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La fotodinámica primaria del nitrato acuoso: la formación de peroxinitrito
Dorte Madsen1, Jane Larsen, Svend Knak Jensen
1Department of Chemistry, University of Aarhus, Langelandsgade 140, DK-8000, Aarhus, Denmark.
Journal of the American Chemical Society
|December 11, 2003
Resumen
Las reacciones fotoquímicas de iones de nitrato acuoso (NO3-) a 200 nm producen principalmente cis-peroxinitrito. Algunos iones de nitrato excitados vuelven al estado fundamental, mientras que una pequeña fracción se disocia en NO y O2.
Área de la Ciencia:
- La fotoquímica es la fotoquímica.
- La cinética química es la cinética química.
- La espectroscopia es una técnica de espectroscopia.
Sus antecedentes:
- El ion nitrato acuoso (NO3-) es un componente importante en varios sistemas ambientales y biológicos.
- Comprender su comportamiento fotoquímico es crucial para evaluar su destino e impacto.
Objetivo del estudio:
- Investigar las reacciones fotoquímicas primarias del ion nitrato acuoso tras la irradiación UV a 200 nm.
- Para caracterizar las especies transitorias y las vías de reacción involucradas en la fotólisis del nitrato.
Principales métodos:
- Se empleó la espectroscopia de absorción transitoria de femtosegundos para sondear reacciones en el rango de 194-388 nm.
- Las mediciones de alta resolución temporal permitieron la caracterización de fotoproductos de corta vida.
Principales resultados:
- El fotoproducto dominante es el cis-isómero de la peroxinitrita (48%).
- Una fracción significativa (44%) de los iones nitrato excitados se relajan al estado fundamental dentro de 2 ps.
- Una vía menor (8%) implica la disociación en NO y O2 o especies relacionadas.
Conclusiones:
- La fotólisis primaria del nitrato acuoso a 200 nm está dominada por la formación de cis-peroxinitrito.
- La ausencia de NO2- y NO2 sugiere que su formación en estudios previos ocurre a través de reacciones secundarias, en escalas de tiempo más largas.
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