The ability to engineer the thermal conductivity of materials allows us to control the flow of heat and derive novel functionalities such as thermal rectification, thermal switching and thermal cloaking. While this could be achieved by making use of composites and metamaterials at bulk length-scales, engineering the thermal conductivity at micro- and nano-scale dimensions is considerably more challenging. In this work, we show that the local thermal conductivity along a single Si nanowire can be tuned to a desired value (between crystalline and amorphous limits) with high spatial resolution through selective helium ion irradiation with a well-controlled dose. The underlying mechanism is understood through molecular dynamics simulations and quantitative phonon-defect scattering rate analysis, where the behaviour of thermal conductivity with dose is attributed to the accumulation and agglomeration of scattering centres at lower doses. Beyond a threshold dose, a crystalline-amorphous transition was observed.

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Split-ring resonators are basic elements of metamaterials, which can induce a magnetic response in metallic nanosctructures. Tunability of such response up to the visible frequency range is still a challenge. Here we introduce the concept of the split-ball resonator and demonstrate the strong magnetic response in the visible for both gold and silver spherical plasmonic nanoparticles with nanometre scale cuts. We realize this concept experimentally by employing the laser-induced transfer method to produce near-perfect metallic spheres and helium ion beam milling to make cuts with the clean straight sidewalls and nanometre resolution. The magnetic resonance is observed at 600 nm in gold and at 565 nm in silver nanoparticles. This method can be applied to the structuring of arbitrary three-dimensional features on the surface of nanoscale resonators. It provides new ways for engineering hybrid resonant modes and ultra-high near-field enhancement.

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Observations of the interior structure of cells and subcellular organelles are important steps in unraveling organelle functions. Microscopy using helium ions can play a major role in both surface and subcellular imaging because it can provide subnanometer resolutions at the cell surface for slow helium ions, and fast helium ions can penetrate cells without a significant loss of resolution. Slow (e.g., 10-50 keV) helium ion beams can now be focused to subnanometer dimensions (∼0.25 nm), and keV helium ion microscopy can be used to image the surfaces of cells at high resolutions. Because of the ease of neutralizing the sample charge using a flood electron beam, surface charging effects are minimal and therefore cell surfaces can be imaged without the need for a conducting metallic coating. Fast (MeV) helium ions maintain a straight path as they pass through a cell. Along the ion trajectory, the helium ion undergoes multiple electron collisions, and for each collision a small amount of energy is lost to the scattered electron. By measuring the total energy loss of each MeV helium ion as it passes through the cell, we can construct an energy-loss image that is representative of the mass distribution of the cell. This work paves the way to use ions for whole-cell investigations at nanometer resolutions through structural, elemental (via nuclear elastic backscattering), and fluorescence (via ion induced fluorescence) imaging.

Development of the point diffraction interferometer for extreme ultraviolet lithography: Design, fabrication, and evaluation J.Masks have been identified as the high risk, high cost issue for extreme ultraviolet ͑EUV͒ lithography. Challenges in EUV mask technology such as providing a pellicle and correcting defects have prompted the search for a maskless technique. Here we describe two approaches in which the mask of a current EUV system is replaced by an array of micron-sized mirrors. Patterns are achieved by modulating individual mirrors to create selected bright and dark spots. In one approach, individual mirrors can be lowered by /4 to yield locally dark regions because of destructive interference. In another approach, each mirror is mounted on a cantilever. Selected cantilevers can be tilted such that incident light from those mirrors is out of the pupil of the imaging objective. The wafer is mechanically scanned and the object is electronically scrolled across the array of mirrors in order to build up the required pattern. We have simulated the mechanical properties of the micron-sized mirrors and some aerial images showing that sub-100 nm features appear feasible.

Pattern placement imprecision due to charging of the workpiece is believed to be a significant contribution to the total positional error in electron beam lithography. In an earlier work, Liu et al. [J. Vac. Sci. Technol. B 13, 1979 (1995)] reported that the surface potential of exposed resist could be negative or positive according to the resist thickness and the electron energy. In that work the authors were constrained to use a flood beam. In this study, we report a new independent approach using a Kelvin probe electrometer to measure the surface potential after exposure by a focused beam. There is a qualitative agreement with the earlier work in that the surface potential tends to be less positive at lower electron energies and for thicker resists. We observed positive surface potentials at 10 and 20 keV beam irradiation. This positive charging is much more evident in polybutene sulfone than in UV5.

Introduction:In March 1974, Chinese farmers made a remarkable archaeological find: during the sinking of wells for farmland irrigation construction near Xi'an (Shaanxi province, China) they discovered an army consisting of more than 8000 life-size terracotta figures of warriors and horses dating from the First Emperor of the Qin dynasty, Shi Huang Di (reigned ca 221 BC -ca 210 BC). The figures, facing east and ready for battle, were individually modelled with their own personal characteristics, and were accompanied by their weapons, real chariots, and objects of jade and bone. How, more than 2000 years ago, the ancient Chinese constructed these large and heavy statues and what technologies they used to finish such a large project are questions which are still only partially answered by modern archaeologists.The discovery that BaCuSi 2 O 6 (FitzHugh and Zycherman 1983, FitzHugh and Zycherman 1992), also known as "Chinese Purple", was the main constituent of the purple pigment used in the paint covering the warriors constitutes an enigma in itself.This pigment was also used later in the Han dynasty in pottery (hence its other common name of "Han Purple") and for trading. BaCuSi 2 O 6 is a mineral that has never been found in nature, which implies that the makers of the warriors must have been able to synthesize it. The process to synthesize BaCuSi 2 O 6 is now known to be highly complex ). An additional problem with the Egyptian-Chinese connection theory is that, to our knowledge, no Ca-bearing Egyptian Blue has been found in China. 4 In order to address these questions, we re-examined the chemistry and the morphology of purple pigments found on one of the Qin Terracotta warriors ( fig. 1). By combining our findings of the technology used in the synthesis of Chinese Purple with existing archaeological evidence, we conclude that Taoist alchemists invented this pigment as well as the related pigment Chinese Blue independently from any Egyptian influence. Experimental Methods:Our investigation was based on a two pronged approach. We used a small fraction of our specimen, ground it into fine powder and used synchrotron radiation high-resolution powder x-ray diffraction (XRD) analysis to identify the crystallographic phases present. Then based on this inventory, we used spatially resolved x-ray and electron micro-beam techniques, such as micro X-ray diffraction (µXRD), micro X-ray fluorescence (µXRF) and Scanning Electron Microscopy (SEM) based Energy Dispersive X-ray (EDX) microanalysis, to study the chemistry of individual pigment clumps and map the distribution of these and other minority phases in the pigment.These chemical and phase maps gave us an insight into how the pigment was synthesized.Synchrotron radiation is 8-12 orders of magnitude more brilliant than the high performance rotating anode x-ray tubes (Eisenberger 1986). The X-ray beams at current third generation synchrotron radiation sources can be focused to a one micrometer size spot and still maintain high photon fluxes (>10 10 ph/s/µm 2 ) to ob...