An experimental methodology to measure the reaction rate constants of processes sensitised by the triplet state of 4-carboxybenzophenone as a proxy of the triplet states of chromophoric dissolved organic matter, under steady-state irradiation conditions

2018 ◽  
Vol 20 (7) ◽  
pp. 1007-1019 ◽  
Author(s):  
Marco Minella ◽  
Lorenzo Rapa ◽  
Luca Carena ◽  
Marco Pazzi ◽  
Valter Maurino ◽  
...  
Keyword(s):  
Organic Matter ◽  
Steady State ◽  
Dissolved Organic Matter ◽  
Triplet State ◽  
Rate Constants ◽  
Reaction Rate ◽  
Experimental Methodology ◽  
Chromophoric Dissolved Organic Matter ◽  
Triplet States ◽  
Reaction Rate Constants

This is an assessment of the reactivity of 4-carboxybenzophenone under steady-state irradiation.

scholarly journals Triplet State Formation of Chromophoric Dissolved Organic Matter in Atmospheric Aerosols: Characteristics and Implications

2020 ◽  
Author(s):  
Qingcai Chen ◽  
Zhen Mu ◽  
Li Xu ◽  
Mamin Wang ◽  
Jin Wang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Triplet State ◽  
Atmospheric Aerosols ◽  
Formation Rate ◽  
Chromophoric Dissolved Organic Matter ◽  
Biomass Combustion ◽  
Triplet States ◽  
Ambient Aerosols ◽  
Paramagnetic Resonance

Abstract. There is chromophore dissolved organic matter (CDOM) in the atmosphere, which may form triplet-state chromophoric dissolved organic matter (3CDOM*) to further driving the formation of reactive oxygen species (ROS) under solar illumination. 3CDOM* contributes significantly to aerosol photochemistry and plays an important role in aerosol aging. We quantify the ability to form 3CDOM* and drive the formation of ROS by primary, secondary and ambient aerosols. Biomass combustion has the strongest 3CDOM* generation capacity and the weakest vehicle emission capacity. Ambient aerosol has a stronger ability to generate 3CDOM* in winter than in summer. Most of the triplet states generation conform to first-order reaction, but some of them do not due to the different quenching mechanism. The structural-activity relationship between the CDOM type and the 3CDOM* formation capacity shows that the two types of CDOM identified, which similar to the nitrogen-containing chromophores contributed 88 % to the formation of 3CDOM*. The estimated formation rate of 3CDOM* can reach ~ 100 μmol m−3 h−1 in the atmosphere in Xi'an, China, which is approximately one hundred thousand-times the hydroxyl radical (•OH) production. This study verified that 3CDOM* drives at least 30 % of the singlet oxygen (1O2) and 31 % of the •OH formed by aerosols using the spin trapping and electron paramagnetic resonance technique.

Photometric hydroxyl radical scavenging analysis of standard natural organic matter isolates

2014 ◽  
Vol 16 (4) ◽  
pp. 764-769 ◽  
Author(s):  
J. E. Donham ◽  
E. J. Rosenfeldt ◽  
K. R. Wigginton
Keyword(s):  
Organic Matter ◽  
Hydroxyl Radical ◽  
Natural Organic Matter ◽  
Rate Constants ◽  
Reaction Rate ◽  
Radical Scavenging ◽  
Reaction Rate Constants

Hydroxyl radical (˙OH) scavenging reaction rate constants of standard natural organic matter (NOM) isolates (k˙OH,NOM) were measured with a rapid background scavenging method.

Reaction rate constants in steady‐state hollow cathode discharges: N2+ H2O reactions

1974 ◽  
Vol 61 (3) ◽  
pp. 1180-1188 ◽  
Author(s):  
F. Howorka ◽  
W. Lindinger ◽  
Robert N. Varney
Keyword(s):  
Steady State ◽  
Hollow Cathode ◽  
Rate Constants ◽  
Reaction Rate ◽  
Reaction Rate Constants

EFFECT OF FLUCTUATIONS OF FREE RADICAL CONCENTRATIONS ON THE CALCULATION OF RELATIVE RATE CONSTANTS

1954 ◽  
Vol 32 (2) ◽  
pp. 63-70 ◽  
Author(s):  
R J Cvetanović ◽  
E. Whittle
Keyword(s):  
Steady State ◽  
Free Radical ◽  
Rate Constants ◽  
Reaction Rate ◽  
Relative Rate ◽  
Reaction Rate Constants ◽  
Idealized Model ◽  
Relative Rate Constants

The effect of fluctuations in free radical concentrations on the values of relative reaction rate constants calculated from steady state expressions has been evaluated for a number of idealized model cases, representative of various conditions usually encountered in experiments.

scholarly journals Triplet state dissolved organic matter in aquatic photochemistry: reaction mechanisms, substrate scope, and photophysical properties

2016 ◽  
Vol 18 (11) ◽  
pp. 1381-1399 ◽  
Author(s):  
Kristopher McNeill ◽  
Silvio Canonica
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Surface Waters ◽  
Reaction Mechanisms ◽  
Photophysical Properties ◽  
Chromophoric Dissolved Organic Matter ◽  
Triplet States ◽  
Excited Triplet ◽  
Aquatic Photochemistry ◽  
Excited Triplet States

Excited triplet states of chromophoric dissolved organic matter (3CDOM*) play a major role among the reactive intermediates produced upon absorption of sunlight by surface waters.

scholarly journals Binding of Calcium and Magnesium Ions to Chromophoric Dissolved Organic Matter (CDOM): A Combination of Steady-State and Time-Resolved Fluoresce Study

2021 ◽  
Author(s):  
Xu Zhang ◽  
Juan Liu ◽  
Ruiya Zhou
Keyword(s):  
Organic Matter ◽  
Steady State ◽  
Fluorescence Quenching ◽  
Dissolved Organic Matter ◽  
Fluorescence Decay ◽  
Chromophoric Dissolved Organic Matter ◽  
Time Resolved ◽  
Water Composition ◽  
Terrestrial Source ◽  
Order Of Magnitude

Revealing the binding properties of calcium ion (Ca2+) and magnesium ion (Mg2+) to chromophoric dissolved organic matter (CDOM) facilities understanding the effect of natural water composition on the photophysics of dissolved organic matter. Steady-state and time-resolved fluorescence spectrometry, and dynamic light scattering were applied to investigate the fluorescence quenching process of CODM by Ca2+ and Mg2+. The binding of Ca2+ and Mg2+ preferred terrestrial CDOM to aquatic CDOM. The fluorescence quenching of CDOM by cations mainly occurred in a static process, which was based on the fact that the decrease of steady-state fluorescence intensity was greater than fluorescence lifetime. The fluorescence quenching was profound under longer excitation and emission wavelength. The binding constant (K, L/mol) for Ca2+ to CDOM from terrestrial source ranged from 4.29 to 5.09 (lgK), which was approximately one order of magnitude higher than that of Mg2+ to CDOM (3.86 to 4.56). Fluorescence decay became faster in the presence of Ca2+ and Mg2+. Lifetime distribution of CDOM excited states shifted to small value side in the presence of metal ions, particularly for Ca2+, indicating fluorescence quenching of CDOM mainly through the interaction of Ca2+/Mg2+ with relatively long-lived fluorophores.

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