Absorption and emission energies

Fig. 7 Absorption and emission energies of fluorenone versus polarity parameter n. Solid marks denote the data for alcohols (courtesy of M. Jozefowicz)...

Figure 1.10 (a) The absorption and emission energies for a two-level system (rigid lattice), (b) The absorption and emission energies showing the Stokes shift (vibrating lattice). 

Because EH calculations show that these factors strongly effect the HOMO-LUMO gaps, different absorption and emission energies are expected to exist. (Adapted from Rawashdeh-Omary et al., 2001)... 

The difference in absorption and emission energies (=2 A for the present model) is the so-called Stokes shift. Also, note that A increases with... 

Figure 14.2 Schematic relationship between vertical absorption and emission energies and the adiabatic energy difference between the ground and excited states. [Note that a more rigorous treatment requires inclusion of ZPVE and thermal contiibutions in the adiabatic energy difference, and consideration of Franck-Condon overlap between quantized vibrational states for the vertical processes some of these points are discussed in Section 14.5.]...

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... 

Re(dmpe)32+. Of interest is that both complexes make available extremely oxidizing excited states using a visible photon, since their absorption and emission energies are 528 nm (600 nm) for Re, and 590 nm (681 nm) for Tc, respectively. Unrestricted open shell TDDFT calculations confirm the nature of the transitions as LMCT and predict the proper relative energies of Re versus Tc. 

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

Now that we have identified a preferential entrance position and direction, we can move to analyze the effects of the interface on absorption and emission energies. 

Figure 13 The CT adiabatic free energy surfaces in the CT inverted region Ae = 0.7, APIIX = -1.0, AEii/X = 3.0. The points Y and Y+ indicate the minima of the lower and upper adiabatic surfaces, respectively. The labels hv ],s/em are absorption and emission energies, and AEmin is the minimum energy gap between the free energy surfaces (Eq. [149]).

The singlet-triplet and ground-excited state energy differences and the absorption and emission energies are treated as unsigned quantities and taken as positive. 

From Fig. 1 it can be seen that as the number of repeat units increases both absorption and emission energies red shift but saturate at around 5-7 repeat units, also the Stokes shift decreases for longer oligomers. This is a result of the strong influence of ring rotations on the excited states and the degree to... 

Figure 3.10(b) shows that the absorption and emission energies are similar between H-SiQDs and HsC-SiQDs, while those of HS-SiQDs, H2N-SiQDs, and HQ-SiQDs are noticeably lower than those of H-SiQDs and H3C-SiQDs [26]. For instance, the absorption and emission energies of Si3sH36 are 4.37 and 2.89 eV respectively. Those two values slightly decrease to 4.18 and 2.84 eV in Si35(CH3)36. In... 

Fig. 3.10 (a) Schematic representation of the absorption and emission processes, (b) Calculated absorption and emission energies of SiQDs as a function of the electronegativity of the surface functionalization elements [26]. Reprinted with permission from (Li QS, Zhang RQ, Lee ST, Niehaus TA, Frauenheim T (2008) Optimal surface functionalization of silicon quantum dots, J Chem Phys 128 244714). Copyright (2008), American Institute of Physics... 

Thompson et al.465 reported syntheses and structures of [Ir(pz-Tp)(A,C2-(2-para-tolylpyridine))2] (=[Ir(pzTp)(tpy)2]) and [Ir(pz-Tp)(A,C2 -(4/,6/-difluorophenylpyridine))2] (=[Ir(pzTp)(dfppy)2]). The Ir-N-N-B-N-N cycle of [Ir(pzTp)(tpy)2] adopts a half-chair conformation, more flattened than the typical boat conformation. The poly(pyrazolyl)borate ancillary ligand affects the absorption and emission energies of these complexes by tuning the HOMO energies. The electron-withdrawing pzTp decreases the electron density on the iridium, stabilizing the metal-centered HOMOs.465... 

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