Spectroscopic Characterization of Key Aromatic Molecules: A Route toward The Origin of Life.

To gain information on the abiotic synthesis of the building blocks of life from simple molecules, and their subsequent chemical evolution to biological systems, the starting point is the identification of target species in Titan-like planets, i.e., planets that resemble the primitive Earth, as well as in Earth-like planets in the habitable zone of their star, namely planets where life can be already originated. In this scenario, molecular spectroscopy plays a crucial role because spectroscopic signatures are at the basis of an unequivocal proof for the presence of these target molecules. Thanks to the advances in many different techniques and to the NASA successful Kepler exoplanet transit mission, thousands of diverse planets outside of our solar system have been discovered. The James Webb Space Telescope (JWST), scheduled to be launched in 2018, will be very helpful in the identification of biosignature gases in Earth-like planets' atmospheres and of prebiotic molecule signatures in Titan-like atmospheres by observing their absorption during transits. While the search for key-target molecules in exoplanet atmospheres can be carried out by the JWST Transit Spectroscopy in the infrared (IR) region (0.6 - 29 µm wavelength range), opportunities for their detection in protostellar cores, protoplanetary disks and on Titan are also offered by the interferometric high spectral and spatial resolution observations using the Atacama Large Millimeter/submillimeter Array (ALMA). In the present work, target molecules have been selected and their spectroscopic characterization presented in view of supporting their infrared and complementary millimeter/submillimeter-wave spectral observations. In detail, the selected target molecules include: (1) the three-membered oxygen-containing heterocycles: oxirane and protonated oxirane, (2) the cyclopropenyl cation and its methyl derivative, (3) two examples of ortho- and peri-fused tri-cyclic aromatic rings, i.e., the phenalenyl cation (C13H9+) and anion (C13H9-), and (4) uracil, a specific RNA base.

Tunable Broadband Nanocarbon Transparent Conductor by Electrochemical Intercalation.

Optical transparent and electrical conducting materials with broadband transmission are important for many applications in optoelectronic, telecommunications, and military devices. However, studies of broadband transparent conductors and their controlled modulation are scarce. In this study, we report that reversible transmittance modulation has been achieved with sandwiched nanocarbon thin films (containing carbon nanotubes (CNTs) and reduced graphene oxide (rGO)) via electrochemical alkali-ion intercalation/deintercalation. The transmittance modulation covers a broad range from the visible (450 nm) to the infrared (5 µm), which can be achieved only by rGO rather than pristine graphene films. The large broadband transmittance modulation is understood with DFT calculations, which suggest a decrease in interband transitions in the visible range as well as a reduced reflection in the IR range upon intercalation. We find that a larger interlayer distance in few-layer rGO results in a significant increase in transparency in the infrared region of the spectrum, in agreement with experimental results. Furthermore, a reduced plasma frequency in rGO compared to few-layer graphene is also important to understand the experimental results for broadband transparency in rGO. The broadband transmittance modulation of the CNT/rGO/CNT systems can potentially lead to electrochromic and thermal camouflage applications.

Nanocarbon Paper: Flexible, High Temperature, Planar Lighting with Large Scale Printable Nanocarbon Paper (Adv. Mater. 23/2016).

On page 4684, C. Dames, L. Hu and co-workers report highly efficient, broadband lighting from printed hybrid nanocarbon structures with carbon nanotubes and reduced graphene oxides. The fast response and excellent stability of the flexible lighting can find applications in a range of emerging applications where the shape and format, as well as being lightweight, are important.

Flexible, High Temperature, Planar Lighting with Large Scale Printable Nanocarbon Paper.

Highly efficient broadband thermal radiation from reduced graphene oxide (RGO) paper mixed with single-walled carbon nanotubes (CNTs) is reported. These RGO-CNT paper ribbons routinely reach 3000 K before failure, with some samples exceeding 3300 K, higher than any other carbon nanomaterial. Excellent performance is achieved, with ≈90% radiation efficiency, 200 000 on/off cycles, and stable operation for more than 50 hours.