Determination of the Quantum Yield for the Photochemical Generation of Hydroxyl Radicals in TiO2Suspensions

1996 ◽  
Vol 100 (10) ◽  
pp. 4127-4134 ◽  
Author(s):  
Lizhong Sun ◽  
James R. Bolton
Keyword(s):  
Quantum Yield ◽  
Hydroxyl Radicals ◽  
Photochemical Generation

Direct determination of the quantum yield of hydroxyl radicals in the laser photolysis of formic acid at 222 nm

1987 ◽  
Vol 91 (13) ◽  
pp. 3463-3465 ◽  
Author(s):  
Gurvinder S. Jolly ◽  
Donald L. Singleton ◽  
George. Paraskevopoulos
Keyword(s):  
Quantum Yield ◽  
Formic Acid ◽  
Hydroxyl Radicals ◽  
Direct Determination ◽  
Laser Photolysis

Determination of photonic efficiency and quantum yield of formaldehyde formation in the presence of various TiO2 photocatalysts

2001 ◽  
Vol 44 (5) ◽  
pp. 279-286 ◽  
Author(s):  
C. Wang ◽  
D.W. Bahnemann ◽  
J.K. Dohrmann
Keyword(s):  
Quantum Yield ◽  
Hydroxyl Radicals ◽  
Critical Concentration ◽  
Photon Flux ◽  
Tio2 Photocatalysts ◽  
Ph Values ◽  
Optimum Ph ◽  
Photonic Efficiency ◽  
True Quantum

Illumination of aqueous TiO2 suspentions yields hydroxyl radicals, which can be trapped by methanol producing formaldehyde (HCHO). In this work, the photonic efficiency and quantum yield of HCHO formation in colloidal TiO2 solutions and, P25 and UV 100 suspensions have been determined. Differences in photocatalytic activity of the three photocatalysts have been found and are discussed. The photonic efficiency of HCHO formation in the presence of P25 and UV 100 depends on the concentration of TiO2 and the pH. The critical concentration is 2.5 g/L. Below this, the photonic efficiency with P 25 is higher than with UV 100, and vice versa. Optimum pH values for P25 and UV 100 giving the maximum photonic efficiency are 7.7 and 10.4, respectively. Compared to P25 and UV 100, the true quantum yield of HCHO formation in colloidal TiO2 solution varies a little with pH and virtually does not change with the amount of loading of TiO2. The true quantum yield varies as the inverse square root of light intensity. The quantum yield increases from 0.02 to 0.08 when the absorbed photon flux decreases from 8.1 × 10-7 Ein/L s to 4.9 × 10-8 Ein/L s. A simple model is presented to explain the experimental observation.

scholarly journals Quantitative Determination of Dark Chromophore Population Explains the Apparent Low Quantum Yield of Red Fluorescent Proteins

2020 ◽  
Vol 124 (8) ◽  
pp. 1383-1391 ◽  
Author(s):  
Jord C. Prangsma ◽  
Robert Molenaar ◽  
Laura van Weeren ◽  
Daphne S. Bindels ◽  
Lindsay Haarbosch ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Quantitative Determination ◽  
Fluorescent Proteins ◽  
Red Fluorescent Proteins

Determination of the quantum yield of singlet oxygen sensitized by halogenated boron difluoride dipyrromethenes

2017 ◽  
Vol 51 (3) ◽  
pp. 175-181 ◽  
Author(s):  
R. T. Kuznetsova ◽  
Iu. V. Aksenova ◽  
D. E. Bashkirtsev ◽  
A. S. Shulev ◽  
E. V. Antina ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Singlet Oxygen ◽  
Boron Difluoride

Terminology, relative photonic efficiencies and quantum yields in heterogeneous photocatalysis. Part II: Experimental determination of quantum yields

1999 ◽  
Vol 71 (2) ◽  
pp. 321-335 ◽  
Author(s):  
Angela Salinaro ◽  
Alexei V. Emeline ◽  
Jincai Zhao ◽  
Hisao Hidaka ◽  
Vladimir K. Ryabchuk ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Visible Region ◽  
Heterogeneous Photocatalysis ◽  
Quantum Yields ◽  
Yield Data ◽  
Normal Absorption ◽  
The One ◽  
Solid Liquid ◽  
Photonic Efficiency

In the preceding article [Serpone and Salinaro, Pure Appl. Chem., 71(2), 303-320 (1999)] we examined two principal features of heterogeneous photocatalysis that demanded scrutiny: (i) description of photocatalysis and (ii) description of process efficiencies. For the latter we proposed a protocol relative photonic efficiency which could subsequently be converted to quantum yields. A difficulty in expressing a quantum yield in heterogeneous photochemistry is the very nature of the system, either solid/liquid or solid/gas, which places severe restrictions on measurement of the photon flow absorbed by the light harvesting component, herein the photocatalyst TiO2, owing to non-negligible scattering by the particulates. It was imperative therefore to examine the extent of this problem. Extinction and absorption spectra of TiO2 dispersions were determined at low titania loadings by normal absorption spectroscopy and by an integrated sphere method, respectively, to assess the extent of light scattering. The method is compared to the one reported by Grela et al. [J. Phys. Chem., 100, 16940 (1996)] who used a polynomial extrapolation of the light scattered in the visible region into the UV region where TiO2 absorbs significantly. This extrapolation underestimates the scattering component present in the extinction spectra, and will no doubt affect the accuracy of the quantum yield data. Further, we report additional details in assessing limiting photonic efficiencies and quantum yields in heterogeneous photocatalysis.

Sign in / Sign up

Export Citation Format

Share Document