Aqueous alteration of polycyclic aromatic hydrocarbons in asteroids and meteorites

Please apply before October 1st, 2013

Polycyclic aromatic hydrocarbons (PAHs) have been detected in a wide range of environments, starting from the interstellar medium (ISM) where they are formed in situ, to solar system objects, such as meteorites. However, the PAHS detected in the interstellar medium are much larger (up to C50 and C60) then the compounds found in meteorites. For at least two carbonaceous chondrites (Allende and Murchison) it has been suggested that the PAHs present in these meteorites predate their formation, so are likely to originate from the ISM. Very recently a survey was performed on what are the one hundred mineralogical questions impacting the future of Earth, planetary, and environmental sciences. One of the questions listed here was "What role, if any, have minerals played in the diversity of organic matter in carbonaceous asteroids?" Closely related to this question is the effect of water in this context. For example, it has been suggested that amino acids could be synthesized in carbonaceous chondrites by aqueous alteration of PAHs. Metasomatism, the chemical alteration of a rock by hydrothermal fluids is also suggested to play a large role in meteoritic alteration. This process is so far mainly studied in the context of the mineralogy of chondritic meteorites. However, this hydrothermal alteration could also significantly affect the PAH content of these chondrites. If we assume that indeed some of the PAH material found in meteorites originates from the ISM, then it is likely that the large C50, C60 compounds are incorporated in meteorites as well. These

have, however, never been detected. This project focuses on the key question if aqueous alteration could be mechanism to break down the larger PAHs into smaller PAHs and other organic compounds that are detected in meteorites. The primary goal of this proposal – that comprises a 4-year PhD project - is to experimentally investigate the effect of water and high temperature on PAHs embedded in meteoritic mineral matrices. Our experiments will focus on the interaction between PAHs and water, PAHs and minerals, and PAHs and minerals and water under different temperature conditions.

Requirements are a broad interest in geosciences, chemistry, and astronomy and a willingness to interact across scientific disciplines. We are looking for an enthusiastic person with a background in experimental and analytical methods relevant to this research – specifically, Raman spectroscopy and scanning/transmission electron microscopy techniques. While students work on their own PhD projects, good interaction with others in the group will be key to success.

Please contact Dr. ten Kate at i.l.tenkate@uu.nl, with cc to Prof. Tielens (tielens@strw.leidenuniv.nl) and Dr. Plümper (O.Plumper@uu.nl), for more information and to obtain a full description of the project. This description can also be found on www.ingeloes.com/jobs.