title: Ultrafast energy migration pathways in self-assembled phospholipids interacting with confined water.
abstract: Phospholipids self-assembled into reverse micelles in benzene are introduced as a new model system to study elementary processes relevant for energy transport in hydrated biological membranes. Femtosecond vibrational spectroscopy gives insight into the dynamics of the antisymmetric phosphate stretching vibration ν(AS)(PO(2))(-), a sensitive probe of local phosphate-water interactions and energy transport. The decay of the ν(AS)(PO(2))(-) mode with a 300-fs lifetime transfers excess energy to a subgroup of phospholipid low-frequency modes, followed by redistribution among phospholipid vibrations within a few picoseconds. The latter relaxation is accelerated by adding a confined water pool, an efficient heat sink in which the excess energy induces weakening or breaking of water-water and water-phospholipid hydrogen bonds. In parallel to vibrational relaxation, resonant energy transfer between ν(AS)(PO(2))(-) oscillators delocalizes the initial excitation.
authors.affiliation: Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, D-12489 Berlin, Germany. levinger@lamar.colostate.edu
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Levinger
authors.forename: Rene
authors.initials: R
authors.lastname: Costard
authors.forename: Erik T J
authors.initials: ET
authors.lastname: Nibbering
authors.forename: Thomas
authors.initials: T
authors.lastname: Elsaesser
mesh_terms: D004735:Energy Transfer; D008823:Micelles; D015394:Molecular Structure; D010743:Phospholipids / Q000737:chemistry*; D013816:Thermodynamics; D014732:Vibration; D014867:Water / Q000737:chemistry*
chemical_list: D008823:Micelles; D010743:Phospholipids; D014867:Water