Metrology at nanoscale: thermal wave probe made it simple

A major hurdle facing nanotechnology implementation is in how samples of nano-scale dimensions can be probed. Parts of the problems include sample mounting, making contact with the sample; the possibility that the act of measuring alters the sample, repeatability and accuracy of measurement and referencing reference metrology to calibrate various tools to perform required measurements. The present attempted solution is certainly not a one-size-fits-all matter and no more than a complement to existing tools available such as SEM, TEM, AFM etc, which are no match for the simplicity of the thermal wave probe. Initially the thermal wave probe was not intended for nano-scale applications. The discovery of the converging thermal wave mechanism in thin subsurface layers opened up avenues for stand alone thin layer probing even for materials of high thermal conductivity and diffusivity like copper and silver. This came in tandem with the advent of nano-materials whereby electronic packaging materials could include thin layers with thermal diffusivity exceeding that of copper to alleviate problems associated with overheating. From the time the converging thermal wave technique was introduced in the mid eighties until very recently, it could only be performed with the availability of massive and expensive ultra-short lasers even though the thinnest material that could be measured was 30 μm. With the birth of the CTWaveProbeTM this myth should no longer exist. Within the limitations of standard samples available the CTWaveProbeTM has measured samples of thickness as low as 0.75 μm. In the near future everyone can perform nano-scale measurement like everyone now can fly

The reliability of optical fiber-TWRC technique in liquids thermal diffusivity measurement

The conventional thermal-wave resonator cavity (TWRC) technique was modified by using an optical fiber as both to transmit light beam and to produce thermal wave. This technique also known shortly as OF-TWRC was used to measure liquid thermal diffusivity in a thermally thick condition. The stability of the pyroelectric signal amplitude was good over long time duration. The thermal diffusivity values of various liquids obtained by this technique are in agreement with those of literature indicating this technique is reliable as compared to the conventional TWRC technique

Pencirian resonan plasmon permukaan dan penggunaan saput tipis emas sebagai lapisan aktif sensor optik

The characterizations of a surface plasmon resonance (SPR) of gold thin film at various film thickness are discussed. The measurements have been carried out for film thickness from 50.98 nm to 92.38 nm and the suitable thickness of gold film for SPR optical sensor was found as ≈ 50 nm which produces minimum reflectivity and sharp resonance. The potential application of the SPR as an optical sensor has been explored in measuring small percentage of ethanol in distilled water. The calibration curve was linear with the sensitivity recorded as 9 3 10.2/ (%vol. ethanol) for the concentration of ethanol in water 15%

Numerical solution of transient temperature for pulsed heating in a single spherical particle model

The transient temperature for pulsed heating in a single spherical model has been derived using the Laplace transform algorithm based on Fourier series. We assumed that the substrate is a thermally bad conducting surface and then head conduction at the interface can be neglected. The computation for the transient surface temperature of the particle was performed in such a way as to obtain a straightforward deviation of the analytical solution (12) from the numerical result. It has been proved that for some particles (α < 0.005) the analytical solution provided a reasonably accurate description of the model, otherwise the numerical solution should be used in the general case

Measurement of the thermal diffusivity of materials by diverging thermal wave technique

The applications of diverging thermal wave technique to measure thermal diffusivities of materials are reported. In essence, the technique makes use of the information content of the thermal waves observed by means of a wide band infrared detector, that laterally displaced from the heat source, following pulsed laser excitation of the materials. Some observations obtained from aluminium, lead, graphite foil, and zirconium graphite samples are presented

The use of a laser light-scattering technique in fluvial sediment measurement

In this paper, we report the measurement of sediment concentration using a laser light-scattering technique. In its present form, the technique suffers from several practical limitations but these are outweighed by the simplicity and speed of the technique. The procedures used in overcoming the accompanying problems are discussed