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Tol, J. van; Brunel, L.-C.; Wylde, R. J. |
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A quasioptical transient electron spin resonance spectrometer operating at 120 and 240 GHz |
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Journal Article |
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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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Schottky, noise temperature |
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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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Gao, G. R.; Hovenier, J. N.; Yang, Z. Q.; Baselmans, J. J. A.; Baryshev, A.; Hajenius, M.; Klapwijk, T. M.; Adam, A. J. L.; Klaassen, T. O.; Williams, B. S.; Kumar, S.; Hu, Q.; Reno, J. L. |
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A novel terahertz heterodyne receiver based on a quantum cascade laser and a superconducting bolometer |
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Conference Article |
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2005 |
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Proc. 16th Int. Symp. Space Terahertz Technol. |
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19-23 |
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Göteborg, Sweden |
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RPLAB @ s @ qc_lasers_gao_isstt16 |
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367 |
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Morozov, D. V.; Smirnov, K. V.; Smirnov, A. V.; Lyakhov, V. A.; Goltsman, G. N. |
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A millimeter-submillimeter phonon-cooled hot-electron bolometer mixer based on two-dimensional electron gas in an AlGaAs/GaAs heterostructure |
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Journal Article |
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2005 |
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Semicond. |
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Semicond. |
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39 |
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9 |
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1082-1086 |
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2D electron gas, AlGaAs/GaAs heterostructures, mixers |
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Experimental results obtained by studying the main characteristics of a millimeter-submillimeter wave mixer based on the hot-electron effect in a two-dimensional electron gas in a AlGaAs/GaAs heterostructure with a phonon-scattering cooling mechanism for charge carriers are reported. The gain bandwidth of the mixer is 4 GHz, the internal conversion losses are 13 dB, and the optimum local-oscillator power is 0.5 μW (for a mixer area of 1 μm2). It is shown that a millimeter-submillimeter-wave receiver with a noise temperature of 1900 K can be developed on the basis of a AlGaAs/GaAs mixer. This mixer also appears to be promising for use in array receiver elements. |
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1063-7826 |
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Kinch, M. A.; Wan, C.-F., Beck, J. D. |
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1/f noise in HgCdTe photodiodes |
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2005 |
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J. Electron. Mater. |
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34 |
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6 |
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928-932 |
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HgCdTe |
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