Delayed dissociation of photoexcited porphyrin cations in a storage ring: determination of triplet quantum yields.
A technique is described wherein substituent-dependent excited-state properties of gas-phase porphyrins can be accurately quantified. Dissociation lifetimes of photoexcited porphyrin cations were measured in an electrostatic ion storage ring. From these data, upper limits for the triplet quantum yield of the following protonated porphyrins were obtained: protoporphyrin IX (0.63 +/- 0.04), tetraphenylporphyrin (0.73 +/- 0.03), tetra(p-methylphenyl)porphyrin (0.75 +/- 0.03), and tetra(p-cyanophenyl)porphyrin (0.71 +/- 0.03). The values compare well with those for porphyrins in solution.
Nielsen
Christian B
CB
Polymer Department, Risø National Laboratory, Frederiksborgvej 399, DK-4000 Roskilde, Denmark.
Forster
James S
JS
Ogilby
Peter R
PR
Nielsen
Steen Brøndsted
SB
D002412:Cations; D002627:Chemistry, Physical / Q000379:methods*; D006371:Helium / Q000737:chemistry; D007477:Ions; D008027:Light; D008956:Models, Chemical; D010100:Oxygen / Q000737:chemistry; D010777:Photochemistry / Q000379:methods; D017785:Photons; D011166:Porphyrins / Q000737:chemistry*; D011789:Quantum Theory; D026082:Singlet Oxygen / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D013997:Time Factors
D002412:Cations; D007477:Ions; D011166:Porphyrins; D026082:Singlet Oxygen; D006371:Helium; D010100:Oxygen