Metal nanoparticle-enhanced radiative transitions: Giving singlet oxygen emission a boost

• The fabrication and use of metal nanoparticles to influence electronic transitions in a given molecule is of growing interest; there is much to be gained by developing and exploiting methods to enhance weak optical signals. Singlet molecular oxygen, O-2(a(1)Delta(g)), which is an important intermediate in many oxidation reactions, particularly in biological systems, is ideally monitored by the 1275-nm O-2(a(1)Delta(g)) -> O-2(X-3 Sigma(-)(g)) phosphorescent transition. Unfortunately, the latter is highly forbidden and, as such, often presents a severe limitation in the application of this optical probe. In this paper, we describe how this weak phosphorescent transition can be enhanced by using localized surface plasmons (LSPs) from specially engineered gold nanostructures. In an attempt to elucidate the mechanism of this process, data were recorded from samples in which we decoupled the component of the plasmon resonance that absorbs incident light from the component that scatters incident light. We find that the latter appears to be the feature of significance in the process through which singlet oxygen phosphorescence is enhanced. In this work, we also illustrate how the singlet oxygen system provides an ideal model for a general study of metal-enhanced radiative rate constants.

Subject headings

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Keyword

radiative transition

metal-enhanced fluorescence

nanorods

phosphorescence

fluorescence intensity

colloidal lithography

singlet oxygen

plasmon resonances

gold nanoparticles

nanostructures

gold nanoparticles

optical-properties

surface plasmon

solvent

surface

Publication and Content Type

art (subject category)

ref (subject category)