TY - JOUR
T1 - Nitroxyl free radical enhancement of the forbidden O2(3Σ-g) ← O2(1Δg) radiative transition in chlorinated hydrocarbon solvents
AU - Belford, R. E.
AU - Seely, G.
AU - Gust, D.
AU - Moore, Thomas
AU - Moore, Ana
AU - Cherepy, N. J.
AU - Ekbundit, S.
AU - Lewis, J. E.
AU - Lin, S. H.
N1 - Funding Information:
This is publication #106 from the Arizona State University Center for the Study of Early Events in Photosynthesis. The Center is funded by the U.S. Department of Energy, grant #DE-FGOZ-88ER13969, as part of the USDA/DOE/NSF Plant Science Center program.
Funding Information:
This work was supported in part by grants to D.G. and T.A.M. (CHE-8903216) and to S.H.L. (CHE-9114974) from the National Science Foundation.
PY - 1993/2/15
Y1 - 1993/2/15
N2 - Utilizing transient near-IR luminescence spectroscopy, we have shown that free radicals like TEMPO (2,2,6,6- tetramethylpiperidine-N-oxyl) increase the rate of the forbidden radiative transition of singlet oxygen in chlorinated hydrocarbon solvents. The quantum yield for emission has been shown to depend on the nature of the substituent group in the 4′ position. Concomitant with this effect is a slight high energy shift in the steady state singlet oxygen phosphorescence spectrum. Additional experiments with TEMP (2,2,6,6-tetramethylpiperidine) have shown that the nitroxyl group is necessary for this effect. Using the kinetic equations associated with a collision complex model, we have investigated a curve crossing (isophotic) point observed in the 1270 nm luminescence decays at various TEMPO concentrations. This information indicates that we are observing a contact complex characterized by a weak interaction energy and a short lifetime. We have also determined the conditions under which the isophotic point can be observed.
AB - Utilizing transient near-IR luminescence spectroscopy, we have shown that free radicals like TEMPO (2,2,6,6- tetramethylpiperidine-N-oxyl) increase the rate of the forbidden radiative transition of singlet oxygen in chlorinated hydrocarbon solvents. The quantum yield for emission has been shown to depend on the nature of the substituent group in the 4′ position. Concomitant with this effect is a slight high energy shift in the steady state singlet oxygen phosphorescence spectrum. Additional experiments with TEMP (2,2,6,6-tetramethylpiperidine) have shown that the nitroxyl group is necessary for this effect. Using the kinetic equations associated with a collision complex model, we have investigated a curve crossing (isophotic) point observed in the 1270 nm luminescence decays at various TEMPO concentrations. This information indicates that we are observing a contact complex characterized by a weak interaction energy and a short lifetime. We have also determined the conditions under which the isophotic point can be observed.
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U2 - 10.1016/1010-6030(93)85032-4
DO - 10.1016/1010-6030(93)85032-4
M3 - Article
AN - SCOPUS:0001117984
SN - 1010-6030
VL - 70
SP - 125
EP - 133
JO - Journal of Photochemistry and Photobiology A: Chemistry
JF - Journal of Photochemistry and Photobiology A: Chemistry
IS - 2
ER -