The role of humic acid aggregation on the kinetics of photosensitized singlet oxygen production and decay
The effect of humic acid (HA) aggregate formation on the photosensitized generation and subsequent quenching of singlet molecular oxygen O2(a1Δg) was investigated. Time-resolved O2(a1Δg) phosphorescence traces were obtained from (a) bulk samples of HA dispersions and (b) microscope-based experiments...
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| Autores principales: | , , , |
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| Formato: | Articulo |
| Lenguaje: | Inglés |
| Publicado: |
2011
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| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/139228 |
| Aporte de: |
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I19-R120-10915-139228 |
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| record_format |
dspace |
| institution |
Universidad Nacional de La Plata |
| institution_str |
I-19 |
| repository_str |
R-120 |
| collection |
SEDICI (UNLP) |
| language |
Inglés |
| topic |
Química Ciencias Exactas humic acid singlet molecular oxygen hydrophobic meso-tetraphenylporphyrin phosphorescence |
| spellingShingle |
Química Ciencias Exactas humic acid singlet molecular oxygen hydrophobic meso-tetraphenylporphyrin phosphorescence Carlos, Luciano Pedersen, Brian W. Ogilby, Peter R. Mártire, Daniel Osvaldo The role of humic acid aggregation on the kinetics of photosensitized singlet oxygen production and decay |
| topic_facet |
Química Ciencias Exactas humic acid singlet molecular oxygen hydrophobic meso-tetraphenylporphyrin phosphorescence |
| description |
The effect of humic acid (HA) aggregate formation on the photosensitized generation and subsequent quenching of singlet molecular oxygen O2(a1Δg) was investigated. Time-resolved O2(a1Δg) phosphorescence traces were obtained from (a) bulk samples of HA dispersions and (b) microscope-based experiments performed upon irradiation of a single HA aggregate. In the bulk experiments, the dependence of the O2(a1Δg) lifetime on the HA concentration yields a critical concentration for the formation of micrometric HA aggregates of 0.58 g L−1. This value is consistent with that obtained using pyrene as a fluorescent probe (0.38 g L−1). Microscope-based experiments were also performed with HA samples containing added singlet oxygen sensitizers; either the hydrophobic meso-tetraphenylporphyrin (TPP) or the hydrophilic 5,10,15,20-tetrakis(N-methyl-4-pyridyl)-21H,23H-porphine (TMPyP). Singlet oxygen phosphorescence could only be detected upon irradiation of TMPyP, a molecule which localizes on the exterior part of the HA aggregates. The inability to detect O2(a1Δg) phosphorescence from HA samples containing TPP is consistent with the model that the O2(a1Δg) produced in the interior of the aggregate was completely quenched by the high local concentration of HA reactive groups in this environment. |
| format |
Articulo Articulo |
| author |
Carlos, Luciano Pedersen, Brian W. Ogilby, Peter R. Mártire, Daniel Osvaldo |
| author_facet |
Carlos, Luciano Pedersen, Brian W. Ogilby, Peter R. Mártire, Daniel Osvaldo |
| author_sort |
Carlos, Luciano |
| title |
The role of humic acid aggregation on the kinetics of photosensitized singlet oxygen production and decay |
| title_short |
The role of humic acid aggregation on the kinetics of photosensitized singlet oxygen production and decay |
| title_full |
The role of humic acid aggregation on the kinetics of photosensitized singlet oxygen production and decay |
| title_fullStr |
The role of humic acid aggregation on the kinetics of photosensitized singlet oxygen production and decay |
| title_full_unstemmed |
The role of humic acid aggregation on the kinetics of photosensitized singlet oxygen production and decay |
| title_sort |
role of humic acid aggregation on the kinetics of photosensitized singlet oxygen production and decay |
| publishDate |
2011 |
| url |
http://sedici.unlp.edu.ar/handle/10915/139228 |
| work_keys_str_mv |
AT carlosluciano theroleofhumicacidaggregationonthekineticsofphotosensitizedsingletoxygenproductionanddecay AT pedersenbrianw theroleofhumicacidaggregationonthekineticsofphotosensitizedsingletoxygenproductionanddecay AT ogilbypeterr theroleofhumicacidaggregationonthekineticsofphotosensitizedsingletoxygenproductionanddecay AT martiredanielosvaldo theroleofhumicacidaggregationonthekineticsofphotosensitizedsingletoxygenproductionanddecay AT carlosluciano roleofhumicacidaggregationonthekineticsofphotosensitizedsingletoxygenproductionanddecay AT pedersenbrianw roleofhumicacidaggregationonthekineticsofphotosensitizedsingletoxygenproductionanddecay AT ogilbypeterr roleofhumicacidaggregationonthekineticsofphotosensitizedsingletoxygenproductionanddecay AT martiredanielosvaldo roleofhumicacidaggregationonthekineticsofphotosensitizedsingletoxygenproductionanddecay |
| bdutipo_str |
Repositorios |
| _version_ |
1764820457291251712 |