Measurement of the quantum yield of triplet formation and short triplet lifetimes by the transient grating technique

A transient grating method for measuring the quantum yield of triplet formation (Φisc) and lifetimes of short-lived triplet states is proposed. The method is based on a measurement of time dependence of a thermal grating signal with a nanosecond pulsed laser and a cw probe laser. The validity of the method is demonstrated by determining Φisc of a number of molecules whose Φisc are known. Advantages and limitations of this method are discussed in detail.