1. |
- Arridge, Christopher S., et al.
(författare)
-
Uranus Pathfinder : exploring the origins and evolution of Ice Giant planets
- 2012
-
Ingår i: Experimental astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 33:2-3, s. 753-791
-
Tidskriftsartikel (refereegranskat)abstract
- The "Ice Giants" Uranus and Neptune are a different class of planet compared to Jupiter and Saturn. Studying these objects is important for furthering our understanding of the formation and evolution of the planets, and unravelling the fundamental physical and chemical processes in the Solar System. The importance of filling these gaps in our knowledge of the Solar System is particularly acute when trying to apply our understanding to the numerous planetary systems that have been discovered around other stars. The Uranus Pathfinder (UP) mission thus represents the quintessential aspects of the objectives of the European planetary community as expressed in ESA's Cosmic Vision 2015-2025. UP was proposed to the European Space Agency's M3 call for medium-class missions in 2010 and proposed to be the first orbiter of an Ice Giant planet. As the most accessible Ice Giant within the M-class mission envelope Uranus was identified as the mission target. Although not selected for this call the UP mission concept provides a baseline framework for the exploration of Uranus with existing low-cost platforms and underlines the need to develop power sources suitable for the outer Solar System. The UP science case is based around exploring the origins, evolution, and processes at work in Ice Giant planetary systems. Three broad themes were identified: (1) Uranus as an Ice Giant, (2) An Ice Giant planetary system, and (3) An asymmetric magnetosphere. Due to the long interplanetary transfer from Earth to Uranus a significant cruise-phase science theme was also developed. The UP mission concept calls for the use of a Mars Express/Rosetta-type platform to launch on a Soyuz-Fregat in 2021 and entering into an eccentric polar orbit around Uranus in the 2036-2037 timeframe. The science payload has a strong heritage in Europe and beyond and requires no significant technology developments.
|
|
2. |
- Siebert, Ronald, et al.
(författare)
-
Fluorescence quenching in Zn2+-bis-terpyridine coordination polymers: a single molecule study
- 2012
-
Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 1364-5501 .- 0959-9428. ; 22:31, s. 16041-16050
-
Tidskriftsartikel (refereegranskat)abstract
- A Zn2+-bis-terpyridine coordination polymer is investigated by single-molecule fluorescence spectroscopy (SMS). The bis-terpyridine ligands of the coordination polymers bear conjugated chromophores connecting the terpyridine spheres of the ligands, which resemble structural features of MEH-PPV. To the best of our knowledge this paper presents the first systematic SMS study on Zn2+-bis-terpyridine coordination polymers. Upon incorporation of free chromophores into the polymer, the fluorescence quantum yield of individual chromophores appears to be reduced. The reason for the reduced emission per chromophore in a polymer is investigated by brightness studies on single isolated polymer molecules. Furthermore, the experiments reveal that the Zn2+-bis-terpyridine coordination polymer contains a significantly larger fraction of effective chromophores, compared to one of the most common conjugated polymers, e. g., MEH-PPV. This finding is attributed to the particularly rigid geometry of the system at hand, which was corroborated by polarization-dependent experiments. Time-resolved experiments identified two different types of intensity fluctuations: small amplitude intensity fluctuations might correlate with switching of individual chromophores by structural fluctuations, while large amplitude jumps switch off the emission of the entire molecule. Finally, experiments under different atmospheric conditions offer further insights into the molecular mechanism and the nature of the quenchers involved in the blinking.
|
|