Water electronic absorption

Sometimes, the physicochemical properties of ionic species solubilized in the aqueous core of reversed micelles are different from those in bulk water. Changes in the electronic absorption spectra of ionic species (1 , Co ", Cu " ) entrapped in AOT-reversed micelles have been observed, attributed to changes in the amount of water available for solvation [2,92,134], In particular, it has been observed that at low water concentrations cobalt ions are solubihzed in the micellar core as a tetrahedral complex, whereas with increasing water concentration there is a gradual conversion to an octahedral complex [135],... 

Table 11 Electronic absorption spectra (in water) and electrochemical data (in CH3CN) for Ni11 complexes...

Apart from molecular vibrations, also rotational states bear a significant influence on the appearance of vibrational spectra. Similar to electronic transitions that are influenced by the vibrational states of the molecules (e.g. fluorescence, Figure 3-f), vibrational transitions involve the rotational state of a molecule. In the gas phase the rotational states may superimpose a rotational fine structure on the (mid-)IR bands, like the multitude of narrow water vapour absorption bands. In condensed phases, intermolecular interactions blur the rotational states, resulting in band broadening and band shifting effects rather than isolated bands. 

Tatarkiewicz et al. (1988) noticed that in their implantation conditions (1.65 MeV protons or 2 MeV deuterons with an ion current density of 0.3, A/cm2) in InP, the electronic absorption due to lattice defects was lower for the deuteron implantation than for the proton implantation. This means that, at least for the deuteron implantation, on-beam annealing occurred during the implantation even though the sample was water... 

The addition of water causes the formation of a coagulated phase of PBT solutions in any of the solvents named above (of course, the amount of water tolerated varies with the solvent, with the PPA solvent being the most tolerant toward water) (4). In very dilute solutions, the water causes enhanced depolarized scattering, interpreted to be the result of the formation of aggregates in which the rodlike chains are in parallel arrays (10). In more concentrated solutions, a gel phase is created (11,12). In either case, the electronic absorption spectra is altered from that characteristic of the protonated chain to that characteristic of the deprotonated, dry polymer (10). In the following we will report observations on this phase transition. 

The compounds have been characterized by elemental analyses, spectroscopy [electronic absorption, IR, Raman (or resonance Raman for the blue compounds with Ae = 1064 nm)], redox titration [for the determination of the (formal) number of Mo centers], thermal gravimetric analyses (TGA), and single-crystal X-ray structure analyses (see Refs. 2, 5 and literature cited therein). Mainly the crystals of the compounds that contain discrete wheel-shaped anions lose lattice water rapidly on removal from the mother liquor even at room temperature, a... 

Octaethylporphinato complexes of the type [M(OEP)(02CMe)2] (M = Zr or Hf) have been prepared by reaction of H2OEP and [M(acac)4] in molten phenol at 210-240 °C followed by crystallization from pyridine-acetic acid-water mixtures. The complexes have been characterized by IR and mass spectra703,704 and by electronic absorption and emission spectra.703 They have an eight-coordinate square antiprismatic structure (48) in which the four porphinato nitrogen atoms occupy the coordination sites on one square face and the two bidentate acetate... 

Ethylene glycol is a very viscous liquid and the molecule presents two close OH groups. It has to be noticed that, among all the different solvents studied by pulse radiolysis, the transition energy of the solvated electron absorption band is maximum in liquid ethylene glycol. For these reasons, the electron in EG seems to have a special behaviour and it is of great interest to study the dynamics of the formation of equilibrated solvated electron. Within this context, the present communication deals with the dynamics of solvation in EG of electrons produced by photoionisation of the solvent at 263 nm. The formation of solvated electrons is followed by pump-probe transient absorption spectroscopy in the visible spectral range from 425 to 725 nm and also in near IR. For the first time, the absorption spectrum of the precursor of the equilibrated electron is observed in EG. Our results are shortly compared by those obtained in water and methanol. 

It is worth noticing that, in contrast to what have been reported for the electron solvation dynamics in water and in alcohols at room temperature, we do not observe a hypsochromic translation of the electron absorption spectrum. 

Spectrophotometric assessment of chlorophyll content is based on the strong electronic absorption spectra of these pigments. Arnon (1949) developed an early method measuring 80% acetone/20% water plant extracts based on the electronic absorption spectra of chlorophylls a and b. Absorbance of the extract was measured at different wavelengths, and simultaneous equations were constructed based on extinction coefficients for each derivative s unique electronic absorption maxima. Over the... 

Cu Y. The absorption spectra of hydrated and dehydrated CuIJY zeolites are shown in Figs. 5 and 6, respectively. The dehydrated Cu Y zeolite also displayed a weak photoluminescence at 540 nm, in qualitative accord with the reports of partial autoreduction of Cu to Cu upon dehydration, which amounts to approximately 20% of Cu converted to Cu at the dehydration temperature of 400°C (3). The sharp peaks at 5200 and 7000 cm- in Fig. 5 are the (v+6) and (2v) vibrational bands of water (14). Their absence in Fig. 6 demonstrates that the dehydration of Cu Y is complete. Also, absence of the silanol (2v) band at 7300 cm- (I5) shows that hydroxyl groups are absent in the dehydrated Cu Y as well as in all subsequently treated copper zeolites. The broader bands between 9000 and 16000 cm and above 30000 cm- are electronic absorption spectra of the copper species in the hydrated and dehydrated Cu Y, as follows from their comparison with the spectra of NaY and CuxY. 

Fig. 32. The electronic absorption spectra of A) Co(CN)2(A2TDC) in water, B) Co(CN)2(Cbi) in water, C) Co(CN)2(A20DC) in methanol. Taken from Ref. [2] with permission...

Fig. 34. The electronic absorption spectra of cobalt complexes of octadehydrocorrin in water/meth-anol (99 1 v/v) at 3°C -— [Co(A2ODC)+, 6.38x 10"5M after disproportionation at [OH ]...

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