Long-wavelength absorption by fractal dust grains

It was found that the long-wavelength absorption band of the laser dye IR 1061 and its analogue with an unsubstituted polymethine chain is strongly broadened and decreases in intensity in polar solvents, while the fluorescence band remains narrow and practically does not change in a wide range of solvent polarities. Based on the quantum-chemical calculations of these dyes by the ab initio DFT/B3LYP/6-31G (d,p) and TDDFT methods, taking into account the polarity of the medium by the PCM method, it is shown that the reason for this difference is the weakening of solvation in the fluorescent state as compared to the ground state due to the greater equalization of the charge in the first than in the latter. An increase in the alternation of bond orders in the polymethine chain in the fluorescent state was found, which causes an increase of vibronic interactions in the radiative transition as compared to the absorptive one. Spectral effects caused by a change in the angle of rotation of phenyl groups in the thiopyrylium cycle upon excitation have been analyzed.

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Erstmaliger Nachweis von π–π Dimerenbildung bei stabilen 1,4-Dialkylchinoxalinium-Radikalkationen. Struktur, Spektroskopie und Magnetismus / First Evidence for π-π-Dimerization of the Stable 1,4-Dialkylquinoxalinium Radical Cations. Structure, Spectroscopy and Magnetism

Zeitschrift für Naturforschung B ◽

10.1515/znb-1993-0905 ◽

1993 ◽

Vol 48 (9) ◽

pp. 1181-1186 ◽

Cited By ~ 7

Author(s):

H.-D. Hausen ◽

Wolfgang Kaim ◽

Andreas Schulz ◽

Michael Moscherosch ◽

Jeanne Jordanov

Keyword(s):

Solid State ◽

Magnetic Measurements ◽

Magnetic Moments ◽

Cation Radical ◽

Radical Cations ◽

Long Wavelength ◽

Wavelength Absorption ◽

Molecular Structure Analysis ◽

Long Wavelength Absorption Band ◽

Quinoxaline Ring

Crystal and molecular structure analysis of 1,4-diethylquinoxalinium iodide shows a virtually planar quinoxaline ring with 11 conjugated π-electrons. In contrast to the triiodide of the 1,4,6,7-tetramethyl derivative or to the tetraphenylborate salt of 1,4-diethylquinoxalinium cation radical the iodide exhibits π-π-dimerized radical cations in the solid state with synplanar ethyl groups and a rather small intermolecular distance of about 315 pm between the π-planes of the primarily interacting 1,4-diazine rings. Solid state magnetic measurements between 2 and 300 K show considerably diminished magnetic moments due to partial spin-pairing, and UV/VIS spectroscopic measurements in acetonitrile reflect the π—π-interaction in solution through the appearance of a long-wavelength absorption band.

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Non-Thermal and Dust Charge Effects on Surface Ion Waves in Semi-Bound Lorentzian Plasmas

Zeitschrift für Naturforschung A ◽

10.1515/zna-2006-7-803 ◽

2006 ◽

Vol 61 (7-8) ◽

pp. 323-329 ◽

Cited By ~ 1

Author(s):

Jae-Hoon Song ◽

Young-Dae Jung

Keyword(s):

Surface Wave ◽

Phase Velocity ◽

Spectral Index ◽

Charged Dust ◽

Dust Grains ◽

Charge Effects ◽

Long Wavelength ◽

Dust Charge ◽

Ion Waves ◽

Positively Charged

The non-thermal and dust charge effects on a surface electrostatic ion plasma wave are investigated in a semi-bound magnetized dusty Lorentzian plasma. The results show that the phase velocity of the surface wave with negatively charged dust grains is greater than that with positively charged dust grains or that with neutral dust grains. It is also found that the phase velocity increases with increasing the spectral index of the plasma. For the long wavelength domain, however, the phase velocity of the surface wave is found to be almost independent of the spectral index.

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High Temperature, High Pressure Absorption Spectra of Uranyl Chloride Solutions Under Shock Conditions

MRS Proceedings ◽

10.1557/proc-22-161 ◽

1983 ◽

Vol 22 ◽

Author(s):

Arnold H. Ewald

Keyword(s):

Shock Wave ◽

Absorption Spectra ◽

Room Temperature ◽

Nitrate Solution ◽

Appreciable Effect ◽

Long Wavelength ◽

Uranyl Perchlorate ◽

Wavelength Absorption ◽

High Temperature High Pressure ◽

Absorption Measurements

In 1960 David and Ewald [1] developed a technique for photographing the absorption spectra of solutions under shock wave conditions. A photograph of the spectrum of a uranyl nitrate solution exposed to a shock wave of 75 kbar showed the absorption to extend beyond 500 nm, the long wavelength limit for uranyl solutions under ordinary conditions. A.H. Ewald (unpublished, 1963) found that at room temperature pressure up to 6 kbar had no appreciable effect on absorption. Bell and Biggers [2,3] published an analysis of the spectrum of uranyl perchlorate solutions. The longest wavelength absorption band was at 486 nm but Bell [4] later found bands at 508 and 531 nm. The intensity of these very weak bands increased when the solution was heated to 95° C, and they were interpreted as “hot bands” due to absorption from an excited ground state. This paper reports new absorption measurements made on uranyl solutions heated to 250°C at low pressure and offers an interpretation of the effect observed in the shock experiments.

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Functional group and substituent effects, both steric and electronic, upon the ultraviolet absorption spectra of some N-alkyl- and N,N-dialkyl-derivatives of some cinnamamides and benzalcyanoacetamides

Canadian Journal of Chemistry ◽

10.1139/v69-544 ◽

1969 ◽

Vol 47 (17) ◽

pp. 3278-3280 ◽

Cited By ~ 2

Author(s):

A. D. Delaney ◽

D. J. Currie ◽

H. L. Holmes

Keyword(s):

Hydrogen Atom ◽

Absorption Spectra ◽

Functional Group ◽

Substituent Effects ◽

Ultraviolet Absorption ◽

Long Wavelength ◽

Wavelength Absorption ◽

Derivatives Of

Conjugative and steric constants for N-substituted carboxyamide groups have been derived which allow the calculation of the long wavelength absorption maxima of N-alkyl- and N,N-dialkyl-derivatives of cinnamamide and benzalcyanoacetamide. Deviations between calculated and observed values indicate that there may be steric interference between bulky N,N-dialkylcarboxyamide groups and the benzylic hydrogen atom.

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Elaboration of an unexplored substitution site in synthetic bacteriochlorins

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424615500534 ◽

2015 ◽

Vol 19 (07) ◽

pp. 887-902 ◽

Cited By ~ 4

Author(s):

Nuonuo Zhang ◽

Kanumuri Ramesh Reddy ◽

Jianbing Jiang ◽

Masahiko Taniguchi ◽

Roger D. Sommer ◽

...

Keyword(s):

Bathochromic Shift ◽

Fluorescence Emission ◽

Bacterial Photosynthesis ◽

Alkoxy Group ◽

The Self ◽

X Ray ◽

Long Wavelength ◽

Substitution Site ◽

Wavelength Absorption ◽

Long Wavelength Absorption Band

The ability to introduce substituents at designated sites about the perimeter of synthetic bacteriochlorins – analogs of bacteriochlorophylls of bacterial photosynthesis – remains a subject of ongoing study. Here, the self-condensation of a dihydrodipyrrin-dioxolane affords a 5-[2-(trimethylsiloxy)ethoxy]bacteriochlorin. Like a 5-methoxybacteriochlorin, the latter undergoes regioselective bromination at the 15-position, directed by the distal 5-alkoxy group. On the other hand, attempted bromination of a bacteriochlorin bearing a 5-(2-hydroxyethoxy) group resulted in intramolecular ether formation with the adjacent β-pyrroline position to give an annulated dioxepine ring (confirmed by single-crystal X-ray structural analysis). The hydroxyethoxy group at the 5-position can be derivatized by acylation. In addition, the installation of auxochromes (methoxycarbonyl, phenylethynyl) at the β-pyrrole rings causes a substantial bathochromic shift of the long-wavelength absorption band (812 nm) and companion fluorescence emission band (821 nm). Taken together, the modification of the 5-substituent complements existing methods for installing a single substituent on the bacteriochlorin macrocycle.

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Comparison of short and long wavelength absorption electron donor materials in C60-based planar heterojunction organic photovoltaics

Organic Electronics ◽

10.1016/j.orgel.2012.06.006 ◽

2012 ◽

Vol 13 (10) ◽

pp. 2118-2129 ◽

Cited By ~ 11

Author(s):

Shun-Wei Liu ◽

Wei-Cheng Su ◽

Chih-Chien Lee ◽

Chi-Feng Lin ◽

Shih-Chieh Yeh ◽

...

Keyword(s):

Electron Donor ◽

Organic Photovoltaics ◽

Long Wavelength ◽

Wavelength Absorption ◽

Planar Heterojunction

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Synthesis and spectroscopic properties of benzo- and naphthofuryl-3-hydroxychromones

Canadian Journal of Chemistry ◽

10.1139/v01-066 ◽

2001 ◽

Vol 79 (4) ◽

pp. 358-363 ◽

Cited By ~ 36

Author(s):

Andrey S Klymchenko ◽

Turan Ozturk ◽

Vasyl G Pivovarenko ◽

Alexander P Demchenko

Keyword(s):

Excited State ◽

Proton Transfer ◽

Spectroscopic Properties ◽

Molecular Probe ◽

Absorption Bands ◽

Methyl Group ◽

Long Wavelength ◽

Excited State Proton Transfer ◽

Wavelength Absorption ◽

Long Wavelength Absorption Band

With the focus of designing new fluorescent probes, four new 3-hydroxy-chromone derivatives bearing benzofuran and naphthofuran groups were synthesized. They show bathochromic absorption shifts relative to 3-hydroxyflavone with the ability of retention to display the excited-state proton transfer. Disruption of the planarity by the methyl group in the furan ring leads to a decrease of both the extinction coefficient and the contribution of long wavelength absorption band, while molecules without a methyl group showed two distinct absorption bands. Shifts to longer wavelengths are also observed in fluorescent spectra, and the absence of the methyl group results in a dramatic increase of fluorescence quantum yield and lifetime. Of the extended 3-hydroxychromone derivatives, 3-hydroxy-2-naphtho[2,1-b]furan-2-yl-chromone has shown comparable, and in some cases better, absorption and fluorescence properties than the 3-hydroxychromones synthesized so far, which make it a highly promising candidate as molecular probe for analytical chemistry, biophysics, and cellular biology.Key words: benzo- and naphthofuryl-3-hydroxyflavone, synthesis, electronic spectra, fluorescence, excited state proton transfer.

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Development of Hydrogenated Microcrystalline Silicon-Germanium Alloys for Improving Long-Wavelength Absorption in Si-Based Thin-Film Solar Cells

International Journal of Photoenergy ◽

10.1155/2014/579176 ◽

2014 ◽

Vol 2014 ◽

pp. 1-7 ◽

Cited By ~ 2

Author(s):

Yen-Tang Huang ◽

Hung-Jung Hsu ◽

Shin-Wei Liang ◽

Cheng-Hang Hsu ◽

Chuang-Chuang Tsai

Keyword(s):

Thin Film ◽

Solar Cells ◽

Silicon Germanium ◽

Volume Fraction ◽

Thin Film Solar Cells ◽

Crystalline Volume Fraction ◽

Microcrystalline Silicon ◽

Single Junction ◽

Long Wavelength ◽

Wavelength Absorption

Hydrogenated microcrystalline silicon-germanium (μc-Si1-xGex:H) alloys were developed for application in Si-based thin-film solar cells. The effects of thegermane concentration(RGeH4)and thehydrogen ratio(RH2)on theμc-Si1-xGex:H alloys and the corresponding single-junction thin-film solar cells were studied. The behaviors of Ge incorporation in a-Si1-xGex:H andμc-Si1-xGex:H were also compared. Similar to a-Si1-xGex:H, the preferential Ge incorporation was observed inμc-Si1-xGex:H. Moreover, a higherRH2significantly promoted Ge incorporation for a-Si1-xGex:H, while the Ge content was not affected byRH2inμc-Si1-xGex:H growth. Furthermore, to eliminate the crystallization effect, the 0.9 μm thick absorbers with a similar crystalline volume fraction were applied. With the increasingRGeH4, the accompanied increase in Ge content ofμc-Si1-xGex:H narrowed the bandgap and markedly enhanced the long-wavelength absorption. However, the bias-dependent EQE measurement revealed that too much Ge incorporation in absorber deteriorated carrier collection and cell performance. With the optimization ofRH2andRGeH4, the single-junctionμc-Si1-xGex:H cell achieved an efficiency of 5.48%, corresponding to the crystalline volume fraction of 50.5% and Ge content of 13.2 at.%. Compared toμc-Si:H cell, the external quantum efficiency at 800 nm had a relative increase by 33.1%.

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