Effect of molecular and electronic structure on the light harvesting properties of dye sensitizers

The systematic trends in structural and electronic properties of perylene diimide (PDI) derived dye molecules have been investigated by DFT calculations based on projector augmented wave (PAW) method including gradient corrected exchange-correlation effects. TDDFT calculations have been performed to study the visible absorbance activity of these complexes. The effect of different ligands and halogen atoms attached to PDI were studied to characterize the light harvesting properties. The atomic size and electronegativity of the halogen were observed to alter the relaxed molecular geometries which in turn influenced the electronic behavior of the dye molecules. Ground state molecular structure of isolated dye molecules studied in this work depends on both the halogen atom and the carboxylic acid groups. DFT calculations revealed that the carboxylic acid ligands did not play an important role in changing the HOMO-LUMO gap of the sensitizer. However, they serve as anchor between the PDI and substrate titania surface of the solar cell or photocatalyst. A commercially available dye-sensitizer, ruthenium bipyridine (RuBpy), was also studied for electronic and structural properties in order to make a comparison with PDI derivatives for light harvesting properties. Results of this work suggest that fluorinated, chlorinated, brominated, and iyodinated PDI compounds can be useful as sensitizers in solar cells and in artificial photosynthesis.Comment: Single pdf file, 14 pages with 7 figures and 4 table

The Arctic in Rapid Transition (ART) Initiative: Integrating priorities for Arctic Marine Science over the next decade.

GC23E-0960: The Arctic is undergoing rapid environmental and economic transformations. Recent climate warming, which is simplifying access to oil and gas resources, enabling trans-Arctic shipping, and shifting the distribution of harvestable resources, has brought the Arctic Ocean to the top of national and international political agendas. Scientific knowledge of the present status of the Arctic Ocean and the process-based understanding of the mechanics of change are urgently needed to make useful predictions of future conditions throughout the Arctic region. These are required to plan for the consequences of climate change. A step towards improving our capacity to predict future Arctic change was undertaken with the Second International Conference on Arctic Research Planning (ICARP II) meetings in 2005 and 2006, which brought together scientists, policymakers, research managers, Arctic residents, and other stakeholders interested in the future of the Arctic region. The Arctic in Rapid Transition (ART) Initiative developed out of the synthesis of the several resulting ICARP II science plans specific to the marine environment. This process has been driven by the early career scientists of the ICARP II Marine Roundtable. The ART Initiative is an integrative, international, multi-disciplinary, long-term pan-Arctic program to study changes and feedbacks among the physical characteristics and biogeochemical cycles of the Arctic Ocean. The first ART workshop was held in Fairbanks, Alaska in November 2009 with 58 participants. Workshop discussions and reports were used to develop a science plan that integrates, updates, and develops priorities for Arctic Marine Science over the next decade. The science plan was endorsed by endorsed and sponsored by the IASC SSC "Marine System", the former Arctic Ocean Science Board (AOSB). The next step now is to develop the ART Implementation Plan in order to further the goals of ART during the second ART workshop in Winnipeg, Canada. Our focus within the ART Initiative will be to bridge gaps in knowledge not only across disciplinary boundaries (e.g., biology, geochemistry, geology, meteorology, physical oceanography), but also across geographic (e.g., intenational boundaries, shelves, margins, and the central Arctic Ocean) and temporal boundaries (e.g., paleo/geologic records, current process observations, and future modeling studies). This approach of the ART Initiative will provide a means to better understand and predict change, particularly the consequences for biological productivity, and ultimate responses in the Arctic Ocean system. More information about the ART Initiative can be found at http://www.aosb.org/art.html

Arctic in Rapid Transition (ART)An initiative to integrate priorities for Arctic Marine Science over the next decade

The Arctic is undergoing rapid environmental and economic transformations. Recent climate warming, which is simplifying access to oil and gas resources, enabling trans-Arctic shipping, and shifting the distribution of harvestable resources, has brought the Arctic Ocean to the top of national and international political agendas. Scientific knowledge of the present status of the Arctic Ocean and the process-based understanding of the mechanics of change are urgently needed to make useful predictions of future conditions throughout the Arctic region. A step towards improving our capacity to predict future Arctic change was undertaken with the Second International Conference on Arctic Research Planning (ICARP II) meetings in 2005 and 2006, which brought together scientists, policymakers, research managers, and Arctic residents. The Arctic in Rapid Transition (ART) Initiative developed out of the synthesis of the several resulting ICARP II science plans specific to the marine environment. This process has been driven by the early career scientists of the ICARP II Marine Roundtable. The ART Initiative is an integrative, international, multi-disciplinary, long-term pan-Arctic program to study changes and feedbacks among the physical characteristics and biogeochemical cycles of the Arctic Ocean. The first ART workshop was held in Fairbanks, Alaska in November 2009 with 58 participants. Workshop discussions and reports will be used to develop a science and implementation plan that integrates, updates, and develops priorities for Arctic Marine Science over the next decade. Our focus within the ART Initiative will be to bridge gaps in knowledge not only across disciplinary boundaries (e.g., biology, geochemistry, geology, meteorology, physical oceanography), but also across geographic (e.g., shelves, margins, and the central Arctic Ocean) and temporal boundaries (e.g., paleo/geologic records, current process observations, and future modeling studies. More information about the ART Initiative can be found at http://www.aosb.org/art.html