Red-shift of the excitonic level in two beam absorption spectra of GaSe

1988 ◽  
Vol 38 (4) ◽  
pp. 627-631 ◽  
Author(s):  
L Pavesi ◽  
V Capozzi ◽  
J L Staehli
Keyword(s):  
Absorption Spectra ◽  
Red Shift

Quinoline-annulated chlorins and chlorin-analogs

2016 ◽  
Vol 20 (01n04) ◽  
pp. 265-273 ◽  
Author(s):  
Joshua Akhigbe ◽  
Mengxi Yang ◽  
Michael Luciano ◽  
Christian Brückner
Keyword(s):  
Absorption Spectra ◽  
Functional Group ◽  
Bathochromic Shift ◽  
Red Shift ◽  
Simple Strategy

The OsO4-mediated dihydroxylation of quinoline-annulated porphyrin generates a quinoline-annulated dihydroxychlorin in a regioselective fashion. Its dihydroxypyrroline moiety, located at the opposite of the annulated pyrrole, is susceptible to the same functional group interconversions we previously demonstrated for non-annulated dihydroxychlorins: oxidations to the corresponding dione, lactone, and dialkoxymorpholine derivatives. The quinoline-annulated chlorin and derivatives are all characterized by absorption spectra that are much broadened and between 130 and 220 nm red-shifted compared to their non-annulated analogs. Absorbance maxima in the NIR up to well above 800 nm were recorded. We attribute the bathochromic shift to their extended [Formula: see text]-systems and inferred non-planarity, highlighting that quinoline-annulation is a particularly effective and simple strategy to red-shift the absorption spectra of chlorins and chlorin analogs.

Halogen-Substitution Effect on the Optical Absorption Bands of Uracil*

1974 ◽  
Vol 29 (9-10) ◽  
pp. 493-495 ◽  
Author(s):  
Wolfgang Lohmann
Keyword(s):  
Optical Absorption ◽  
Linear Function ◽  
Absorption Spectra ◽  
Electron Affinity ◽  
Substitution Effect ◽  
Ultraviolet Absorption ◽  
Red Shift ◽  
Electron Affinities ◽  
Absorption Bands ◽  
Extinction Coefficients

Abstract The ultraviolet absorption spectra of uracil and its 5-halogenated derivatives have been in ­ vestigated in regard to the electron attracting properties of the substituents. It could be shown that the position of the two absorption bands is proportional to the inverse of the electronegativity; the extinction coefficients are a linear function of the electron affinities. In this way, the red shift obtained upon substitution with halogens can be explained. Also, the decrease in absorbance of the absorption bands at λ > 250 nm, occuring concomitant­ ly, is understandable. The increase in absorbance with increasing electron affinity, as observed in the case of the absorption bands at λ < 250 nm, might question the assumption that this band is due to a higher pi -pi* excitation

Enhanced Photocatalytic Performance of Iodine Doped Bi2WO6 Nanostructures under Visible-Light Irradiation

2013 ◽  
Vol 423-426 ◽  
pp. 163-166 ◽  
Author(s):  
Bao Wei Cao ◽  
Yun Hua Xu
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Hydrothermal Method ◽  
Absorption Spectra ◽  
Visible Light Irradiation ◽  
Rhodamine B ◽  
Photocatalytic Performance ◽  
Red Shift ◽  
Light Irradiation ◽  
Photocatalytic Activities

Bi2WO6 doped with iodine ions were synthesized using hydrothermal method and their photocatalytic activities to degrade Rhodamine B (RhB) under visible-light was investigated. The successful incorporation of I ions in Bi2WO6 was proved by XRD and XPS. UV-vis absorption spectra results show that I ion was successfully doped into Bi2WO6 and a red shift for I-doped Bi2WO6 appeared when compared to pure Bi2WO6. The photocatalytic activities of the photocatalysts were evaluated by the decolorization of RhB under visible-light irradiation. The results showed that the photocatalytic activity of I-doped Bi2WO6 was much higher than the undoped Bi2WO6.

scholarly journals Red shift of absorption spectra of metal-doped TiO2 coatings

2018 ◽  
Vol 1115 ◽  
pp. 032055
Author(s):  
M V Shandrikov ◽  
A S Bugaev ◽  
A V Vizir ◽  
K P Savkin ◽  
E M Oks
Keyword(s):  
Absorption Spectra ◽  
Red Shift ◽  
Doped Tio2 ◽  
Tio2 Coatings ◽  
Metal Doped

Studies on Sonogashira Coupling Reaction of Dibenzoporphyrin

2012 ◽  
Vol 581-582 ◽  
pp. 317-321
Author(s):  
Jia Ying Yan ◽  
Ya Qing Feng ◽  
Fang Qun Zhou ◽  
Yi Wen Chang ◽  
Bao Zhang
Keyword(s):  
Absorption Spectra ◽  
Aromatic Ring ◽  
Coupling Reaction ◽  
Soret Band ◽  
Red Shift ◽  
Sonogashira Coupling ◽  
Sonogashira Coupling Reaction

Changing the proportion of NBS and porphyrin, dibromination of β, β’- π-extended porphyrins was found to selectively occur to the β and β’ position of the porphyrins which is antipotal to the fused aromatic ring. Subsequent Sonogashira coupling of the resultant dibromoporphyrin introduced a carboxylphenylethynyl group to the π-extended porphyrin and the π conjugation was thus further elongated. The coupling products have shown a broadening and a red-shift of the Soret band and Q bands in the UV-Vis absorption spectra compared with the π-extended porphyrin starting materials and the original unmodified porphyrins.

scholarly journals Influence of TiO2Nanocrystals Fabricating Dye-Sensitized Solar Cell on the Absorption Spectra of N719 Sensitizer

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Puhong Wen ◽  
Yinfeng Han ◽  
Weixing Zhao
Keyword(s):  
Solar Cell ◽  
Absorption Spectra ◽  
Red Shift ◽  
Dye Sensitized Solar Cell ◽  
Utilization Rate ◽  
Visible Absorption ◽  
Dye Sensitized ◽  
Ligand Charge Transfer ◽  
Charge Transfer Transitions ◽  
Mlct Band

The absorption spectra of N719 sensitizer anchored on the films prepared by TiO2nanocrystals with different morphology and size were investigated for improving the performance of dye-sensitized solar cell (DSC). We find that the morphology and size of TiO2nanocrystals can affect the UV-vis and FT-IR spectra of the sensitizer anchored on their surfaces. In particular, the low-energy metal-to-ligand charge-transfer transitions (MLCT) band in the visible absorption spectra of N719 is strongly affected, and locations of these MLCT bands revealed larger differences. The results indicate that there is a red shift of MLCT band in the spectra obtained by using TiO2nanocrystals with long morphology and large size compared to that in solution. And it produced a larger red-shift on the MLCT band after TiO2nanocrystals with small size mixed with some long nanocrystals. Accordingly, the utilization rate to visible light is increased. This is a reason why the DSC prepared by using such film as a photoelectrode has better performance than before mixing.

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