TP excitation/spectra

Figure 3.8. Comparison of OP and TP excitation spectra for the dipolar compound 1 solvent is toluene. (Adapted from Ref. [224].)...

Normalized TP excitation spectra of 22a-c are plotted in Figure 3.28. Data taken between 710 and 890 nm show the highest excitation energy for 22a, while 22b and 22c exhibit two absorption bands at higher wavelengths. All three spec-... 

Figure 3.30. Experimental TP excitation spectra of the chromophores 35-37. (From Ref. [296] with permission of Elsevier.)...

Comparison of OP and TP excitation spectra is shown for 38 in Figure 3.34. For this class of oligomers, the TP excited state displays a higher excitation energy in comparison to the lowest OP excited state. The results for 38-40 were essentially the same. Thus, the energetic relations depicted in Figure 3.33 are justified. This has a strong impact on the photochemistry, particularly for 40. Either OP or TP excitation results in the same photochemically active state, Si, and therefore the same photochemical pathways. 

This was concluded by comparison of the TP excitation spectra of the reference compounds 58b and 58c with the paracyclophane containing substances 78a-b (Table 3.7). These chromophores exhibit significant increase of 5 in the case of 78 with increasing length (n) compared to the ID reference compounds (Fig. 3.45). The paracyclophane compounds exhibit an approximately... 

The TPA cross sections of the D-A-D distyrylbenzenes (Table 3.9) 100-103 exhibit a higher 8 in comparison with 58. TP excitation spectra of 99, 100, 102, and 103a are shown in Figure 3.49. Incorporation of electron-withdrawing... 

Figure 3.57. TP excitation spectra of 141 in acetonitrile in the absence (upper curve) and in the presence of calcium ions (middle curve) and lithium ions (lower curve) [544],...

Furthermore, normalization of the excitation energy yields the spectra of 1 shown in Figure 3.8. This picture shows that both OP and TP excitations result in spectra exhibiting maxima at approximately the same position. Similar relations were found for 2 and 3 as well. Energy differences between OP and TP... 

Figure 3.24. (a) Photoluminescence intensity versus pump power for an excitation energy of 1.61 eV. The line represents a linear fit with a slope of 1.97. (b) Spectra of OP photoluminescence (—) recorded at an excitation energy of 3.1 eY and TP excited photoluminescence (—) measured at an excitation energy of 1.61 eY. (From Ref. [174] with permission of Wiley-VCH.)... 

Figure 3.28. Normalized TP fluorescence excitation spectra for 22a, 22b, and 22c. (From Ref. [384] with permission of the American Chemical Society.)...

The small hypsochromic shift of TP excitation maximum for 74 compared to 58b reflects the influence of the re-system on TP excitation energy. In contrast, both anthracene bearing chromophores 75b and 75c exhibit significantly smaller 8 compared to 74. This is caused by the smaller electronic coupling between the one-photon (OP) state and the two-photon (TP) excited state (Table 3.7). TPA and OPA spectra for 74 and 75b-c are shown in Figure 3.42. 

Figure 3.45. Experimental and theoretical TP induced fluorescence excitation spectra (without (e) from the original Ref. [474]) for (a) compound 58b, (b) compound 78a, (c) compound 58c, (d) compound 78b, and (f) compound 78c. Experimental results (a) femtosecond measurements using fluorescein as standard ( ) nanosecond measurements using fluorescein as standard (o) nanosecond measurements using bis(methylstyryl)ben-zene as standard. Theoretical results solid line. (From Ref. [474] with permission of the American Chemical Society.)...

The slope of the logarithmic plot of absorbance change versus the logarithm of the pump intensity is 1.84, indicating the occurrence of a nonlinear absorption process. The TPA cross section of isomer A is about 0.76 GM and an increased 8 was observed for isomer B (8 = 6 GM) due to the closed ring form and higher planarity. One-photon and two-photon induced isomerization of 143 shown in Eq. (62) results in similar spectra and in the same isosbestic points observed at 329 nm, 377 nm, and 429 nm. These results clearly indicate participation of the same excited state applying either OP or TP excitation. Quantum yields are close to unity. 

Thus far, the experimental investigations of TP spectra of M2ALnX6 have utilized the more sensitive technique of excitation spectra rather than ab-... 

Fig. 8.11 Evidence of a pairing gap in a strongly interacting Fermi gas radio-frequency excitation spectra of a pairing nltracold two-component gas of Li at various temperatures T (Tp = 2.5 pK). The vertical dotted line marks the atomic transition, and the arrows indicate the effective pairing gap Av. (Reprinted with courtesy and permission of AAAS (USA) from Chin et al. 2004.)...

Figure 11.28 (a and b) UV-vis absorption spectra of ligand TP and PM. (c) Photoluminescence spectra include excitation and (d) emission of the complex Dy(PM)3 (TP)2 [75]. (Reprinted with permission from Z.F. Li et al., Synthesis, structure, photoluminescence, and electroluminescence properties of a new dysprosium complex, The Journal of Physical Chemistry C, 111, 2295-2300, 2007. 2007 American Chemical Society.)... 

Figure 3.34. Absorption spectra obtained for TP (left axis) and OP (right axis) excitation of 38 in toluene at room temperature. (Adapted from Ref. [392].)...

Fig. 3. Comparison of LIF spectra for FIFIC, BSA, Yeast, BT, NADH and TP for excitation with 266nm (a, c) and 355nm (b,d). BSA and Yeast were measured in two concentrations marked by Ic and he for details see Tab. 1.

---