Publications associées à Triplet oxygen

Bacterial inactivation in sunlit surface waters is dominated by reactive species that emanate from the synergy between light, iron, and natural organic matter

César Pulgarin, Stefanos Giannakis, Jun Ma, Da Wang, Shuang Song

In this study, the synergistic and antagonistic effects of Fe species and coexisting natural organic matter (NOM) on the efficacy of solar light disinfection of water are investigated. Different initial iron species (Fe2+/Fe3+) and naturalorganic matter ty ...

Elsevier2023

Single molecule fluorescence and phosphorescence studies using a scanning tunneling microscope

Abhishek Grewal

This thesis investigates novel single-molecule luminescence phenomena at their inherent, sub-molecular length scale. The microscopic understanding of luminescence processes will be crucial for the continued improvement of organic optoelectronic and semicon ...

EPFL2022

Photochemical oxidation of phenols and anilines mediated by phenoxyl radicals in aqueous solution

Urs von Gunten, Silvio Canonica, Stephanie Christa Remke

Reactive intermediates formed upon irradiation of chromophoric dissolved organic matter (CDOM) contribute to the degradation of various organic contaminants in surface waters. Besides well-studied "short-lived" photo oxidants, such as triplet state CDOM (3 ...

PERGAMON-ELSEVIER SCIENCE LTD2022

Identifying the mediators of intracellular E. coli inactivation under UVA light: The (photo) Fenton process and singlet oxygen

César Pulgarin, Stefanos Giannakis

Solar disinfection (SODIS) was probed for its underlying mechanism. When Escherichia coli was exposed to UVA irradiation, the dominant solar fraction acting in SODIS process, cells exhibited a shoulder before death ensued. This profile resembles cell killi ...

PERGAMON-ELSEVIER SCIENCE LTD2022

Optical properties and photochemical production of hydroxyl radical and singlet oxygen after ozonation of dissolved organic matter

Urs von Gunten, Frank Jonathan Leresche

This study focuses on the effects of ozonation on the optical and photochemical properties of dissolved organic matter (DOM). Upon ozonation, a decrease in light absorption properties of DOM was observed concomitantly with a large increase in singlet oxyge ...

ROYAL SOC CHEMISTRY2021

Phototransformation of Organic Contaminants in Aquatic Systems: Characterization of Long-Lived Photooxidants Derived from Dissolved Organic Matter

Stephanie Christa Remke

The increasing interest in the fate of organic contaminants in the aquatic environment requires the elucidation of relevant abiotic transformation processes. These processes often involve the ubiquitous dissolved organic matter (DOM), a complex mixture of ...

EPFL2021

Persulfate-Based Advanced Oxidation: Critical Assessment of Opportunities and Roadblocks

Urs von Gunten

Reports that promote persulfate-based advanced oxidation process (AOP) as a viable alternative to hydrogen peroxide-based processes have been rapidly accumulating in recent water treatment literature. Various strategies to activate peroxide bonds in persul ...

AMER CHEMICAL SOC2020

Molecular-Level Transformation of Dissolved Organic Matter during Oxidation by Ozone and Hydroxyl Radical

Urs von Gunten

Ozonation of drinking and wastewater relies on ozone (O-3) and hydroxyl radical ((OH)-O-center dot) as oxidants. Both oxidants react with dissolved organic matter (DOM) and alter its composition, but the selectivity of the two oxidants and mechanisms of re ...

AMER CHEMICAL SOC2020

Incidence of Quantum Confinement on Dark Triplet Excitons in Carbon Nanotubes

Ferenc Simon

The photophysics of single-wall carbon nanotubes (SWCNTs) is intensively studied due to their potential application in light harvesting and optoelectronics. Excited states of SWCNTs form strongly bound electron-hole pairs, excitons, of which only singlet e ...

2020

A systematic investigation on the bactericidal transient species generated by photo-sensitization of natural organic matter (NOM) during solar and photo Fenton disinfection of surface waters

César Pulgarin, Stefanos Giannakis, Mona Kohantorabi, Ling Feng

In this work, the role of dissolved oxygen in the solar and the photo-Fenton-mediated E. coli inactivation process was put under scrutiny. The effect of transient species that were produced in the presence of various natural organic matter isolates (NOM), ...

ELSEVIER SCIENCE BV2019

Kinetic modeling of lag times during photo-induced inactivation of E. coli in sunlit surface waters: Unraveling the pathways of exogenous action

César Pulgarin, Stefanos Giannakis, Jean Arnaud Troyon

This work presents a kinetic analysis of the exogenous photo-induced disinfection of E. coli in natural waters. Herein, the inactivation of bacteria by light and photo-generated transient species, i.e., hydroxyl radical (HO center dot), excited triplet sta ...

PERGAMON-ELSEVIER SCIENCE LTD2019

Reactions of aliphatic amines with ozone: Kinetics and mechanisms

Urs von Gunten, Sung Eun Lim

Aliphatic amines are common constituents in micropollutants and dissolved organic matter and present in elevated concentrations in wastewater-impacted source waters. Due to high reactivity, reactions of aliphatic amines with ozone are likely to occur durin ...

PERGAMON-ELSEVIER SCIENCE LTD2019

Gas-Phase Ozone Reactions with a Structurally Diverse Set of Molecules: Barrier Heights and Reaction Energies Evaluated by Coupled Cluster and Density Functional Theory Calculations

Jeremy Samuel Arey, Peter Rudolf Tentscher, Daniela Trogolo

Reactions with ozone transform organic and inorganic molecules in water treatment systems as well as in atmospheric chemistry, either in the aqueous phase, at gas/particle interfaces, or in the gas phase. Computed thermokinetic data can be used to estimate ...

AMER CHEMICAL SOC2019

Effects of Ozone on the Photochemical and Photophysical Properties of Dissolved Organic Matter

Urs von Gunten, Frank Jonathan Leresche, Silvio Canonica

This study focused on the effects of ozonation on the photochemical and photophysical properties of dissolved organic matter (DOM). Upon ozonation, a decrease in DOM absorbance was observed in parallel with an increase in singlet oxygen (O-1(2)) and fluore ...

AMER CHEMICAL SOC2019

Photoinduced disinfection in sunlit natural waters: Measurement of the second order inactivation rate constants between E-coli and photogenerated transient species

César Pulgarin, Stefanos Giannakis, Jean Arnaud Troyon

This work uncovers the implications of the estimation of exogenous inactivation rates for E. coli after the initial lag phase, and presents a strategy for the determination of the second-order inactivation rate constants (k2nd) of these bacteria with relev ...

PERGAMON-ELSEVIER SCIENCE LTD2018

Conservation of vibrational coherence in ultrafast electronic relaxation: The case of diplatinum complexes in solution

Majed Chergui, Dominik Kinschel, Gerald Auböck, Roberto Monni, Kathrin Maria Aziz-Lange

We report the results of ultrafast transient absorption studies of tetrakis(l-pyrophosphito) diplatinate(II), Pt-2(mu-P(2)O(5)H2)(4) (Pt(pop)) and its perfluoroborated derivative Pt-2(mu-P2O5(BF2)(4) (Pt(pop-BF2)) in water and acetonitrile upon e ...

Elsevier2017

Phototransformation of Acesulfame K in surface waters: Comparison of two techniques for the measurement of the second-order rate constants of indirect photodegradation, and modelling of photoreaction kinetics

Stefanos Giannakis

By use of photochemical modelling we show that acesulfame K (ACE) can undergo photodegradation in surface waters, mainly by reaction with (OH)-O-center dot and possibly (CDOM)-C-3* (the triplet states of chromophoric dissolved organic matter). With the pos ...

Elsevier2017

Origin of the Spin-Orbital Liquid State in a Nearly J=0 Iridate Ba3ZnIr2O9

Henrik Moodysson Rønnow, Martin Mansson, Paul Gregory Freeman

We show using detailed magnetic and thermodynamic studies and theoretical calculations that the ground state of Ba3ZnIr2O9 is a realization of a novel spin-orbital liquid state. Our results reveal that Ba3ZnIr2O9 with Ir5+ (5d(4)) ions and strong spin-orbi ...

2016

Investigations of the non-adiabatic photophysics of Cu(I)-phenanthroline complexes

Gloria Capano

Cu(I)-phenanthrolines are an important class of metal-organic molecules that exhibits much promise for solar energy harvesting and solar-driven catalysis applications. Although many experimental studies have been performed calling for high-level simulation ...

EPFL2016

Photonic contacting of gas-liquid phases in a falling film microreactor for continuous-flow photochemical catalysis with visible light

Albert Renken

A microstructured falling film reactor was applied to the dye-sensitized photochemical conversion of 1,5-dihydroxynaphthalene to juglone. This continuous-flow microreactor enables the efficient contacting of a gas and a liquid phase in combination with ext ...

Royal Soc Chemistry2016