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Tol, J. van; Brunel, L.-C.; Wylde, R. J. |
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Title |
A quasioptical transient electron spin resonance spectrometer operating at 120 and 240 GHz |
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Year |
2005 |
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Rev. Sci. Instrum. |
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Rev. Sci. Instrum. |
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76 |
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7 |
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074101 (1 to 8) |
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Keywords |
Schottky, noise temperature |
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Abstract |
A new multifrequency quasioptical electron paramagnetic resonance (EPR) spectrometer is described. The superheterodyne design with Schottky diode mixer/detectors enables fast detection with subnanosecond time resolution. Optical access makes it suitable for transient EPR (TR-EPR) at 120 and 240 GHz. These high frequencies allow for an accurate determination of small g-tensor anisotropies as are encountered in excited triplet states of organic molecules like porphyrins and fullerenes. The measured concentration sensitivity for continuous-wave (cw) EPR at 240 GHz and at room temperature without cavity is 1013 spins/cm3 (15 nM) for a 1 mT linewidth and a 1 Hz bandwidth. With a Fabry-Perot cavity and a sample volume of 30 nl, the sensitivity at 240 GHz corresponds to [approximate]3×109 spins for a 1 mT linewidth. The spectrometer's performance is illustrated with applications of transient EPR of excited triplet states of organic molecules, as well as cw EPR of nitroxide reference systems and a thin film of a colossal magnetoresistance material. |
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Actually, noise spectral density is given (3e-19 W/Hz) |
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588 |
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Thijs de Graauw; Nick Whyborn; Frank Helmich; Pieter Dieleman; Peter Roelfsema; Emmanuel Caux; Tom Phillips; Jürgen Stutzki; Douwe Beintema; Arnold Benz; Nicolas Biver; Adwin Boogert; Francois Boulanger; Sergey Cherednichenko; Odile Coeur-Joly; Claudia Comito; Emmanuel Dartois; Albrecht de Jonge; Gert de Lange; Ian Delorme; Anna DiGiorgio; Luc Dubbeldam; Kevin Edwards; Michael Fich; Rolf Güsten; Fabrice Herpin; Netty Honingh; Robert Huisman; Herman Jacobs; Willem Jellema; Jon Kawamura; Do Kester; Teun Klapwijk; Thomas Klein; Jacob Kooi; Jean-Michel Krieg; Carsten Kramer; Bob Kruizenga; Wouter Laauwen; Bengt Larsson; Christian Leinz; Rene Liseau; Steve Lord; Willem Luinge; Anthony Marston; Harald Merkel; Rafael Moreno; Patrick Morris; Anthony Murphy; Albert Naber; Pere Planesas; Jesus Martin-Pintado; Micheal Olberg; Piotr Orleanski; Volker Ossenkopf; John Pearson; Michel Perault; Sabine Phillip; Mirek Rataj; Laurent Ravera; Paolo Saraceno; Rudolf Schieder; Frank Schmuelling; Ryszard Szczerba; Russell Shipman; David Teyssier; Charlotte Vastel; Huib Visser; Klaas Wildeman; Kees Wafelbakker; John Ward; Roonan Higgins; Henri Aarts; Xander Tielens; Peer Zaal |
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The Herschel-heterodyne instrument for the far-infrared (HIFI): instrument and pre-launch testing |
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Conference Article |
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2008 |
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Proc. SPIE |
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7010 |
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701004 |
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422 |
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Huebers, H.-W.; Semenov, A.; Richter, H.; Birk, M.; Krocka, M.; Mair, U.; Smirnov, K.; Gol’tsman, G. N.; Voronov, B. M. |
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Superconducting hot electron bolometer as mixer for far-infrared heterodyne receivers |
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Conference Article |
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2003 |
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Proc. SPIE |
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Proc. SPIE |
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4855 |
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395-401 |
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NbN HEB mixers |
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Heterodyne receivers for applications in astronomy need quantum limited sensitivity. In instruments which are currently under development for SOFIA or Herschel superconducting hot electron bolometers (HEB) will be used to achieve this goal at frequencies above 1.4 THz. We present results of the development of a phonon-cooled NbN HEB mixer for GREAT, the German Receiver for Astronomy at Terahertz Frequencies, which will be flown aboard SOFIA. The mixer is a small superconducting bridge incorporated in a planar feed antenna and a hyperhemispherical lens. Mixers with logarithmic-spiral and double-slot feed antennas have been investigated with respect to their noise temperature, conversion loss, linearity and beam pattern. At 2.5 THz a double sideband noise temperature of 2200 K was achieved. The conversion loss was 17 dB. The response of the mixer was linear up to 400 K load temperature. The performance was verified by measuring an emission line of methanol at 2.5 THz. The measured linewidth is in good agreement with the linewidth deduced from pressure broadening measurements at millimeter wavelength. The results demonstrate that the NbN HEB is very well suited as a mixer for far-infrared heterodyne receivers. |
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SPIE |
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Tucson, USA |
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Phillips, T. G.; Zmuidzinas, J. |
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Presented at the Society of Photo-Optical Instrumentation Engineers (SPIE) Conference |
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4855 |
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Millimeter and Submillimeter Detectors for Astronomy |
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335 |
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Huebers, H.-W.; Schubert, J.; Semenov, A.; Gol’tsman, G. N.; Voronov, B. M.; Gershenzon, E. M.; Schwaab, G. W. |
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NbN phonon-cooled hot-electron bolometer as a mixer for THz heterodyne receivers |
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Conference Article |
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1999 |
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Proc. SPIE |
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Proc. SPIE |
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3828 |
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410-416 |
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NbN HEB mixers |
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We have investigated a phonon-cooled NbN hot electron bolometric (HEB) mixer in the frequency range from 0.7 THz to 5.2 THz. The device was a 3.5 nm thin film with an in- plane dimension of 1.7 X 0.2 micrometers 2 integrated in a complementary logarithmic spiral antenna. The measured DSB receiver noise temperatures are 1500 K, 2200 K, 2600 K, 2900 K, 4000 K, 5600 K and 8800 K. The sensitivity fluctuation, the long term stability, and the antenna pattern were measured and the suitability of the mixer for a practical heterodyne receiver is discussed. |
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Spie |
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Chamberlain, J.M. |
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Terahertz Spectroscopy and Applications II |
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no |
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1477 |
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Zhang, W.; Li, N.; Jiang, L.; Ren, Y.; Yao, Q.-J.; Lin, Z.-H.; Shi, S.-C.; Voronov, B. M.; Gol’tsman, G. N. |
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Title |
Dependence of noise temperature of quasi-optical superconducting hot-electron bolometer mixers on bath temperature and optical-axis displacement |
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Conference Article |
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Year |
2008 |
Publication |
Proc. SPIE |
Abbreviated Journal |
Proc. SPIE |
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Volume |
6840 |
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684007 (1 to 8) |
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Keywords |
NbN HEB mixers, noise temperature, LO power |
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It is known that the increase of bath temperature results in the decrease of critical current of superconducting hot-electron bolometer (HEB) mixers owing to the depression of superconductivity, thus leading to the degradation of the mixer’s sensitivity. Here we report our study on the effect of bath temperature on the heterodyne mixing performance of quasi-optical superconducting NbN HEB mixers incorporated with a two-arm log-spiral antenna. The correlation between the bath temperature, critical current, LO power requirement and noise temperature is investigated at 0.5 THz. Furthermore, the heterodyne mixing performance of quasi-optical superconducting NbN HEB mixers is examined while there is an optical-axis displacement between the center of the extended hemispherical silicon lens and the superconducting NbN HEB device, which is placed on the back of the lens. Detailed experimental results and analysis are presented. |
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Spie |
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Zhang, C.; Zhang, X.-C. |
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Terahertz Photonics |
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1415 |
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