Transient absorption measurements spectrum generation

A laser pulse can be used instead of the van der Graff generator to produce the electron-hole pair, which is a technique known as flash photolysis, time-resolved, microwave conductivity or FP-TRMC. The main disadvantage is that the concentration of electron-hole pairs formed in this way is more difficult to estimate. Usually, it can only be used to measure the product of the quantum yield and the sum of the mobilities (oriented films [15,16]. More recently a variation on this method has been introduced in which the transient absorption spectrum is measured simultaneously. This provides structural information on the charge carriers and (provided assumptions are made) allows their concentration to be determined yielding Sp, [17,18]. 

Fig. 4. a) a) Static /.m-edge x- ray absorption spectrum of ground state [Rul (bpy)3]2+ (trace R), and excited state absorption spectrum (trace P) generated from the transient data curve T in (b) via eq. 2. b) Transient x-ray absorption spectrum (T) of photoexcited aqueous [Ru"(bpy)3]2+ measured 50 ps after laser excitation. 

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