Optical absorption band

In order to explain the changing optical properties of AIROFs several models were proposed. The UPS investigations of the valence band of the emersed film support band theory models by Gottesfeld [94] and by Mozota and Conway [79, 88]. The assumption of nonstoichiometry and electron hopping in the model proposed by Burke et al. [87] is not necessary. Recent electroreflectance measurements on anodic iridium oxide films performed by Gutierrez et al. [95] showed a shift of optical absorption bands to lower photon energies with increasing anodic electrode potentials, which is probably due to a shift of the Fermi level with respect to the t2g band [67]. 

Valence Band Spectroscopy. Optical and electronic properties of UPD metal flms on metal electrodes have been studied in situ by means of differential- and electroreflectance spectroscopy [98], Optical absorption bands, however, reflect a combined density of electronic states at a photon energy which is the energetic difference of... 

Significantly, the bio-inorganic and polymer-containing PM nanocomposites showed no significant shift in the protein amide I and II vibration bands, or in the characteristic 567 nm optical absorption band of the retinal chromophore of BR, indicating that the structural and dynamical properties of the membrane-bound... 

Type 1 Cu(II) intense (e > 3000 M 1 cm ) blue (2max 600 nm) optical absorption band EPR spectrum with an uncommonly small hyperfine splitting in gn region. 

Table 4. Cis effects in porphyrins Rh(OEP)LX ([22] -> 12 ). Optical absorption bands (X) and porphyrin proton magnetic resonances (S) at Ca (solvents CHC13 or CDC13 ...

Table 17. Metal effects in the physicochemical data of some group Villa metalloporphyrins (wavelengths of the optical absorption bands, = a for OEP, kp for TTP or TPP redox...

A certain transition metal ion presents two optical absorption bands in a host crystal whose zero-phonon lines are at 600 nm and 700 nm, respectively. The former band has a Huang-Rhys parameter 5 = 4, while for the latter 5 = 0. Assuming coupling with a phonon of 300 cm for the two bands (a) display the 0 K absorption spectrum (absorption versus wavelength) for such a transition metal ion (b) display the emission spectra that you expect to obtain nnder excitation in both absorption bands and (c) explain how you expect these two bands to be affected by a temperature increase. 

Chrom means colour and electro implies an electrochemical process, so electrochromic means colour change or generation of a new optical absorption band caused by an electron-transfer reaction. 

Kundt rule spect The rule that the optical absorption bands of a solution are displaced toward the red when its refractive Index Increases because of changes in composition or other causes. kOnt, rtil ) kurchatovium chem The name suggested by workers in the Soviet Union for element 104. Symbolized Ku.. kar cha to ve am )... 

The solute benzene radical cation was formed on pulse radiolysis of an acidic aqueous solution of benzene. The transient optical absorption bands (A-max = 310, 350-500 nm) were assigned to the solute benzene radical cation which is formed on acid-catalysed dehydration of the OH adduct. The radical cation is able to undergo an electron-transfer reaction with Br and was found to be a strong electron oxidant. Pulse radiolysis has been used to study the complex reaction that follows electron addition to hydroxybenzophenones (HOBPs). The various radical species involved have been characterized spectrally and their p/fa values evaluated. The differences... 

The appearance of the optical absorption bands (Q and B) has a clear threshold at a low non-zero coverage, implying that the electronic structure of the first adsorbed molecules is different from that of the bulk ones. Thus, a clear distinction between molecules directly bonded to the aluminium substrate d- < 0.3 run) and molecules not directly bonded to the substrate d- >0.3 nm) can be made. In the latter case the electronic structure, as revealed by EELS, is identical to that of bulk CuPc, while in the former case modification of the electronic structure prevents transitions toward the LUMO orbital. Above 1.0 nm the Q and B band intensities saturate. The optical transitions are inhibited for molecules directly bonded to the alumiiuum substrate... 

The are two other important advantages of the X-ray excitation technique (a) Levels lying within the optical absorption band of the host may be excited and (b) filters are not required to eliminate leakage of the pumping radiation from the detector. 

One the other hand, short-lived intermediates formed from styrene by radiations were studied by the pulse radiolysis technique by Metz et al. (43). They observed the anion radicals of styrene as an optical absorption band with the maximum at 370 mp, but could not find cationic intermediates. Shida and Hillma irradiated the 2-methyltetrahydrofuran glass and butylchloride glass, both containing styrene, and observed the absorption bands due to added styrene at 410 mp and 350 mp, respectively. The former band was assumed to be due to the anion-radicals and the latter to the cation radicals (44). 

Hart and Boag s discovery (13) of the broad optical absorption band of the e aq in irradiated water confirmed the conclusion (7, 8) that the eaqy instead of the H atom, is the principal reducing intermediate in the bulk of the solution. Understandably, the Lea-Platzman (31) viewpoint of the primary physical processes of energy absorption gained currency over the Samuel-Magee (34) viewpoint. Their disagreement concerned the fate of the electron from primary ionization of water Platzman (31)... 

Figure 5.11 in oxidative solutions of Cc4(S04)3 or reducing solutions of H2NNH2 produced a cycle of complete disappearance/restoration of the MLCT optical absorption band, thereby establishing that the SAM could be used as a reversible molecular switch. 

Fig. 12. Infrared optical absorption bands observed in ethylenediamine solutions (A) spread in band shape of er observed by pulse radiolysis, (B) spread in band shape observed in alkali metal solutions. [Adapted with permission from W. A. Seddon and J. W. Fletcher, Journal of Physical Chemistry, 84, 1104 (1980). Copyright 1980 American Chemical Society.]...

The observation (153) of a single transient optical-absorption band... 

The SCs at the silica surface readily react with molecular oxygen. This reaction is convenient to monitor optically (Figure 7.23a). Oxygen chemisorption is accompanied by the disappearance of the optical absorption band of SCs. The adsorption of one molecule leads to the decay of one SC. Quantum-chemical calculations show that the three-member cyclic symmetric structure (Figure 7.24) is the most stable product of oxygen addition to the SC [74] ... 

Fig. 7.25. The optical properties of DOSG. (a) The optical absorption bands (b) the electronic nature of the excited states responsible for the absorption bands of the center near 3 and 5 eV (see text for detail).

These experimental data indicate that the optical absorption band of SG is inhomogeneously broadened due to the sites that differ in both spectral parameters and reactivity. 

---