The mechanical properties of Pt monatomic chains were investigated by a simultaneous measurement of effective stiffness and conductance using our recently developed mechanically controllable break junction technique with a tuning fork as a force sensor. When stretching a monatomic contact ͑two-atom chain͒, the stiffness and conductance increases at the early stage of stretching and then decreases just before breaking, which is attributed to a transition of the chain configuration and bond weakening. A statistical analysis was made to investigate the mechanical properties of monatomic chains. The average stiffness shows minima at the peak positions of the length histogram. From this result, we conclude that the peaks in the length histogram are a measure of the number of atoms in the chains and that the chains break from a strained state. Additionally, we find that the smaller the initial stiffness of the chain is, the longer the chain becomes. This shows that softer chains can be stretched longer.
We present a review of literature on aspects of sound production in a clarinet which involve non-linearities of the flow in the instrument. We discuss the flow in the reed channel, the contribution of turbulence to the sound production, the vortex shedding at tone holes and the pipe termination and finally we discuss the non-linear wave deformation in the pipe. Most of these effects can only be described qualitatively on the basis of existing theories and the experimental data are insufficient. Further research is welcome. Bouasse dixit: J'ai appris par les afiches que la Faculte' des Sciences de Toulouse possdde un Institut de Mkcanique des jluides; est-il besoin de dire que je n'ai rien de commun avec cet institut, pas davantuge avec E'lnstitut Electrotechnique oG cette mkcanique est e'gulement en honneur. Je pre'viens le lecteur pour qu'il ne soit pas surpris des contradictions entre ce que je signe et ce qu'e'labore ces messieurs.[l]. 'In which the listener is immerged.
We have developed a sensor to study the mechanical stiffness of atomic-size contacts. It consists of a modification of the mechanically controllable break-junction technique, using a quartz tuning fork resonator as force sensor. We present first results of measurements of the force constants in gold atomic contacts. In the formation of chains of single-metal atoms, the folding in of individual atoms from the banks into the chain can be observed. This sensor allows one to measure forces in atomic contacts for a wide variety of metals, as illustrated with the first measurements on platinum.
Currently, three MAPPER multi-electron beam lithography tools are operational. Two are located at customers, TSMC and LETI, and one is located at MAPPER. The tools at TSMC and LETI are used for process development. These tools each have 110 parallel electron beams and have demonstrated sub-30 nm half pitch resolution in chemically amplified resists [5].One important step towards the high volume tool is the capability to stitch the exposure of one electron beam to the next. The pre-alpha tool at MAPPER has been upgraded with an interferometer to enable exposures with a scanning stage and demonstrate first beam-to-beam stitching. A scan of 200 micrometers has been used to create a stitch area of 50 x 3 microns. The stitch error over all stitches was found to be below 25 nm.The electron beam position stability during the 10 seconds required for beam-to-beam stitching showed a contribution to the stitch error of 2.3 nm. The beam separation measurement, used to correct the static error, adds about 2.2 nm and the stage stability and linearity adds another 5 nm in the scan (interferometer) direction. In the perpendicular direction the stage instability gives the largest contribution to the stitch error (15 nm) due to the use of capacitive sensors.Overall, the electron beam stability and the beam position correction method work correctly and with sufficient accuracy for the high volume tool, 'Matrix'. The wafer stage for the Matrix system will incorporate full interferometer control to attain the needed positioning accuracy and stability.
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