Engineering topics
Publications and source records attributed to Strauss, Michael.
The Maunakea Spectroscopic Explorer is a next-generation massively multiplexed spectroscopic facility currently under development in Hawaii. It is completely dedicated to large-scale spectroscopic surveys and will enable transformative science. In this white paper we summarize the science case and describe the current state of the project.
We recommend a conceptual design study for a spectroscopic facility in the southern hemisphere comprising a large diameter telescope, fiber system, and spectrographs collectively optimized for massively-multiplexed spectroscopy. As a baseline, we propose an 11.4-meter aperture, optical spectroscopic survey telescope with a five square degree field of view. Using current technologies, the facility could be equipped with 15,000 robotically-controlled fibers feeding spectrographs over 360<λ<1330 nm with options for fiber-fed spectrographs at high resolution and a panoramic IFU at a separate focus. This would enable transformational progress via its ability to access a larger fraction of objects from Gaia, LSST, Euclid, and WFIRST than any currently funded or planned spectroscopic facility. An ESO-sponsored study (arXiv:1701.01976) discussed the scientific potential in ambitious new spectroscopic surveys in Galactic astronomy, extragalactic astronomy, and cosmology. The US community should establish links with European and other international communities to plan for such a powerful facility and maximize the potential of large aperture multi-object spectroscopy given the considerable investment in deep imaging surveys.
Interlayer interactions play an important role in the formation of two-dimensional covalent organic frameworks (2D COFs), yet the effects of monomer structure on COF formation, crystallinity, and susceptibility to exfoliation are not well understood. Here we probe these effects by studying the stacking behavior of imine-linked macrocycles that represent discrete models of 2D COFs. Specifically, macrocycles based on terephthaldehyde (PDA) or 2,5-dimethoxyterephthaldehyde (DMPDA) stack upon cooling molecularly dissolved solutions. Both macrocycles assemble cooperatively with similar Delta H-e values of -97 kJ/mol and -101 kJ/mol, respectively, although the DMPDA macrocycle assembly process showed a more straightforward temperature dependence. Density functional theory calculations of the stacking of PDA macrocycles suggested two stable configurations that were close in energy. Circular dichroism spectroscopy performed on macrocycles bearing chiral side chains revealed a helix reversion process for the PDA macrocycles that was not observed for the DMPDA macrocycles. Given the structural similarity of these monomers, these findings demonstrate that the stacking processes associated with nanotubes derived from these macrocycles, as well as for the corresponding COFs, are complex and susceptible to kinetic traps, casting doubt on the relevance of thermodynamic arguments for improving materials quality. Rather, a deeper understanding of the mechanism of supramolecular polymerization and its interplay with polymerization and error correction during COF synthesis is needed for improved control of the crystallinity and morphology of these emerging materials.
This grant supported research by the investigators through summer salary support for Strauss and Weinberg, support for graduate students at Princeton University and Ohio State University, and travel, visitor, and publication support for the investigators. The grant originally had a duration of 1 year, and it was extended (without additional funding) for an additional year. The impact of the grant was considerable given its relatively modest duration and funding level, in part because it provided 'seed' funding to get Strauss and Weinberg started at new institutions, and in part because it was combined with support from subsequent grants. Here we summarize progress in the three general areas described in the grant proposal: Lyman alpha absorbers and the intergalactic medium, galaxy formation; and large scale structure.