Transition, non-radiative

Figure Bl.1.3. State energy diagram for a typical organic molecule. Solid arrows show radiative transitions A absorption, F fluorescence, P phosphorescence. Dotted arrows non-radiative transitions.

Radiative and non-radiative transitions of rare-earth ions in glasses. R. Reisfeld, Struct. Bonding (Berlin), 1975, 22,123-175 (56). 

Reisfeld R (1975) Radiative and Non-Radiative Transitions of Rare Earth Ions in Glasses. 22 123-175... 

The polydiacetylene crystals (1-4) most strikingly corroborate these conjectures. Along this line of thought is also shown that this electron-phonon interaction is intimately interwoven with the polymerisation process in these materials and plays a profound role there. We make the conjecture that this occurs through the motion of an unpaired electron in a non-bonding p-orbital dressed with a bending mode and guided by a classical intermolecular mode. Such a polaron type diffusion combined with the theory of non radiative transitions explains the essentials of the spectral characteristics of the materials as well as their polymerisation dynamics. ... 

Here we outline a dynamical description (42) of the polymerisation of the polydiacetylenes. The approach relies much on the one used (43,44) in the theory of non radiative transitions in crystals and the soliton description of the defects in the lD-or-ganic semiconductors. 

Radiative and non-radiative transitions between electronic states... 

Internal conversion is a non-radiative transition between two electronic states of the same spin multiplicity. In solution, this process is followed by a vibrational relaxation towards the lowest vibrational level of the final electronic state. The excess vibrational energy can be indeed transferred to the solvent during collisions of the excited molecule with the surrounding solvent molecules. 

Radiative and non-radiative transitions between electronic states 39 Box 3.2 Spontaneous and stimulated emissions... 

Finally, I refer back to the beginning of this paper, where the assumption of near-adiabaticity for electron transfers between ions of normal size in solution was mentioned. Almost all theoretical approaches which discuss the electron-phonon coupling in detail are, in fact, non-adiabatic, in which the perturbation Golden Rule approach to non-radiative transition is involved. What major differences will we expect from detailed calculations based on a truly adiabatic model—i.e., one in which only one potential surface is considered [Such an approach is, for example, essential for inner-sphere processes.] In work in my laboratory we have, as I have mentioned above,... 

FIGURE 7.5 A Jablonski diagram. The solid horizontal lines represent molecular orbitals, with singlet states on the left and triplet states on the right. The arrows represent transitions between these levels, with straight lines for radiative transitions and wavy lines for non-radiative transitions. For the radiative transitions, absorption corresponds to the upward arrows at left, fluorescence corresponds to the downward arrows, and phosphorescence is represented by the diagonal arrow from Tj to Sq. 

Furthermore the dipole transition 2p-ls ean oeeur. The ealculated value for the prohahility of this transition is / i=7.910 s. This value is signifieantly higher than the eorresponding non-relativistie value [3], It is important to note that the value P3 is larger than the probability of the radiation transition pm-psn and that of the non-radiative transition pia - fm. The next transition p a fm oeeurs without radiation during the time 10 s, with ejeetion of the muon. 

Transitions between trapping states for electrons above and for holes below E are non-radiative transitions and involve the emission or absorption of phonons only. 

Fig. 1. Generalized energy level scheme of an organic dye molecule. Straight arrows radiative transitions, wavy arrows non-radiative transitions. The sigmas, kays, and taus are the corresponding cross-sections, transition rates, and lifetimes, respectively...

It is quite interesting to note that the neodymium-decay time is 25 per cent larger in the coactivated glass than in the single activated glass. This could be due to changes in either radiative or non-radiative-transition probabilities. The authors do not give an explanation as to the nature of the increase. 

After absorption, the energy can relax by emission of photons (Fig. 11.3) or by non-radiative transitions. The most frequent radiative transitions include phosphorescence and fluorescence. These are the basis of other methods of analysis that will be discussed in Chapter 12. 

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