Interaction chromophore

Unlike PMDs having a single chromophore, the absorption band of a bis-dye spHts into two components, so that one maximum is shifted bathochromicaHy and the other hypsochromicaHy with respect to the absorption maximum of the parent dye. The distance between bis-dye maxima depends on the magnitude of the chromophore interaction. Interaction of this kind has been discovered to be universal (45,46). 

Dye Aggregation. Another important kind of chromophore interaction is the dye aggregation. A number of reviews exist that treat the stmcture and appHcation of polymethine dye aggregates (3,48—51) (see also Cyaninedyes). 

Barium and strontium salts of polystyrene with two active end-groups per chain were prepared by Francois et al.82). Direct electron transfer from tiny metal particles deposited on a filter through which a THF solution of the monomer was percolated yields the required polymers 82). The A.max of the resulting solution depends on the DPn of the formed oligomers, being identical with that of the salt of polymers with one active end-group per chain for DPn > 10, but is red-shifted at lower DPn. Moreover, for low DPn, (<5), the absorption peak splits due to chromophor-chromophor interaction caused by the vicinity of the reactive benzyl type anions. 

The Langmuir-Blodgett deposition is one of the best methods to prepare highly organized molecular systems, in which various molecular parameters such as distance, orientation, extent of chromophore interaction, or redox potential can be controlled in each monolayer. We have been studying... 

We see a colour because a chromophore interacts with light. 

Chromoionophores, 20 517-518 Chromonema fibers, 17 612 Chromonic liquid crystals, 15 101 Chromophore interaction, in dye molecules, 20 511-512... 

H2O, where N/2 molecules have N OH stretch chromophores. In this case we need to label the transition dipoles and frequencies by an index i that runs from 1 to N. In addition, in general these chromophores interact, with couplings (in frequency units) coy. In this case the above mixed quantum/classical formula can be generalized to [95 98]... 

The general strategy for establishing the sites of protein-chromophore interactions in rhodopsin involves introduction of selective 13 C labels at each position along the length of the retinal chromophore. 

The function of the bulky butyl groups on the thiophene ring of the chromophore is the prevention of unwanted chromophore-chromophore interactions. This and other design principles have led to the development of new materials, such as (5.12) and related chromophores, which when embedded in a polymer matrix give materials with dramatically improved performance. ... 

Here we present additional data in order to extract a characteristic control frequency and establish a detailed picture of the laser-chromophore interaction and the ensuing dynamics. This work demonstrates the use of coherent control as a valuable tool for the spectroscopy of complex molecules. 

In order to examine further the effect of the PNS and PNS-chromophore interactions upon the ultrafast twisting reactions of the PYP chromophore, we are examining also the effect of the PNS environment on the fluorescence dynamics of the PYP analogues where the PYP chromophore is replaced with similar but a little different chromophores. Among those PYP analogues, we show here results of the fluorescence dynamics studies of those with (a) locked chromophore and (b) ferulic acid chromophore. 

Fig. 4. Fluorescence dynamics studies on PYP analogues effects of the PNS - chromophore interactions.

R are used to control the Amax of the chromophore. Interaction of the dye releaser with ETAox yields the corresponding quinoneimine (84) which is hydrolyzed in alkali to give the sulfamoyl-solubilized yellow image dye (85). Derivatives of l-phenyl-3-pyrazolidinone (see Section 1.14.2.1.4) can function as electron transfer agents. 

Pure and doped crystals allow investigation of chromophore interactions and exciton motion. Polarized spectroscopy can be uniquely useful for assigning spectral features and determining orientations of intermediates or products in single crystals, but birefringence often makes the technique less versatile than might have been imagined (Section II.D.4). 

It was found that the quantum efficiency of the anodic photocurrent in the Chi a-DPL system was increased from 3-4% in the pure Chi a monolayer up to about 25% (65) in highly diluted mixed monolayers. This increase in efficiency was accompanied by red shifts of the photocurrent peak positions in the red and blue bands (e.g., in the red, from 675 nm (pure Chi a) to 665-670 nm (Chi atDPL 1/49)) and probably reflects the change in chromophore-chromophore interaction between Chi a molecules. 

The LB deposition is one of the best methods to prepare highly organized molecular systems, in which various molecular parameters such as distance, orientation, extent of chromophore interaction, or redox potential can be controlled in each monolayer. We have been studying photophysical and photochemical properties of LB films in order to construct molecular electronic and photonic devices. The molecular orientation and interactions of redox chromophores are very important in controlling photoresponses at the molecular level. Absorption and fluorescence spectra give important information on them. We have studied photoresponses, specific interactions, and in-plane and out-of-plane orientation of various chromophores in LB films [3-11], In addition to the change of absorp-... 

Let us briefly examine the color of a red wine. The wine contains color sites, or chromophores. The photons that are not captured pass through and give us the red coloration. We see color because a chromophore interacts with light. 

In particular, V° describes a solute-solute Coulomb and exchange-correlation interaction corrected by an overlap contribution. The effects of the solvent on V° are implicitly included in the values of the transition properties of the two chromophores before the interaction between the two is switched on. These properties can in fact be significantly modified by the reaction field produced by the polarized solvent. In addition, the solvent explicitly enters into the definition of the coupling through the term VIEF of Equation (3.150), which describes the chromophore-solvent-chromophore interaction. 

Kaino and co-workers [255] have investigated the effect of polymer polydis-persity on electro-optic materials properties. No dependence on polydispersity was observed for guest host materials but for Disperse Red chromophores covalently attached to monodisperse polystyrene weaker absorption tails were observed. This result suggests that chromophore-chromophore interactions are modified by the polymer host. 

Octant contributions are in principle additive, except when the chromophores interact. In diketones where the two C=0 groups do not interact electronically, e.g., as in 1,2-diketones, it can be seen from a few representative diketones (Table V) that the CE of the diketone is usually the sum of the CEs of the component monoketones. However, at present there are too few examples to warrant a more comprehensive analysis. 

The environment here can be the temperature, solvent, chromophore interaction with another molecule, etc. 

The concentration-dependent effect of calf thymus DNA on the visible absorption spectrum of tilorone hydrochloride indicates that the tilorone chromophore interacts with DNA. Figure 2 depicts the visible absorption spectra of tilorone alone (curve one), or in the presence of yeast RNA (curve two), denatured DNA (curve three) and native double-stranded DNA (curve four). The visible spectra indicate that at equimolar concentrations, DNA in its double helical state produced largest changes... 

Twisted internal charge transfer TtCT) Intramolecular, photoinduced charge transfer between chromophores interconnected by a single bond leading to an excited state (a TICT state) in which the chromophores interact only weakly because of a considerable twist about the interconnecting bond. 

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