Since its first experimental realization, tip-enhanced Raman spectroscopy (TERS) has emerged as a potentially powerful nanochemical analysis tool. However, questions about the comparability and reproducibility of TERS data have emerged. This interlaboratory comparison study addresses these issues by bringing together different TERS groups to perform TERS measurements on nominally identical samples. Based on the spectra obtained, the absolute and relative peak positions, number of bands, peak intensity ratios, and comparability to reference Raman and surface-enhanced Raman spectroscopy (SERS) data are discussed. Our general findings are that all research groups obtained similar spectral patterns, irrespective of the setup or tip that was used. The TERS (and SERS) spectra consistently showed fewer bands than the conventional Raman spectrum. When comparing these three methods, the spectral pattern match and substance identification is readily possible. Absolute and relative peak positions of the three major signals of thiophenol scattered by 19 and 9 cm À1 , respectively, which can probably be attributed to different spectrometer calibrations. However, within the same group (but between different tips), the signals only scattered by 3 cm À1 on average. This study demonstrated the suitability of TERS as an analytical tool and brings TERS a big step forward to becoming a routine technique.

Electric field-induced modulation of the near-field photoluminescence of thin films of the conjugated polymer MEH-PPV was measured. A voltage bias applied between the near-field probe and the substrate results in a highly spatially confined electric field. The near-field photoluminescence intensity decreases when the sample bias is positive with respect to the probe while the intensity increases when the sample bias is negative. The modulation of photoluminescence intensity provides a sensitive measure of changes in the local carrier density induced by the applied electric field. Experiments performed with a blocking layer indicate that carriers are generated by photoexcitation in the bulk of the polymer film. On the basis of the modulation results, we estimate the concentration of holes under optical and electrical excitation to be 10 17 cm -3 . The temporal response of the fluorescence upon the application of voltage is described in terms of the carrier mobility and electric field.

We present a study of the dynamic behavior of tuning forks and the application of tuning fork based shear force microscopy on soft samples in liquid. A shift in resonance frequency and a recovery of the tip vibration amplitude have been observed upon immersion into liquid. Conservation of the vibration mode is confirmed by both direct stroboscopic observation and by detection of the tip vibration amplitude of the tuning fork. Thanks to the partial recovery of the Q factor upon complete immersion into liquid, it is possible to obtain high-resolution images on soft samples in liquid. This opens a new domain of applications for tuning fork based near-field scanning optical microscopes.

The formation and observation, with reflected light, of 60-nm-diam phase-changed domains in a thin GeSbTe film using a scanning near-field optical microscope with a 785 nm wavelength laser diode is demonstrated. The dependence of the domain size on incident laser power was obtained, and the size changed from 150 to 60 nm in diameter with incident power of 8.4–7.3 mW in the probe. At the threshold power of 7.3 mW, the film temperature rose to around 180 °C to partially phase change the local area of the film from amorphous to crystalline. A detected reflectivity increase due to phase change in the formed domain was 8%–2%. The observing (reading) was performed with an incident laser power of 0.2 mW, which corresponds to 10−2–10−3 times less than in a magneto-optical recording. The incident laser power shows that the phase change reading using the reflection scanning near-field optical microscope has the potential to read the recorded bit at a speed over 10 MHz.

Homoleptic NiII and FeII complexes of the “large‐surface” phenanthroline‐type ligand 1,12‐diazaperylene (dap), [Ni(dap)3](BF4)2 (1) and [Fe(dap)3](PF6)2 (2), respectively, were synthesized. In the crystal structure the complex cation [M(dap)3]2+ (M = Ni, Fe) exhibits C3 symmetry and interacts with three other cations by π‐π stacking. It forms a new metalla‐supramolecular assembly with a honeycomb structure containing nanochannels running parallel to the crystallographic c axis. Aggregation by π‐π stacking between metal complexes of “large‐surface” ligands should give new perspectives for inorganic supramolecular chemistry. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

We present for the first time a nanometer-sized phase-change recording using a scanning near-field optical microscope (PC-SNOM recording). The recording experiments were performed with a SNOM using a 785-nm-wavelength semiconductor laser diode, shear force detection for gap control and reflected light detection for observing the domains (reading). The recording media of ZnS·SiO2(20 nm)/GeSbTe(30 nm)/ZnS·SiO2(150 nm)/polycarbonate substrate were used. The writings were done at laser powers of 8.4–7.3 mW in the probe for pulse widths of 5 or 0.5 ms. As a result, we obtained a minimum recorded domain size of 60 nm in diameter. This size shows a potential to achieve an ultrahigh density PC-SNOM recording with about 170 Gb/in2. A possibility of achieving high speed readout for the future data storage is also discussed.

No abstract

The complex formation of the ligands 1,12-diazaperylene (dap), 1,1'-bisisoquinoline (bis), 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen) with transition metal ions (M = Fe, Co, Ni, Cu, Zn, Ru, Os, Re, Pd, Pt, Ag and Cd) in the gas phase has been studied by electrospray ionization mass spectrometry. With the exception of Ru, Os, Fe, Ni and Cu, singly charged complexes [MLn](+) (n = 1,2) were observed. The complexes of dap and bis with Ru, Os, Fe and Ni ions, and the mixed ligand complexes with bpy and phen, are preferably of the doubly charged type [ML3]2+. In addition, collision-induced dissociation (CID) measurements were employed to evaluate the relative stabilities of these complexes. The CID experiments of mixed-ligand complexes which contain both dap and phen or dap and bpy exhibit preferential elimination of bpy, indicating that bpy is a weaker ligand than phen and dap.