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Carbon nanotubes (CNTs) are attractive nanodevice components due to their unique electronic structure, molecular dimensions, and shape.[1] The remarkable structural integrity of CNTs [2] and progress in techniques to assemble them into mesoarchitectures [3] make them attractive templates to assemble other low-dimensional structures (e.g., nanoparticles, biomolecules) to create hybrid nano-and mesostructures, composites, [4] and devices. Hybrid structures allow access to new electronic, electrical, and magnetic properties and provide additional degrees of freedom that enable the assembly and interconnection of nanostructures into architectures for nanodevice fabrication. For example, CNTs derivatized with Au [5] or Co [6] nanoparticles exhibit single-electron transport or enhanced spin polarization, respectively, which could be harnessed for nanoelectronics and spintronics. Molecular-recognition-based self-assembly of DNA-modified CNTs has also been demonstrated for fabricating test devices. [7,8] However, lack of control over the functionalization location in the CNTs remains a major challenge for realizing hybrid mesoarchitectures, e.g., with molecularly networked CNTs, or CNTs decorated with nanoparticles or biomolecules at preselected locations. Site-specific functionalization of CNTs will not only facilitate the assembly of nanoscale blocks, but will also allow addressing preselected segments of the CNTs using nanoparticles or biomolecules, thereby paving the way for new up-scalable device concepts. Creating CNT templates with specific chemically active locations is a crucial step towards achieving such possibilities.Several strategies have been devised to functionalize CNTs to harness them for applications such as CNT-filled composites, field emitters, sensors, and catalyst supports. Examples include acid-based wet-chemical oxidation, amidation, or esterification, diimide activation and solubilization of CNTs, or hydrophobic adsorption of aromatic derivatives.[9-13] These strategies typically rely on random defect creation or adsorption, and do not allow precise control over the functionalization location. For example, ultrasonication in oxidative environments generates dangling bonds at random spots on CNT sidewalls, and enables the formation of functional groups at these locations via decomposition of the reactive organic molecules used. [14] The type and location of defects, however, are difficult to control, rendering such methods unsuitable for applications where the electronic properties of CNT need to be preserved. Although hydrophobic derivatization [13] does not need defect creation, the lack of site selectivity limits its use for anchoring nanostructures to specific locations of CNTs for site-specific addressing or to utilize them as nodes for further organization and assembly.Here, we demonstrate a new approach using focused-ionbeam (FIB) irradiation and subsequent mild chemical treatments to functionalize multiwalled CNTs at preselected locations. This approach involves the use of kiloelectronvol...

ily connected to an optical fiber obtaining a FOS with a working wavelength of 1.5 lm. On the other hand, the sensing element is widely tailorable, in the sense that one could explore other DBR parameters and metal nanoparticles in order to control the selectivity of the sensing element in different wavelength domains. The underlying physical phenomenon, i.e., the diffusion of solvent molecules in a metal nanoparticle/ polymer composite layer, is indeed poorly understood and depends on several factors, such as the physical and chemical properties of the polymer and the metal nanoparticles.In conclusion, the DBR based on Teflon-like and Au nanoparticle/Teflon-like polymers is a promising sensing element, the attraction of which is essentially threefold: first, the Teflonlike polymer is characterized by important properties such as a remarkable chemical resistance, a high thermal stability, a good flame resistance, and an excellent toughness, which are added to the typical polymer advantages such as low-cost fabrication and immense tailorability; second, the DBR can be easily integrated with an optical fiber, with the possibility of tuning the operation wavelength in the optical telecommunication range; third, the sensor can operate at room temperature. All these properties make this sensor particularly suitable for commercial devices, as well as for use in hostile conditions. Vapor-Sensing Properties: The effects of the surrounding vapor on our sensing DBR were tested by reflectance measurements using a spectrophotometer arranged for experiments in the presence of gas or vapors. The samples were inserted into a glass tube through which flowed synthetic air (20.5 vol.-% O 2 in N 2 ) as carrier gas. The organic vapor was introduced by bubbling synthetic air through the organic liquid and the mixing the saturated synthetic air with the carrier gas to produce the desired concentration. The measurements were carried out at room temperature. Direction-Selective and Length-Tunable In-Plane Growth of Carbon Nanotubes** By Anyuan Cao, Rajashree Baskaran, Matthew J. Frederick, Kimberly Turner, Pulickel M. Ajayan, and Ganapathiraman Ramanath* Carbon nanotubes (CNTs) are fascinating one-dimensional molecular structures that can be either metallic or semiconducting, depending on their diameter and helicity.

Cu-alloy films are being explored for integrated circuits, for creating low-resistivity interconnects with stabilized metal/dielectric interfaces via solute segregation, and for interfacial reactions. Here, we describe the pathways of microstructure evolution in supersaturated Cu– 5–12 at. % Mg films, and phase formation at the film/SiO2 interface during annealing. The as-deposited films consist primarily of a Cu–Mg solid solution with trace amounts of orthorhombic CuMg2. Upon annealing to 400 °C, Mg segregates to the surface and the Cu–Mg grains grow from an average size of 20 to 60 nm, resulting in a ∼25%–40% decrease in film resistivity. In the same temperature regime, CuMg2 phase dissolves and fcc Cu2Mg forms. Upon annealing to higher temperatures, Mg segregates to the film/silica interface, reduces SiO2, and forms fcc MgO on the silica side of the interface. The Si released by this interfacial reaction diffuses into the metal film resulting in a ∼40%–190% increase in resistivity, for films with 8–12 at. % Mg, respectively. These results are of relevance for understanding microstructure evolution in alloy films and exploring the use of Cu alloys as interconnects in integrated circuits.

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