Perrin-Jablonski diagram

Just as above, we can derive expressions for any fluorescence lifetime for any number of pathways. In this chapter we limit our discussion to cases where the excited molecules have relaxed to their lowest excited-state vibrational level by internal conversion (ic) before pursuing any other de-excitation pathway (see the Perrin-Jablonski diagram in Fig. 1.4). This means we do not consider coherent effects whereby the molecule decays, or transfers energy, from a higher excited state, or from a non-Boltzmann distribution of vibrational levels, before coming to steady-state equilibrium in its ground electronic state (see Section 1.2.2). Internal conversion only takes a few picoseconds, or less [82-84, 106]. In the case of incoherent decay, the method of excitation does not play a role in the decay by any of the pathways from the excited state the excitation scheme is only peculiar to the method we choose to measure the fluorescence (Sections 1.7-1.11). 

The Perrin-Jablonski diagram (Figure 3.1) is convenient for visualizing in a simple way the possible processes photon absorption, internal conversion, fluorescence, intersystem crossing, phosphorescence, delayed fluorescence and triplet-triplet transitions. The singlet electronic states are denoted S0 (fundamental electronic state), Si, S2,... and the triplet states, Ti,T2,. Vibrational levels are associated with each electronic state. It is important to note that absorption is very fast ( 10 15 s) with respect to all other processes (so that there is no concomitant... 

Fig. 3.1. Perrin-Jablonski diagram and illustration of the relative positions of absorption, fluorescence and phosphorescence spectra.

Nickel B. (1997) From the Perrin Diagram to the Jablonski Diagram. 

Presentations of Jablohski s contribution to spectroscopy in the frame of the evolution of science and political situation in the 1930s and 1940s have been published [14, 15]. The contribution of Jacques and Francis Perrin, Jablonski, Vavilov, Levshin, Lewis, and Kasha to the definition of state diagram has been critically evaluated and the originality of each one commented by Nickel [16, 17]. The topic was discussed at the first congress on photoluminescence in Warsaw, May 20-25, 1936 (Pringsheim president, Jablonski secretary). The lively discussion that took place on that occasion has been retraced in detail by Nickel [18]. 

Nickel B (1996) From the Perrin diagram to the Jablonski diagram. EPA Newslett 58 9-38... 

---