A new method that fits the whole temperature response of a heat-pulse calorimeter for heat capacity is developed. Analyzing the thermal response of a heat-pulse calorimeter on a model that was used by the relaxation method, the authors derived some useful relations and further utilized the numeric method of the general linear least squares to determine the heat capacity of a sample. Absolute accuracy of the proposed method was verified by determining the heat capacity of a 0.249 76 g copper sample (purity 99.999%) on a self-designed and fully automated calorimetric system from 4.5 to 80 K. Comparing the result with the literature, the deviation in average was 1.2% from 4.5 to 20 K and 2.0% from 20 to 80 K. It is found that the proposed method is capable of measuring heat capacity regardless if the sample is adiabatically or nonadiabatically isolated. The size of the specimen is not critical for the application of the method and the temperature range of measurement can be expanded. It also deals with the τ2 effect. Details of the employed calorimetric system are described. Stability, inherent limitations, and further improvement of the system are also discussed.

We report the use of a compact continuous-wave sub-terahertz system for inspection applications, using electronic generation and detection methods. A combination of a Gunn diode emitter, a Schottky diode detector, and a polyethylene Fresnel lens provides line-scan images at 0.2 m / s with a data acquisition rate of 512 points/ s. Examples of the measurement of NASA's insulating panels and applicability of the technology to other nondestructive testing applications are presented and discussed.

We report an evaluation of pulsed terahertz (THz) time-domain measurement and continuous wave (CW) terahertz measurement for non-destructive testing applications. The strengths and limitations of the modalities are explored via the example of the detection of defects in space shuttle foam insulation. It is decided that CW imaging allows for a more compact and simple system, while pulsed measurements yield a broader range of information.

Quantitative mapping of layer number and stacking order for CVD-grown graphene layers is realized by formulating Raman fingerprints obtained on two stepwise stacked graphene single-crystal domains with AB Bernal and turbostratic stacking (with ~30°interlayer rotation), respectively. The integrated peak area ratio of the G band to the Si band, A(G)/A(Si), is proven to be a good fingerprint for layer number determination, while the area ratio of the 2D and G bands, A(2D)/A(G), is shown to differentiate effectively between the two different stacking orders. The two fingerprints are well formulated and resolve, quantitatively, the layer number and stacking type of various graphene domains that used to rely on tedious transmission electron microscopy for structural analysis. The approach is also noticeable in easy discrimination of the turbostratic graphene region (~30° rotation), the structure of which resembles the well known high-mobility graphene R30/R2(±) fault pairs found on the vacuum-annealed C-face SiC and suggests an electron mobility reaching 14,700 cm(3) V(-1) s(-1). The methodology may shed light on monitoring and control of high-quality graphene growth, and thereby facilitate future mass production of potential high-speed graphene applications.

One of the key challenges in artificial photosynthesis is to design a photocatalyst that can bind and activate the CO molecule with the smallest possible activation energy and produce selective hydrocarbon products. In this contribution, a combined experimental and computational study on Ni-nanocluster loaded black TiO (Ni/TiO ) with built-in dual active sites for selective photocatalytic CO conversion is reported. The findings reveal that the synergistic effects of deliberately induced Ni nanoclusters and oxygen vacancies provide (1) energetically stable CO binding sites with the lowest activation energy (0.08 eV), (2) highly reactive sites, (3) a fast electron transfer pathway, and (4) enhanced light harvesting by lowering the bandgap. The Ni/TiO photocatalyst has demonstrated highly selective and enhanced photocatalytic activity of more than 18 times higher solar fuel production than the commercial TiO (P-25). An insight into the mechanisms of interfacial charge transfer and product formation is explored.