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| Author |
Krasnopolsky, Vladimir A.; Maillard, Jean Pierre; C. Owen, Tobias |
| Title |
Detection of methane in the martian atmosphere: evidence for life? |
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Journal Article |
| Year |
2004 |
Publication |
Icarus |
Abbreviated Journal |
Icarus |
| Volume |
172 |
Issue |
2 |
Pages |
537-547 |
| Keywords |
FTS, Mars atmosphere, methane absorption lines, IR spectroscopy, infrared spectroscopy, landfill gas |
| Abstract |
Using the Fourier Transform Spectrometer at the Canada–France–Hawaii Telescope, we observed a spectrum of Mars at the P-branch of the strongest CH4 band at 3.3 μm with resolving power of 180,000 for the apodized spectrum. Summing up the spectral intervals at the expected positions of the 15 strongest Doppler-shifted martian lines, we detected the absorption by martian methane at a 3.7 sigma level which is exactly centered in the summed spectrum. The observed CH4 mixing ratio is 10±3 ppb. Total photochemical loss of CH4 in the martian atmosphere is equal to View the MathML source, the CH4 lifetime is 340 years and methane should be uniformly mixed in the atmosphere. Heterogeneous loss of atmospheric methane is probably negligible, while the sink of CH4 during its diffusion through the regolith may be significant. There are no processes of CH4 formation in the atmosphere, so the photochemical loss must therefore be balanced by abiogenic and biogenic sources. Outgassing from Mars is weak, the latest volcanism is at least 10 million years old, and thermal emission imaging from the Mars Odyssey orbiter does not reveal any hot spots on Mars. Hydrothermal systems can hardly be warmer than the room temperature at which production of methane is very low in terrestrial waters. Therefore a significant production of hydrothermal and magmatic methane is not very likely on Mars. The calculated average production of CH4 by cometary impacts is 2% of the methane loss. Production of methane by meteorites and interplanetary dust does not exceed 4% of the methane loss. Methane cannot originate from an extinct biosphere, as in the case of “natural gas†on Earth, given the exceedingly low limits on organic matter set by the Viking landers and the dry recent history which has been extremely hostile to the macroscopic life needed to generate the gas. Therefore, methanogenesis by living subterranean organisms is a plausible explanation for this discovery. Our estimates of the biomass and its production using the measured CH4 abundance show that the martian biota may be extremely scarce and Mars may be generally sterile except for some oases. |
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879 |
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Lobanov, Yury; Shcherbatenko, Michael; Shurakov, Alexander; Rodin, Alexander V.; Klimchuk, Artem; Nadezhdinsky, Alexander I.; Maslennikov, Sergey; Larionov, Pavel; Finkel, Matvey; Semenov, Alexander; Verevkin, Aleksandr A.; Voronov, Boris M.; Ponurovsky, Yakov; Klapwijk, Teunis M.; Gol'tsman, Gregory N. |
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Heterodyne detection at near-infrared wavelengths with a superconducting NbN hot-electron bolometer mixer |
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Journal Article |
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2014 |
Publication |
Opt. Lett. |
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39 |
Issue |
6 |
Pages |
1429-1432 |
| Keywords |
HEB, zebra, IR, infrared |
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We report on the development of a highly sensitive optical receiver for heterodyne IR spectroscopy at the communication wavelength of 1.5 μm (200 THz) by use of a superconducting hot-electron bolometer. The results are important for the resolution of narrow spectral molecular lines in the near-IR range for the study of astronomical objects, as well as for quantum optical tomography and fiber-optic sensing. Receiver configuration as well as fiber-to-detector light coupling designs are discussed. Light absorption of the superconducting detectors was enhanced by nano-optical antennas, which were coupled to optical fibers. An intermediate frequency (IF) bandwidth of about 3 GHz was found in agreement with measurements at 300 GHz, and a noise figure of about 25 dB was obtained that was only 10 dB above the quantum limit. |
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906 |
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Teich, M. C. |
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Infrared heterodyne detection |
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Conference Article |
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1968 |
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Proc. IEEE |
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56 |
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1 |
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37-46 |
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minimum detectable power, quantum limit, infrared, IR mixer |
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Heterodyne experiments have been performed in the middle infrared region of the electromagnetic spectrum using the CO2laser as a radiation source. Theoretically optimum operation has been achieved at kHz heterodyne frequencies using photoconductive Ge:Cu detectors operated at 4°K, and at kHz and MHz frequencies using Pb1-xSnxSe photovoltaic detectors at 77°K. In accordance with the theory, the minimum detectable power observed is a factor of 2/η greater than the theoretically perfect quantum counter, hvΔf. The coefficient 2/η varies from 5 to 25 for the detectors investigated in this study. A comparison is made between photoconductive and photodiode detectors for heterodyne use in the infrared, and it is concluded that both are useful. Heterodyne detection at 10.6 µm is expected to be useful for communications applications, infrared radar, and heterodyne spectroscopy. It has particular significance because of the high radiation power available from the CO2laser, and because of the 8 to 14 µm atmospheric window. |
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IEEE |
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0018-9219 |
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1060 |
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Pyatkov, F.; Khasminskaya, S.; Kovalyuk, V.; Hennrich, F.; Kappes, M. M.; Goltsman, G. N.; Pernice, W. H. P.; Krupke, R. |
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Sub-nanosecond light-pulse generation with waveguide-coupled carbon nanotube transducers |
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Journal Article |
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2017 |
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Beilstein J. Nanotechnol. |
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Beilstein J. Nanotechnol. |
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8 |
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38-44 |
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carbon nanotubes; CNT; infrared; integrated optics devices; nanomaterials |
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Carbon nanotubes (CNTs) have recently been integrated into optical waveguides and operated as electrically-driven light emitters under constant electrical bias. Such devices are of interest for the conversion of fast electrical signals into optical ones within a nanophotonic circuit. Here, we demonstrate that waveguide-integrated single-walled CNTs are promising high-speed transducers for light-pulse generation in the gigahertz range. Using a scalable fabrication approach we realize hybrid CNT-based nanophotonic devices, which generate optical pulse trains in the range from 200 kHz to 2 GHz with decay times below 80 ps. Our results illustrate the potential of CNTs for hybrid optoelectronic systems and nanoscale on-chip light sources. |
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Department of Materials and Earth Sciences, Technische Universitat Darmstadt, Darmstadt 64287, Germany |
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2190-4286 |
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PMID:28144563; PMCID:PMC5238692 |
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RPLAB @ kovalyuk @ |
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1109 |
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Ferrari, S.; Kovalyuk, V.; Hartmann, W.; Vetter, A.; Kahl, O.; Lee, C.; Korneev, A.; Rockstuhl, C.; Gol'tsman, G.; Pernice, W. |
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Hot-spot relaxation time current dependence in niobium nitride waveguide-integrated superconducting nanowire single-photon detectors |
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Journal Article |
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2017 |
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Opt. Express |
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Opt. Express |
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25 |
Issue |
8 |
Pages |
8739-8750 |
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SSPD, SNSPD, photon counting; Infrared; Quantum detectors; Integrated optics; Multiphoton processes; Photon statistics |
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We investigate how the bias current affects the hot-spot relaxation dynamics in niobium nitride. We use for this purpose a near-infrared pump-probe technique on a waveguide-integrated superconducting nanowire single-photon detector driven in the two-photon regime. We observe a strong increase in the picosecond relaxation time for higher bias currents. A minimum relaxation time of (22 +/- 1)ps is obtained when applying a bias current of 50% of the switching current at 1.7 K bath temperature. We also propose a practical approach to accurately estimate the photon detection regimes based on the reconstruction of the measured detector tomography at different bias currents and for different illumination conditions. |
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RPLAB @ kovalyuk @ |
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