Title :

Comparison between Spontaneous and Photoinduced Ionization Mechanisms for p-Quaterphenyl in M-ZSM-5 (M = H+, Na+) Zeolites

Author(s) :

Moissette, Alain [Auteur]
Hureau, Matthieu [Auteur]
Carré, Sonia [Auteur]
Vezin, Hervé [Auteur]
Col, Perrine [Auteur]

Journal title :

The Journal of Physical Chemistry C

Abbreviated title :

J. Phys. Chem. C

Volume number :

117

Pages :

20625-20635

Publisher :

American Chemical Society (ACS)

Publication date :

2013-09-30

English keyword(s) :

Charge recombinations
Charge transfer complex
Diffuse reflectance-uv-vis
Electron transfer process
Photo-induced ionization
Reaction conditions
Spectroscopic technique
Uv-vis absorption spectroscopy
charge transfer
Electron spin resonance spectroscopy
Electron transitions
Free radical reactions
Molecules
Positive ions
Reaction kinetics
Ultraviolet spectroscopy
Zeolites
ionization

English abstract : [en]

The electron transfers following the initial ionization of a probe molecule (p-quaterphenyl) adsorbed in the channels of M-ZSM-5 (M = H+, Na+) zeolites are investigated using various complementary spectroscopic techniques. ...
Show more >The electron transfers following the initial ionization of a probe molecule (p-quaterphenyl) adsorbed in the channels of M-ZSM-5 (M = H+, Na+) zeolites are investigated using various complementary spectroscopic techniques. Under the same reaction conditions, ionization occurs spontaneously during molecule diffusion in the acid H-ZSM-5 whereas charge separation needs to be photoinduced within the pores of Na-ZSM-5. The electron transfer processes are found to be identical for both the cases in terms of transient species formed before the final charge recombination. The initial ionization leads to the formation of a radical cation which evolves gradually toward an electron/hole pair associated with a charge transfer complex. However, the reaction kinetics depend dramatically on the ionization way. As spontaneous ionization is associated with the sorption process, it is closely correlated with the molecule diffusion and, thus, is very slow due to the bulky size of the molecule. In this case, radical cations and subsequent charge transfer complexes are stabilized for months in high yield and are clearly characterized by diffuse reflectance UV-vis absorption, EPR, and Raman scattering in resonance and in off-resonance conditions. After photoionization, the evolution is followed as a function of time by using time-resolved UV-vis absorption spectroscopy on a large scale of time extending from a few microseconds to several days.Show less >

Audience :

Non spécifiée

Administrative institution(s) :

Université de Lille
CNRS

Collections :

• Laboratoire Avancé de Spectroscopie pour les Intéractions la Réactivité et l'Environnement (LASIRE) - UMR 8516

Submission date :

2021-06-17T15:20:08Z
2021-10-01T10:23:55Z