STM-induced light emission from thin films of perylene derivatives on the HOPG and Au substrates
- PDF / 653,097 Bytes
- 8 Pages / 595.28 x 793.7 pts Page_size
- 43 Downloads / 162 Views
NANO EXPRESS
Open Access
STM-induced light emission from thin films of perylene derivatives on the HOPG and Au substrates Aya Fujiki1*, Yusuke Miyake1, Yasushi Oshikane1, Megumi Akai-Kasaya1, Akira Saito1,2 and Yuji Kuwahara1
Abstract We have investigated the emission properties of N,N’-diheptyl-3,4,9,10-perylenetetracarboxylic diimide thin films by the tunneling-electron-induced light emission technique. A fluorescence peak with vibronic progressions with large Stokes shifts was observed on both highly ordered pyrolytic graphite (HOPG) and Au substrates, indicating that the emission was derived from the isolated-molecule-like film condition with sufficient π-π interaction of the perylene rings of perylenetetracarboxylic diimide molecules. The upconversion emission mechanism of the tunnelingelectron-induced emission was discussed in terms of inelastic tunneling including multiexcitation processes. The wavelength-selective enhanced emission due to a localized tip-induced surface plasmon on the Au substrate was also obtained. Introduction Control of molecular emission from organic materials has attracted much attention owing to its potential applications not only in basic molecular science but also in research on soft material devices such as organic light-emitting diodes (OLEDs) and biosensors [1-4]. Scanning-tunneling-microscope-induced light emission (STM-LE) spectroscopy is highly effective for characterizing the optical and electronic properties of nanoscale materials such as organic single molecules or thin films at the atomic scale. However, it involves serious analytical difficulties in receiving extremely weak signals from the objective materials. To overcome such difficulties, it is promising to combine STM-LE spectroscopy with plasmon enhancement on surfaces. Surface plasmons at the interface between metallic and dielectric media generate an intense electromagnetic field on the surface, which provides an efficient enhancement field for some optical processes such as the fluorescence/phosphorescence emission and optical absorption of organic materials on a metal surface [1]. We have first observed the fluorescence of Cu phthalocyanine under enhancement utilizing an STM-tip-induced plasmon (TIP) [5]. For * Correspondence: [email protected] 1 Department of Precision Science & Technology, Graduate school of Engineering, Osaka University, 2-1 Yamada-oka, Suita 565-0871, Japan Full list of author information is available at the end of the article
light emission from single molecules, Qiu et al. [6] reported light emission from individual Zn(II)-etioporphyrin I molecules adsorbed on Al 2 O 3 /NiAl(110), in which an oxide buffer layer is used to prevent fluorescence quenching and disturbance of pronounced plasmon emission [7-9]. They explained that the spectra were due to the de-excitation of excited anion states resulting from hot electron injection. The plasmon enhancement effect is also expected to be applied to the development of light-emitting diodes [2,10]. Recently, we have developed a hi
Data Loading...
