UV-visible absorption data

A. Synthesis, Structure and UV-Visible Absorption Data of Oligosiloles... 

UV-Visible Absorption Data for Some Quinones Relevant to Lignin (sh = shoulder)... 

Table 13.10. UV-visible Absorption Data for Compounds 135-140 in CH2CI2...

Table 111,2 UV-Visible absorption data for common natural product carotenoids ...

The UV-visible absorption data in CHCI3 of the silole-thiophene mixed systems show much longer absorptions in the visible region compared with thiophene homooligomCTs and homopolymers. Furthermore, significant bathochromic shifts accompany higher sUole ratios. The results have been ascribed to the lowering of the LUMO level in the r-systons accompanied by an increase in the silole content, as demonstrated by ab initio calculation studies ... 

Both molecular and transition dipole moment orientation can be probed within the solid state samples, especially upon combining structural information with polarized absorption measurements. Small-area electron diffraction experiments are also effective since they allow the orientation of crystalline regions within polymer nanofibers to be probed. Most of these techniques are already well established from the study of polymer alignment in thin-films. Improved analysis methods, which make use of combined polarized Raman spectroscopy and UV-visible absorption data, are especially worthwhile to be mentioned as valuable tools to investigate the orientational properties of light-emitting polymer systems. We will come back in depth to optical properties of polymer nanofibers in Chapter 5. 

Derive information relevant to mechanistic studies of singlet states (from UV-visible absorption spectra and from fluorescence data) and triplet states (from phosphorescence data). 

Steady-state UV-visible absorption spectrum of the NKX-2311/ZnO film is also shown in Fig. 1. It was found that adsorption of the dye onto ZnO and TiC>2 (data not shown) leads to the spectral blue-shift of the dye absorption by 15 and 25 nm, respectively, and slight broadening compared with the spectrum in solution. When a bare ZnO film (without dye) was excited at 355 nm with the nanosecond laser, an absorption band shown by the dashed line in the same figure was observed in the near IR region. This band is assigned to intra-band transitions of electrons in the conduction band [10], Electrons in Ti02 showed weaker absorption in the near IR region. 

Spectroelectrochemical cells that permit redox titrations of precious biological samples, require exclusion of oxygen, and allow acquisition of data from multiple spectroscopic domains have been described. A recent example of these cell designs combines electron paramagnetic resonance spectroscopy with UV-visible absorption spectroscopy [71] for studies of flavoproteins. 

Data from the UV spectra of pyridothiadiazines (48a-e) suggest that in water the preferred tautomer is the N(8)—H form, as has been observed for related heterocyclic systems <91SC827>. The UV-visible absorption spectra of pyrido[2,3-c][l,2,6]thiadiazines (49) and (50) were determined as part of a study into their use as laser dyes <93MI 717-07). 

If an unstable species is generated continuously in a flow system, its decay establishes steady-state concentrations that decrease with distance downstream from the point of generation. It is thus possible to detect spectroscopically the unstable intermediate, though, of course, the spectra will necessarily be complicated by the presence of unreacted reagents or carrier material. Flow methods may be used to look at unstable species in the gas phase or in solution. They are ideally suited to kinetic measurements since, if the velocity of the flow of gas or liquid is known, it is possible to measure the rate of decay of the species under investigation. Early experiments used UV-visible absorption or emission to monitor the species in the flow however, such methods give only limited structural data. A more modem innovation is the use of tunable IR lasers to obtain high-resolution vibrational spectra. 

The method of moments analysis has since been used extensively to derive the magnetic moments of the ground and/or excited states from MCD spectral data by determining the intensity of the MCD and UV-visible absorption bands. In instances where the bands overlap extensively, spectral band deconvolution techniques have also been used. 

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