneva, Genève, Switzerland.
authors.forename: Gaelle
authors.initials: G
authors.lastname: Martin-Gassin
authors.forename: Diego
authors.initials: D
authors.lastname: Villamaina
authors.forename: Eric
authors.initials: E
authors.lastname: Vauthey
mesh_terms: D005456:Fluorescent Dyes / Q000737:chemistry*; D005990:Glycerol / Q000737:chemistry; D015394:Molecular Structure; D011726:Pyridinium Compounds / Q000737:chemistry*; D011806:Quinolinium Compounds / Q000737:chemistry*; D013237:Stereoisomerism; D013343:Styrenes / Q000737:chemistry*; D013499:Surface Properties; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: C558599:4-(4-(dibutylamino)styryl)-N-methylpyridinium iodide; C117641:4-(4-(dihexadecylamino)styryl)-N-methylquinolinium iodide; D005456:Fluorescent Dyes; D011726:Pyridinium Compounds; D011806:Quinolinium Compounds; D013343:Styrenes; D014867:Water; D005990:Glycerol