Magnetic field dependence of singlet oxygen generation by nanoporous silicon.

Jamaree Amonkosolpan,James John Davies,Paul A Snow,Gazi N Aliev,Daniel Wolverson

doi:10.1186/1556-276x-9-342

Jamaree Amonkosolpan, James John Davies + Show 3 more

Open Access

https://doi.org/10.1186/1556-276x-9-342

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Journal: Nanoscale Research Letters	Publication Date: Jul 9, 2014
Citations: 13	License type: cc-by

Affiliation: University of Bath

Abstract

Energy transfer from photoexcited excitons localized in silicon nanoparticles to adsorbed oxygen molecules excites them to the reactive singlet spin state. This process has been studied experimentally as a function of nanoparticle size and applied external magnetic field as a test of the accepted understanding of this process in terms of the exchange coupling between the nano-Si exciton and the adsorbed O2 molecules.

Highlights

Since the discovery that photoexcited silicon nanoparticles can act as energy donors to molecular oxygen acceptors and can thereby excite oxygen to a highly reactive singlet state [1,2,3], there has been much work on the potential exploitation of this process
It was demonstrated that the efficiency of the energy transfer process is sensitive to an externally applied magnetic field [2], and this provided key evidence for the understanding of the process as a result of exchange coupling between an exciton confined within a silicon nanoparticle and an adsorbed oxygen molecule
Four typical PL spectra at 1.5 K for a porous silicon sample exposed to a low oxygen concentration are shown in Figure 1

Summary

Introduction

Since the discovery that photoexcited silicon nanoparticles can act as energy donors to molecular oxygen acceptors and can thereby excite oxygen to a highly reactive singlet state [1,2,3], there has been much work on the potential exploitation of this process. It was demonstrated that the efficiency of the energy transfer process is sensitive to an externally applied magnetic field [2] (the energy transfer efficiency may be monitored by its quenching of the nano-Si residual photoluminescence), and this provided key evidence for the understanding of the process as a result of exchange coupling between an exciton confined within a silicon nanoparticle and an adsorbed oxygen molecule (the Dexter exchange mechanism). The silicon photoluminescence intensity is restored towards the intensity observed when oxygen is not present

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