The complex refractive indices of polymers have important applications in the analysis of their components and the study of radiation endothermic mechanisms. Since these materials have high transmittance in the visible to near-infrared ranges, it is difficult to accurately measure their complex refractive indices. At present, the data for complex refractive indices of polymers are seriously lacking, which greatly limits the applications of these materials in the field of thermal radiation. In this work, spectroscopic ellipsometry (SE) combined with the ray tracing method (RTM) is used to measure the complex refractive indices of five polymers, polydimethylsiloxane, poly(methyl methacrylate) (PMMA), polycarbonate, polystyrene, and polyethylene terephthalate, in the spectral range of 0.4–2 µm. The double optical pathlength transmission method (DOPTM) is used to measure the complex refractive indices of three polymers, PMMA, polyvinyl chloride, and polyetherimide, in the 0.4–2 µm range. The complex refractive index of PMMA measured by the DOPTM almost coincides with the data measured by SE combined with the RTM. The results show that the trends of the complex refractive indices spectra for the seven polymers in the 0.4–2 µm range are similar. This work makes up for the lack of complex refractive indices in the 0.4–2 µm range for these seven materials and points out the direction for accurate measurements of the complex refractive indices of polymers with weak absorption.

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Low-temperature CO oxidation is among the most interesting reactions in heterogeneous catalysis. It is well known that this reaction can be catalyzed by gold deposited as nanoparticles on metal oxide surfaces (e.g. TiO 2 , MgO, and ZnO). [1] Developing highly efficient and low-cost catalysts for low-temperature CO oxidation represents a major challenge. Most recently, Cubased metal-organic frameworks (MOFs) have been identified for efficient CO oxidation at ambient pressure and elevated temperatures, namely [Cu 3 btc 2 ] (btc= benzene-1,3,5-tricarboxylate ) and [Cu 5 (OH) 2 (nip) 4 (H 2 O) 6 ] (H 2 O) 4.25 (nip = 5-nitroisophthalate) with 100 % conversion at 240 8C and 200 8C, respectively. [2,3] However, the origin of the catalytic activity of such Cu-MOFs is not well understood.Coordinatively unsaturated metal ion sites (CUS) at the backbone of MOFs [4] are known to play an important role for catalysis, [5] gas storage, [6] chemical sensing, [7] and other applications. For catalysis, Schlichte et al. [8] reported on the cyanosilylation of benzaldehyde and acetone with [Cu 3 btc 2 ] as catalyst (HKUST-1, [9] Figure S1) for which its activity was assigned to the Lewis acid properties of intrinsic Cu 2 + CUS at the copper-carboxylate paddle-wheel building unit (CuPW) of this prototypical MOF in its dehydrated form. The characterization of reactive CUS of MOFs with infrared spectroscopic techniques and suitable probe molecules, quite similar to classic heterogeneous catalysts, [10] is expected to provide most valuable information for mechanistic understanding and fine tuning of the MOF materials.Herein, we present our studies on the in situ monitoring of the co-adsorption of CO and O 2 at [Cu 3 btc 2 ] (HKUST-1) [9] and its congener [Cu 3 btb 2 ] (MOF-14, [11] btb = benzene-1,3,5-tribenzoate) by using an ultrahigh vacuum infrared spectroscopy tool (UHV-FTIRS). [12] The high-quality IR data provide unambiguous spectroscopic evidence for the surprisingly high catalytic activity of both Cu-MOFs samples for CO oxidation at temperatures as low as 105 K, according to Scheme 1.

Fourier transform infrared (FTIR) spectroscopy is one of the widely used vibrational spectroscopic methods in protein structural analysis. The protein solution sample loaded in demountable CaF liquid cell presents a challenge and is limited to high concentrations. Some researchers attempted the simpler solid-film sampling method for the collection of protein FTIR spectra. In this study, the solid-film sampling FTIR method was studied in detail. The secondary structure components of some globular proteins were determined by this sampling method, and the results were consistent with those data determined by the traditional solution sampling FTIR method and X-ray crystallography, indicating that this sampling method is feasible and efficient for the structural characterization of proteins. Furthermore, much lower protein concentrations (~0.5 mg/mL) were needed to obtain high-quality FTIR spectra, which expands the application of FTIR spectroscopy to almost the same concentration range used for circular dichroism and fluorescence spectroscopy, making comparisons among three commonly used techniques possible in protein studies. Graphical Abstract ᅟ.

A X-band variable gain amplifier (VGA) with low phase variation and high control resolution is presented in 180-nm CMOS. The linear gain VGA and current-type digital-toanalog converter (DAC) are implemented to improve the accuracy of gain control and the robustness against process, supply voltage, and temperature variations (PVT). The measured peak gain and 3-dB bandwidth are 8 dB and 8.5 to 11.6 GHz, respectively. The gain range is 15 dB with a gain step of 1 dB. With a supply voltage varying from 1.6 to 2.0 V, the root-mean-square (RMS) gain and phase errors in 3-dB bandwidth are <0.62 dB and <1.5 , respectively. With supply of 1.8 V, the measured root-meansquare (RMS) gain and phase errors across −25 to 110 C are <0.65 dB and <1.7 , respectively. Comparing the measurement results of five chips, the variation of RMS gain error is <0.24 dB, and the RMS phase errors are almost the same. The measurement results demonstrate the proposed VGA is very suitable for phased arrays in X-band.