Laser photolysis of carboxylic acids in the gas phase: direct determination of the hydroxyl quantum yield at 222 nm

1990 ◽  
Vol 94 (2) ◽  
pp. 695-699 ◽  
Author(s):  
Donald L. Singleton ◽  
George. Paraskevopoulos ◽  
Robert S. Irwin
Keyword(s):  
Quantum Yield ◽  
Gas Phase ◽  
Carboxylic Acids ◽  
Direct Determination ◽  
Laser Photolysis

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

Laser photolysis of HNO3 at 222 nm: Direct determination of the primary quantum yield of OH

1986 ◽  
Vol 84 (12) ◽  
pp. 6662-6667 ◽  
Author(s):  
G. S. Jolly ◽  
D. L. Singleton ◽  
D. J. McKenney ◽  
G. Paraskevopoulos
Keyword(s):  
Quantum Yield ◽  
Direct Determination ◽  
Laser Photolysis

ChemInform Abstract: Laser Photolysis of HNO3at 222 nm: Direct Determination of the Primary Quantum Yield of OH.

1986 ◽  
Vol 17 (38) ◽  
Author(s):  
G. S. JOLLY ◽  
D. L. SINGLETON ◽  
D. J. MCKENNEY ◽  
G. PARASKEVOPOULOS
Keyword(s):  
Quantum Yield ◽  
Direct Determination ◽  
Laser Photolysis

Absolute chlorine atom quantum yield measurements in the UV and VUV gas-phase laser photolysis of CCl4

2003 ◽  
Vol 368 (3-4) ◽  
pp. 445-451 ◽  
Author(s):  
Alexander Hanf ◽  
Almuth Läuter ◽  
Hans-Robert Volpp
Keyword(s):  
Quantum Yield ◽  
Gas Phase ◽  
Chlorine Atom ◽  
Laser Photolysis

Near Infrared Spectroscopic Examination of Charred Pine Wood, Bark, Cellulose and Lignin: Implications for the Quantitative Determination of Charcoal in Soils

2007 ◽  
Vol 15 (5) ◽  
pp. 307-315 ◽  
Author(s):  
James B. Reeves ◽  
Gregory W. McCarty ◽  
David W. Rutherford ◽  
Robert L. Wershaw
Keyword(s):  
Carboxylic Acids ◽  
Infrared Spectra ◽  
Near Infrared ◽  
Direct Determination ◽  
Pine Wood ◽  
Oh Groups ◽  
Spectral Changes ◽  
Near Infrared Spectra ◽  
Material Temperature

The objective of this research was to investigate the effect of charring on near infrared spectra of materials likely to be present in forest fires in order to determine the feasibility of determining charred carbon in soils. Four materials (cellulose, lignin, pine bark and pine wood) and char from these materials created by charring for various durations (1 to 168 h) and at various temperatures (200 to 450°C) were studied. Near infrared spectra and measures of acidity (total acids, carboxylic acids, lactones and phenols as determined by titration) were available for 56 different samples (Not all samples charred at all temperatures/durations). Results showed spectral changes that varied with the material, temperature and duration of charring. Examination of spectra and correlation plots indicated that changes in the constituents of the materials in question, such as loss of OH groups in carbohydrates, rather than direct determination of typical products produced by charring, such as carboxylic acids, lactones and phenols, were the basis for the spectral changes. Finally, while the spectral changes resulting from charring appeared to be relatively unique to each material, PLS calibrations for total acids, carboxylic acids, lactones and phenols were successfully created (with R2 of 0.991, 0.943, 0.931 and 0.944, respectively) indicating that there is a sufficient commonality in the changes to develop calibrations without the need for unique calibrations for each specific set of charring conditions (i.e. material, temperature and time of heating).

A method for the direct determination of the rate constants for radical-radical interactions in the gas phase II. The rate constant for the recombination of methyl radicals

1957 ◽  
Vol 243 (1232) ◽  
pp. 130-142 ◽  
Keyword(s):  
Gas Phase ◽  
Rate Constant ◽  
Room Temperature ◽  
Direct Determination ◽  
Theoretical Interpretation ◽  
Methyl Radicals ◽  
Gas Phase Reactions ◽  
A Value ◽  
Acetone Vapour

The technique outlined in part I of this paper has been employed to study the photo­sensitized decomposition of acetone vapour. A theoretical interpretation of the non-stationary state applied to non-chain photochemical gas phase reactions with second-order termination has been given and the effects of non-homogeneous absorption of radiation have been considered. A value has been obtained for the rate constant for the recombination of methyl radicals in the gas phase at room temperature.

scholarly journals Direct determination of the kinetics of oxygen diffusion to the photocytes of a bioluminescent elaterid larva, measurement of gas- and aqueous-phase diffusional barriers and modelling of oxygen supply

2000 ◽  
Vol 203 (16) ◽  
pp. 2479-2484 ◽  
Author(s):  
G.S. Timmins ◽  
E.J. Bechara ◽  
H.M. Swartz
Keyword(s):  
Gas Phase ◽  
Aqueous Phase ◽  
Oxygen Diffusion ◽  
Time Course ◽  
Oxygen Supply ◽  
Direct Determination ◽  
Tracheal System ◽  
Significant Mechanism ◽  
Fluid Levels

We describe the development and use of a direct kinetic technique to determine the time taken for oxygen to diffuse from the external environment into the light-producing cells (photocytes) in the prothorax of bioluminescent larvae of Pyrearinus termitilluminans. This was achieved by measuring the time course of the pseudoflash induced through sequential anoxia followed by normoxia. We have also determined the separate times taken for this oxygen diffusion in gaseous and tissue (predominantly aqueous) phases by using helium and nitrogen as the carrier gas. Of the total time taken for diffusion, that in the gas phase required 613+/−136 ms (mean +/− s.e. m., N=5) whilst that in the aqueous phase required 1313+/−187 ms. These values imply pathlengths of diffusion in the gaseous and aqueous phases of 4.80×10(−)(3)+/−0.53×10(−)(3) and 8. 89×10(−)(5)+/−0.61×10(−)(5)m, respectively. In addition, the pathlength of gas-phase diffusion was used to derive a parameter relating to the tortuosity of the tracheal system. These values, together with those obtained upon bioluminescent oxygen consumption, have been used to model oxygen supply to the photocyte. From these studies, it would also appear that the modulation of tracheolar fluid levels might be a significant mechanism of control of tissue oxygen levels in at least some insects.

Sign in / Sign up

Export Citation Format

Share Document