An approach was developed to determine triplet quantum yields, ΦT, which overcomes most of the difficulties usually encountered in flash photolysis studies of triplet states. The combined application of near-IR emission and optoacoustics yields ΦT values which are independent of the absorption properties of the triplets. Thus, the triplet energies derived from near-IR phosphorescence spectra together with the values of the heat stored by the triplets determined from optoacoustic experiments afforded ΦT = 0.3 ± 0.1 for porphycene (PO) and 0.4 ± 0.1 for its tetra-n-propyl derivative (TPrPO). Several calorimetric references for optoacoustic measurements in the red region were tested. The ΦT values, combined with flash photolysis data, yielded accurate triplet- minus ground-state absorption coefficients. The quantum yields for singlet molecular oxygen production determined by time-resolved phosphorescence were ΦΔ = 0.34 ± 0.05 for PO and 0.36 ± 0.03 for TPrPO which implies an efficiency near unity for O2(1Δ8) production upon collision of the triplet states of the porphycenes with ground-state O2. © 1990 American Chemical Society.
Documento: | Artículo |
Título: | Laser-induced optoacoustics combined with near-infrared emission. An alternative approach for the determination of intersystem crossing quantum yields applied to porphycenes |
Autor: | Nonell, S.; Aramendía, P.F.; Heihoff, K.; Negri, R.M.; Braslavsky, S.E. |
Filiación: | Max-Planck-Institut für Strahlenchemie, D-4330 Mülheim a.d. Ruhr, Germany Facultad de Ciencias Exactas y Naturales, Departamento de Química Inorgánica, Universidad de Buenos Aires, 1428 Buenos Aires, Argentina |
Año: | 1990 |
Volumen: | 94 |
Número: | 15 |
Página de inicio: | 5879 |
Página de fin: | 5883 |
DOI: | http://dx.doi.org/10.1021/j100378a051 |
Título revista: | Journal of Physical Chemistry |
ISSN: | 00223654 |
PDF: | https://bibliotecadigital.exactas.uba.ar/download/paper/paper_00223654_v94_n15_p5879_Nonell.pdf |
Registro: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00223654_v94_n15_p5879_Nonell |