We shine light on the covalent modification of graphite and graphene substrates using diazonium chemistry under ambient conditions. We report on the nature of the chemical modification of these graphitic substrates, the relation between molecular structure and film morphology, and the impact of the covalent modification on the properties of the substrates, as revealed by local microscopy and spectroscopy techniques and electrochemistry. By careful selection of the reagents and optimizing reaction conditions, a high density of covalently grafted molecules is obtained, a result that is demonstrated in an unprecedented way by scanning tunneling microscopy (STM) under ambient conditions. With nanomanipulation, i.e., nanoshaving using STM, surface structuring and functionalization at the nanoscale is achieved. This manipulation leads to the removal of the covalently anchored molecules, regenerating pristine sp(2) hybridized graphene or graphite patches, as proven by space-resolved Raman microscopy and molecular self-assembly studies.

This is the first report of impedance technique run on single particle LiCoO 2 electrodes with the aim of clarifying its electronic and ionic transport properties. Measurements were successfully conducted on a LiCoO 2 particle of 15 m diam resulting in impedance magnitude on the order of M⍀. The impedance spectra exhibited ͑i͒ one semicircle in the high frequency region, ͑ii͒ Warburg impedance in low frequencies, and finally, ͑iii͒ a limiting capacitance in the very low frequencies. The spectra were analyzed using a modified Randles-Ershler circuit, so that the reaction kinetics could be precisely evaluated. The charge transfer resistance decreased as the potential increased, whereas the double layer capacitance was almost invariant with the potential. Thus, the apparent chemical diffusion coefficient (D app ) of lithium ions was determined to be 10 Ϫ11 to 10 Ϫ7 cm 2 /s as function of electrode potential. These results are in agreement with those obtained by potential step chronoamperometry technique.

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A Pt(II) complex, bearing an oligo-ethyleneoxide pendant, is able to selfassemble in ultralong ribbons that display mechanochromism upon nanoscale mechanical stimuli, delivered through atomic force microscopy (AFM). Such observation paves the way to fine understanding and manipulation of the mechanochromic properties of such material at the nanoscale. AFM allows quantitative assessment of nanoscale mechanochromism as arising from static pressure (piezochromism) and from shear-based mechanical stimuli (tribochromism), and to compare them with bulk pressure-dependent luminescence observed with diamond-anvil cell (DAC) technique. Confocal spectral imaging reveals that mechanochromism only takes place within short distance from the localized mechanical stimulation, which allows to design high-density information writing with AFM nanolithography applied on individual self-assembled ribbons. Each ribbon hence serves as an individual microsystem for data storage. The orange luminescence of written information displays high contrast compared to cyan native luminescence; moreover, it can be selectively excited with visible light. In addition, ribbons show photochromism, i.e., the emission spectrum changes upon exposure to light, in a similar way as upon mechanical stress. Photochromism is here conveniently used to conceal and eventually erase information previously written with nanolithography by irradiation.

Although adverse health effects of carbon black (CB) exposure are generally accepted, a direct, label-free approach for detecting CB particles in fluids and at the cellular level is still lacking. Here, we report nonincandescence related white-light (WL) generation by dry and suspended carbon black particles under illumination with femtosecond (fs) pulsed near-infrared light as a powerful tool for the detection of these carbonaceous materials. This observation is done for four different CB species with diameters ranging from 13 to 500 nm, suggesting this WL emission under fs near-infrared illumination is a general property of CB particles. As the emitted radiation spreads over the whole visible spectrum, detection is straightforward and flexible. The unique property of the described WL emission allows optical detection and unequivocal localization of CB particles in fluids and in cellular environments while simultaneously colocalizing different cellular components using various specific fluorophores as shown here using human lung fibroblasts. The experiments are performed on a typical multiphoton laser-scanning microscopy platform, widely available in research laboratories.