Semiconducting carbon nanotube transistors with channel lengths exceeding 300 microns have been fabricated. In these long transistors, carrier transport is diffusive and the channel resistance dominates the transport. Transport characteristics are used to extract the field-effect mobility (79 000 cm2/Vs) and estimate the intrinsic mobility (>100 000 cm2/Vs) at room temperature. These values exceed those for all known semiconductors, which bodes well for application of nanotubes in high-speed transistors, single- and few-electron memories, and chemical/biochemical sensors.

The Mars Organic Molecule Analyzer (MOMA) instrument onboard the ESA/Roscosmos ExoMars rover (to launch in July, 2020) will analyze volatile and refractory organic compounds in martian surface and subsurface sediments. In this study, we describe the design, current status of development, and analytical capabilities of the instrument. Data acquired on preliminary MOMA flight-like hardware and experimental setups are also presented, illustrating their contribution to the overall science return of the mission. Key Words: Mars—Mass spectrometry—Life detection—Planetary instrumentation. Astrobiology 17, 655–685.

Here we describe the design, single-molecule transport measurements, and theoretical modeling of a ferrocene-based organometallic molecular wire, whose bias-dependent conductance shows a clear Lorentzian form with magnitude exceeding 70% of the conductance quantum G_0. We attribute this unprecedented level of single-molecule conductance to a manifestation of the low-lying molecular resonance and extended orbital network long-predicted for a conjugated organic system. A similar-in-length, all-organic conjugated phenylethynyl oligomer molecular framework shows much lower conductance.Comment: 11 pages text, 4 figures, 4 pages supplementary material; re-submitted to Physical Review Letter

The Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging (DAVINCI) mission described herein has been selected for flight to Venus as part of the NASA Discovery Program. DAVINCI will be the first mission to Venus to incorporate science-driven flybys and an instrumented descent sphere into a unified architecture. The anticipated scientific outcome will be a new understanding of the atmosphere, surface, and evolutionary path of Venus as a possibly once-habitable planet and analog to hot terrestrial exoplanets. The primary mission design for DAVINCI as selected features a preferred launch in summer/fall 2029, two flybys in 2030, and descent-sphere atmospheric entry by the end of 2031. The in situ atmospheric descent phase subsequently delivers definitive chemical and isotopic composition of the Venus atmosphere during an atmospheric transect above Alpha Regio. These in situ investigations of the atmosphere and near-infrared (NIR) descent imaging of the surface will complement remote flyby observations of the dynamic atmosphere, cloud deck, and surface NIR emissivity. The overall mission yield will be at least 60 Gbits (compressed) new data about the atmosphere and near surface, as well as the first unique characterization of the deep atmosphere environment and chemistry, including trace gases, key stable isotopes, oxygen fugacity, constraints on local rock compositions, and topography of a tessera.

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Achieving L2MS in a highly miniaturized instrument enables a powerful approach to the detection and characterization of aromatic organics in remote terrestrial and planetary applications. Tunable detection of molecular and fragment ions with high mass resolution, diagnostic of molecular structure, is possible on such a compact L2MS instrument. The selectivity of L2MS against low-mass inorganic salt interferences is a key advantage when working with unprocessed, natural samples, and a mechanism for the observed selectivity is proposed.

International audienceThis paper describes strategies to search for, detect, and identify organic material on the surface and subsurface of Mars. The strategies described include those applied by landed missions in the past and those that will be applied in the future. The value and role of ESA's ExoMars rover and of her key science instrument Mars Organic Molecule Analyzer (MOMA) are critically assessed

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