title: Quantum yields of triplet and O2(1 delta g) formation of 4-thiouridine in water and acetonitrile.
abstract: The quantum yield of triplet formation, phi T, and that of the photosensitized formation of singlet molecular oxygen, phi delta, were determined for a rare nucleoside, 4-thiouridine (4t-Urd), in water and in acetonitrile, using singlet molecular oxygen phosphorescence, laser-induced optoacoustics and time-resolved thermal lensing. These yields, phi T and phi delta, the latter in aerated solutions, were found to be, respectively, in water: 0.67 +/- 0.17 and 0.18 +/- 0.04 and in acetonitrile: 0.61 +/- 0.15 and 0.50 +/- 0.20. The fraction of the 4t-Urd triplet molecules quenched by oxygen leading to singlet molecular oxygen, S delta, was calculated to be between 0.7 and unity in both solvents, this value being indicative of a pi pi*character for the lowest triplet state of 4t-Urd.
authors.affiliation: Max-Planck-Institut für Strahlenchemie, Mülheim a.d. Ruhr, W. Germany.
authors.forename: K
authors.initials: K
authors.lastname: Heihoff
authors.forename: R W
authors.initials: RW
authors.lastname: Redmond
authors.forename: S E
authors.initials: SE
authors.lastname: Braslavsky
authors.forename: M
authors.initials: M
authors.lastname: Rougée
authors.forename: C
authors.initials: C
authors.lastname: Salet
authors.forename: A
authors.initials: A
authors.lastname: Favre
authors.forename: R V
authors.initials: RV
authors.lastname: Bensasson
mesh_terms: D000097:Acetonitriles; D049449:Luminescence; D010100:Oxygen; D010777:Photochemistry; D011789:Quantum Theory; D026082:Singlet Oxygen; D013891:Thiouridine; D014867:Water
chemical_list: D000097:Acetonitriles; D014867:Water; D013891:Thiouridine; D026082:Singlet Oxygen; D010100:Oxygen; C032159:acetonitrile