Singlet molecular oxygen lifetime

J. G. Parker and W. D. Stanbro, Optical determination of the collisional lifetime of singlet molecular oxygen in acetone and deuterated acetone, J. Am. Chem. Soc. 104, 2067-2069 (1982). 

Arnold et al.24 have calculated radiative lifetimes for the various collision complexes of singlet molecular oxygen on the basis of a collision time of 10"13 sec. The data for wavelengths and transition probabilities are presented in Table III. A recent paper25 describes the theory of double electronic transitions, and gives calculated oscillator strengths for the oxygen systems. 

Rossbroich, G., Garcia, N.A., and Braslavsky, S.E. (1985) Lifetime of singlet molecular oxygen determined by time-resolved thermal lensing, in Bensasson, R.V., Jori, G., Land, E.J., and Truscott, T.G. (Eds.), Primary Photoprocesses in Biology and Medicine, New York, Plenum Press, pp. 197-199. 

Typical singlet lifetimes are measured in nanoseconds while triplet lifetimes of organic molecules in rigid solutions are usually measured in milliseconds or even seconds. In liquid media where drfifiision is rapid the triplet states are usually quenched, often by tire nearly iibiqitoiis molecular oxygen. Because of that, phosphorescence is seldom observed in liquid solutions. In the spectroscopy of molecules the tenn fluorescence is now usually used to refer to emission from an excited singlet state and phosphorescence to emission from a triplet state, regardless of the actual lifetimes. 

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