Emission energies, table

Table 7.1. Ka and K/3 line emission energy for the elements used in our multilayer target...

Luminescence is, in some ways, the inverse process to absorption. We have seen in the previous section how a simple two-level atomic system shifts to the excited state after photons of appropriate frequency are absorbed. This atomic system can return to the ground state by spontaneous emission of photons. This de-excitation process is called luminescence. However, the absorption of light is only one of the multiple mechanisms by which a system can be excited. In a general sense, luminescence is the emission of light from a system that is excited by some form of energy. Table 1.2 lists the most important types of luminescence according to the excitation mechanism. 

Table 14.5 Measured and predicted absorption and emission energies (eV) for 8-hydioxyquinoline and Alq3...

Table 1 Calculated values for the ground (GS) and excited (EXC) state HOMO-LUMO energy gaps and for the absorption and emission energies calculated within the A-SCF approach for the considered H-Si-NC. All values are in eV...

A number of papers present in literature consider the HOMO-LUMO gaps of the ground and excited state as the proper absorption and emission energies this leads to the wrong results, mostly for smaller clusters. In fact, from Table 1 it is clearly seen that the smaller the H-Si-NC, the greater is the difference between the absorption and HOMO-LUMO ground-state... 

Fig. 8 Correlation between redox and emission energies, Eq. 3, for the series of Table 6. Empty points are for the 3LC emitters (tpy)2lr(PPh2CH2)2BPh2 and (tpy)2lr(dppe) (CF3SO3) [36]...

Table 2.1 Absorption and emission energies (eV) calculated at TDB3LYP/6-31+G(d,p) level in cyclohexane, acetonitrile and water...

Additional support for the orbital nature of the emissive state in the Pt(diimine)(dithiolate) complexes is obtained from the electrochemical data given in Table III. The formation of the emissive state formally involves oxidation of the HOMO having dithiolate and metal character and reduction of the LUMO, which is diimine localized. There should therefore exist a correlation between the energy of the excited state and the difference between the oxidation and reduction potentials for each complex. Indeed, such a linear correlation was found for the emission energies of the complexes a similar correlation was obtained when absorption energies for the solvatochromic transition were plotted (108). 

In addition to their effects on emission energy, the diimines and dithiolates also influence the emission lifetime and quantum yield of the Pt(diimine) (dithiolate) chromophore. The complexes display lifetimes ranging from 1 ns to > 1 ps and <3>eill ranging from < 10 5 up to 6.4 x 10-3, indicating such an influence on the kinetics of excited-state decay (see Table II). The tdt complexes have lifetimes that are significantly longer than those measured previously for... 

Based on the above analysis validating Fig. 4 for estimating excited-state redox potentials, values of YPt / ) and (Pt+/ t ) were estimated for both series of Pt(diimine)(dithiolate) complexes studied by Cummings and Eisenberg (109) using electrochemical data and emission energy maxima at 77 K to estimate The results are summarized in Table III. It was found that ligand variation... 

In Luc environment, we obtained two representative structures, models A-a and A-b. These two gave the emission energies of 2.33 and 2.08 eV, respectively, as shown in Calc. Ill in Table 4-5. Since these values were close to the experiment (2.23 eV) [128, 129], keto-OxyLH2 in the anionic form (keto-s-trans(-l) in Figure 4-12 (a)) was confirmed to be the yellow-green emitter in Luc environment. The character of the excited state is one-electron transition from HOMO(tt) to LUMO(tt ), and these orbitals are clearly localized within OxyLH2. 

---