Triplet quantum yields in light-scattering powder samples measured by laser-induced optoacoustic spectroscopy (LIOAS)

2012 ◽  
Vol 11 (6) ◽  
pp. 1010 ◽  
Author(s):  
Eugenia P. Tomasini ◽  
Silvia E. Braslavsky ◽  
Enrique San Román
Keyword(s):  
Light Scattering ◽  
Quantum Yields ◽  
Optoacoustic Spectroscopy ◽  
Powder Samples ◽  
Triplet Quantum Yields

Validation of Fluorescence Quantum Yields for Light-Scattering Powdered Samples by Laser-Induced Optoacoustic Spectroscopy

Langmuir ◽  
2009 ◽  
Vol 25 (10) ◽  
pp. 5861-5868 ◽  
Author(s):  
Eugenia P. Tomasini ◽  
Enrique San Román ◽  
Silvia E. Braslavsky
Keyword(s):  
Light Scattering ◽  
Quantum Yields ◽  
Fluorescence Quantum Yields ◽  
Optoacoustic Spectroscopy

scholarly journals Similar chemical structures, dissimilar triplet quantum yields: a CASPT2 model rationalizing the trend of triplet quantum yields in nitroaromatic systems

2019 ◽  
Vol 21 (20) ◽  
pp. 10514-10522 ◽  
Author(s):  
Angelo Giussani ◽  
Graham A. Worth
Keyword(s):  
Quantum Yields ◽  
Chemical Structures ◽  
Similar Chemical ◽  
Triplet Quantum Yields

S1/S0 accessibility strongly influences the triplet quantum yields of nitronaphthalenes.

Spectrofluorometric studies. VIII. The effect of CO2 and CHCl3 on the photochemistry of monofluorobenzene

1970 ◽  
Vol 48 (10) ◽  
pp. 1607-1613 ◽  
Author(s):  
M. E. MacBeath ◽  
I. Unger
Keyword(s):  
Quantum Yield ◽  
Quantum Yields ◽  
Vibrationally Excited ◽  
Excited Triplet ◽  
Improved Technique ◽  
Triplet Quantum Yields

The sensitized emission of biacetyl technique was used to study the effect of CHCl3 and CO2 on the triplet quantum yields of both benzene and monofluorobenzene.The monofluorobenzene was studied at λ excitation (λex) of 2470, 2590, and 2670 Å. At 2470 Å, the triplet yield increased by over 40% with both added gases; at λex 2590 Å, by around 30%; and at λex 2670 Å, about 20%. CHCl3 is slightly more effective than CO2 in enhancing the biacetyl phosphorescent yield. The quantum yield of fluorescence was unchanged with these added gases. Using a slightly improved technique, the comparison irradiation of a benzene–biacetyl mixture at λex 2540 Å with added CHCl3 was repeated. The results confirmed that the biacetyl phosphorescent yield decreased with increasing pressures of CHCl3, but suggest that the effect is not as great as previously reported. At the same wavelength, the triplet yield is unaffected by the addition of CO2. The quantum yield of fluorescence of benzene is virtually unaffected by the added gases. The data suggest that in the monofluorobenzene case the CO2 and CHCl3 are quenching vibrationally excited triplet fluorobenzene molecules.

Quantitative Determination of Photokinetic Parameters for Reversible Photoisomerizations in Light Scattering Adsorbent-Adsorbates

2000 ◽  
Vol 214 (2) ◽  
Author(s):  
R. Gade ◽  
Th. Porada
Keyword(s):  
Approximate Solution ◽  
Light Scattering ◽  
Quantum Yield ◽  
Present Method ◽  
Irradiation Time ◽  
Initial Slope ◽  
Quantum Yields ◽  
Absorption Coefficients ◽  
Actinic Light

Based on an approximate solution of the differential equations describing the rate of a reversible photoisomerization and the attenuation of the actinic light in a powdered adsorbent-adsorbate a method is presented permitting us to predict the irradiation time dependence of the sample reflectance and to determine both the quantum yields of the partial reactions and the absorption coefficients of the reactant and the product from the reflectance-time-curves measured at two different wavelengths. The present method, thus, is an improved version of the peviously reported procedure [1] which enables the quantum yield of a simple photoreaction to be calculated from the initial slope of the R(

Effect of aggregation of a cationic phthalocyanine in micelles and in the presence of human serum albumin

2006 ◽  
Vol 10 (01) ◽  
pp. 33-42 ◽  
Author(s):  
Myriam E. Rodriguez ◽  
Daniel A. Fernández ◽  
Josefina Awruch ◽  
Silvia E. Braslavsky ◽  
Lelia E. Dicelio
Keyword(s):  
Human Serum Albumin ◽  
Serum Albumin ◽  
Human Serum ◽  
Hydrophobic Interactions ◽  
Photophysical Properties ◽  
Sodium Dodecylsulfate ◽  
Water Soluble ◽  
Quantum Yields ◽  
Ionic Interactions ◽  
Triplet Quantum Yields

The photophysical properties of tetrakis(1,1-dimethyl-2-trimethylammonium)ethylphthalocyaninato zinc(II) tetraiodide (I) – a water-soluble cationic phthalocyanine – are presented in the presence of human serum albumin (HSA) and in micelles of sodium dodecylsulfate ( SDS ) and hexadecyltrimethylammonium chloride ( CTAC ). Spectrophotometric measurements showed that the surfactants SDS and CTAC induce monomerization of I, although the latter less efficiently than the former. This effect is less pronounced in the presence of HSA. The strength of this effect is evaluated through dimerization constants, which are Kd = (5 ± 1) × 105 m−1 in SDS , (1.5 ± 0.5) × 106 M −1 in CTAC , and (1.8 ± 0.9) × 106 M −1 in HSA. Fluorescence experiments confirm that aggregation of I drops as the concentration of surfactant is raised. Triplet quantum yields also decreased upon aggregation and were Φ T = 0.59, 0.16, and < 0.01 in SDS , CTAC , and HSA, respectively. These results indicate that the affinity of I for the environment is not just due to ionic interactions; hydrophobic interactions play an equally important role.

LASER INTENSITY AND THE COMPARATIVE METHOD FOR DETERMINATION OF TRIPLET QUANTUM YIELDS

1978 ◽  
Vol 28 (2) ◽  
pp. 277-281 ◽  
Author(s):  
R. Bensasson ◽  
C. R. Goldschmidt ◽  
E. J. Land ◽  
T. G. Truscott
Keyword(s):  
Laser Intensity ◽  
Comparative Method ◽  
Quantum Yields ◽  
Triplet Quantum Yields

Tetra and octa(2,6-di-iso-propylphenoxy)-substituted phthalocyanines: a comparative study among their photophysicochemical properties

2012 ◽  
Vol 16 (01) ◽  
pp. 163-174 ◽  
Author(s):  
Ahmad Tuhl ◽  
Wadzanai Chidawanayika ◽  
Hamada Mohamed Ibrahim ◽  
Nouria Al-Awadi ◽  
Christian Litwinski ◽  
...  
Keyword(s):  
Fine Tuning ◽  
Quantum Yields ◽  
Steric Interaction ◽  
Fluorescence Quantum Yields ◽  
H Nmr ◽  
Derivative Series ◽  
Uv Visible ◽  
Almost All ◽  
Triplet Quantum Yields ◽  
Triplet Lifetime

This work reports on the synthesis of novel metal free, zinc, aluminum, gallium and indium tetra and octa (2,6-di-iso-propylphenoxy)-substituted phthalocyanine derivatives. UV-visible and 1H NMR analyses confirm that a non-planar conformation, adapted by the phenoxy substituents due to steric interaction in both derivative series, perfectly discourage cofacial aggregation. Fluorescence quantum yields vary as a function of the number of substituents on the ring periphery, while the fluorescence lifetimes display no distinct trend. Triplet quantum yields are significantly larger for the tetra 2,6-di-iso-propylphenoxy- substituted derivatives relative to their corresponding octa-substituted species. However there was no overall trend in the triplet lifetime values. For almost all of the phthalocyanine derivatives, singlet oxygen was produced with relatively good quantum yields. This study explores the possibility of fine-tuning their physicochemical properties by simple structural modification.

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