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Marksteiner, M., Divochiy, A., Sclafani, M., Haslinger, P., Ulbricht, H., Korneev, A., et al. (2009). A superconducting NbN detector for neutral nanoparticles. Nanotechnol., 20(45), 455501.
Abstract: We present a proof-of-principle study of superconducting single photon detectors (SSPD) for the detection of individual neutral molecules/nanoparticles at low energies. The new detector is applied to characterize a laser desorption source for biomolecules and allows retrieval of the arrival time distribution of a pulsed molecular beam containing the amino acid tryptophan, the polypeptide gramicidin as well as insulin, myoglobin and hemoglobin. We discuss the experimental evidence that the detector is actually sensitive to isolated neutral particles.
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Ozhegov, R. V., Smirnov, A. V., Vakhtomin, Y. B., Smirnov, K. V., Divochiy, A. V., & Goltsman, G. N. (2009). Ultrafast superconducting bolometer receivers for terahertz applications. In Proc. PIERS (867). 777 Concord Avenue, Suite 207 Cambridge, MA 02138: The Electromagnetics Academy.
Abstract: The research by the group of Moscow State Pedagogical University into the hot-electron phenomena in thin superconducting films has led to the development of new types of detectors and their use both in fundamental and applied studies. In this paper, we present the results of testing the terahertz HEB receiver systems based on ultrathin (∼ 4 nm) NbN and MoRe detectors with a response time of 50 ps and 1 ns, respectively. We have developed three types of devices which differ in the way a terahertz signal is coupled to the detector and cover the following ranges: 0.3–3 THz, 0.1–30 THz and 25–70 THz. In the case of the receiving system optimized for 0.3–3 THz, the sensitive element (a strip of asuperconductor with planar dimensions of 0.2μm (length) by 1.7μm (width)) was integrated witha planar broadband log-spiral antenna. For additional focusing ofthe incident radiation a silicon hyperhemispherical lens was used. For the 0.1–30 THz receivingsystem, the sensitive element was patterned as parallel strips(2μm wide each) filling an area of 500×500μm2with a filling factor of 0.5. In the receivingsystem of this type we used direct coupling of the incident radiation to the sensitive element. Inthe 25–70 THz range (detector type 2/2a in Table 1) we used a square-shaped superconductingdetector with planar dimensions of 10×10μm2. Incident radiation was coupled to the detectorwith the use of a germanium hyperhemispherical lens.The response time of the above receiving systems is determined by the cooling rate of the hotelectrons in the film. That depends on the electron-phonon interaction time, which is less forultrathin NbN than in MoRe.
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Goltsman, G. (2009). Superconducting NbN hot-electron bolometer mixer, direct detector and single-photon counter: from devices to systems.
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Treuttel, J., Thomas, B., Maestrini, A., Wang, H., Alderman, B., Siles, J. V., et al. (2009). A 380 GHz sub-harmonic mixer using MMIC foundry based Schottky diodes transferred onto quartz substrate. In Proc. 20th Int. Symp. Space Terahertz Technol.. Charlottesville, Virginia, USA.
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Meledin, D., Pavolotsky, A., Desmaris, V., Lapkin, I., Risacher, C., Perez, V., et al. (2009). A 1.3-THz balanced waveguide HEB mixer for the APEX telescope. IEEE Trans. Microw. Theory Techn., 57(1), 89–98.
Abstract: In this paper, we report about the development, fabrication, and characterization of a balanced waveguide hot electron bolometer (HEB) receiver for the Atacama Pathfinder EXperiment telescope covering the frequency band of 1.25–1.39 THz. The receiver uses a quadrature balanced scheme and two HEB mixers, fabricated from 4- to 5-nm-thick NbN film deposited on crystalline quartz substrate with an MgO buffer layer in between. We employed a novel micromachining method to produce all-metal waveguide parts at submicrometer accuracy (the main-mode waveguide dimensions are 90×180 μm). We present details on the mixer design and measurement results, including receiver noise performance, stability and “first-light†at the telescope site. The receiver yields a double-sideband noise temperature averaged over the RF band below 1200 K, and outstanding stability with a spectroscopic Allan time more than 200 s.
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Ryabchun, S., Tong, C. - Y. E., Blundell, R., & Gol'tsman, G. (2009). Stabilization scheme for hot-electron bolometer receivers using microwave radiation. IEEE Trans. Appl. Supercond., 19(1), 14–19.
Abstract: We present the results of a stabilization scheme for terahertz receivers based on NbN hot-electron bolometer (HEB) mixers that uses microwave radiation with a frequency much lower than the gap frequency of NbN to compensate for mixer current fluctuations. A feedback control loop, which actively controls the power level of the injected microwave radiation, has successfully been implemented to stabilize the operating point of the HEB mixer. This allows us to increase the receiver Allan time to 10 s and also improve the temperature resolution of the receiver by about 30% in the total power mode of operation.
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Lieberzeit, P. A., & Dickert, F. L. (2009). Chemosensors in environmental monitoring: challenges in ruggedness and selectivity. Anal Bioanal Chem, 393(2), 467–472.
Abstract: Environmental analysis is a potential key application for chemical sensors owing to their inherent ability to detect analytes on-line and in real time in distributed systems. Operating a chemosensor in a natural environment poses substantial challenges in terms of ruggedness, long-term stability and calibration. This article highlights current trends of achieving both the necessary selectivity and ruggedness: one way is deploying sensor arrays consisting of robust broadband sensors and extracting information via chemometrics. If using only a single sensor is desired, molecularly imprinted polymers offer a straightforward way for designing artificial recognition materials. Molecularly imprinted polymers can be utilized in real-life environments, such as water and air, aiming at detecting analytes ranging from small molecules to entire cells.
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Parrott, E. P. J., Zeitler, J. A., Fris<cc><152>c<cc><152>ic<cc><81>, T., Pepper, M., Jones, W., Day, G. M., et al. (2009). Testing the sensitivity of terahertz spectroscopy to changes in molecular and supramolecular structure: a study of structurally similar cocrystals. Crystal Growth & Design, 9(3), 1452–1460.
Abstract: Terahertz time-domain-spectroscopy (THz-TDS) has emerged as a versatile spectroscopic technique, and an alternative to powder X-ray diffraction in the characterization of molecular crystals. We tested the ability of terahertz spectroscopy to distinguish between chiral and racemic hydrogen-bonded cocrystals that are similar in molecular and supramolecular structure. Terahertz spectroscopy readily distinguished between the isostructural cocrystals of theophylline with chiral and racemic forms of malic acid which are almost identical in molecular structure and supramolecular architecture. Similarly, the cocrystals of theophylline with chiral and racemic forms of tartaric acid, which are similar at the molecular level but dissimilar in crystal packing, were distinguished unequivocally. The investigation of the same cocrystals using X-ray powder diffraction and Raman spectroscopy suggested that THz-TDS is comparable in sensitivity to diffraction methods and more sensitive than Raman spectroscopy to changes in cocrystal architecture. The differences in spectra acquired by THz-TDS could be further enhanced by cooling the samples to 109 K.
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Минаева, О. В. (2009). Быстродействующий однофотонный детектор на основе тонкой сверхпроводниковой пленки NbN. Ph.D. thesis, , .
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Ryabchun, S. A., Tretyakov, I. V., Finkel, M. I., Maslennikov, S. N., Kaurova, N. S., Seleznev, V. A., et al. (2009). NbN phonon-cooled hot-electron bolometer mixer with additional diffusion cooling. In Proc. 20th Int. Symp. Space Terahertz Technol. (pp. 151–154). Charlottesville, USA.
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