This is a bit overdue, but better late than never.
Just over a month ago I came crashing into Leiden from Paris, thus starting my two-year Marie Curie Fellowship at the Leiden Observatory. The landing was a tad rough I must admit. Simultaneously moving in officially with my partner and starting this postdoc without a moment to breathe, I was thrown head-first into the throes of Dutch bureaucracy, coming to terms with two new experimental setups performing very different types of measurements whilst continuing to tie up loose ends from my previous postdoc whilst building a beautiful home for myself and my girlfriend. Just to add insult to injury (or icing on the cake, depending on how half-full your glass is) I went on a ten-day tour around Europe with my band Misþyrming, less than three weeks after my move-in date. During the tour I had a paper accepted in the Journal of Physical Chemistry A and I still managed to do some reading and data analysis instead of… well… sleeping.
It has been an eventful transition to put it mildly. But I digress…
The objective of the proposal I wrote along with Prof. Harold Linnartz from the University in Leiden was to use complementary radiation techniques (i.e. not only lasers and shit but beyond the conventional laser techniques) to study the ionization (removal of electrons) and fragmentation (ripping apart) of a group of molecules called Polycyclic Aromatic Hydrocarbons (or PAHs for short). The project’s formal fact sheet can be found here.
A few examples of PAHs
PAHs comprise an infinitely large subset of molecular structures which include a skeleton of carbon atoms bound together in a sheet, with hydrogen atoms bound to the edges. Terrestrially, these molecules are important because they make up the basic structures of soot particles which form during incomplete combustion processes where hydrocarbons (like gasoline) react with oxygen to form not only carbon dioxide (CO2), but a wealth of additional molecules like PAHs which make up the black gunk that is emitted from fossil fuel burning engines.
Even more examples of PAHs.
Interestingly, from telescopic observations, these molecules seem to be omnipresent in interstellar space. As a matter of fact, PAHs are formed when asymptotic giant branch stars (stars at the end of their lifetimes) eject much of their mass into the interstellar medium. Subsequently, these molecules are processed by ultraviolet (UV) radiation in space and my project seeks to characterize the ultimate fate of these molecules as they are photo-processed in an environment as unforgiving as the vastness of space.
Still even more examples of PAHs.
At the same time, I will also be involved in a secondary project that involves the photochemistry that takes place in interstellar ice analogues, i.e. ices grown in a laboratory setting.
Space (or at least the space between stars) is extremely cold. In fact, it seems inconceivable that any sort of chemistry can be found in such extreme environments. Nonetheless, experiments from the 1990’s showed, that an ice mixture cooled down to 20 K (or -253°C or -424°F) which is irradiated with UV radiation, can give rise to a plethora of complex organic molecules (COMs) such as amino acids.
As simple molecules are collected onto interstellar dust grains at the low temperatures of space, they are processed by UV radiation and start forming more complex molecules.
While this is a very exciting (… no pun intended) result, what is required is absolute quantification of the formation of these COMs, rather than just the fact that they can be made. So another objective of mine during my time here in Leiden will be the pursuit of irradiating simple mixtures of interstellar analogues with UV radiation to induce organic chemistry and sub-zero temperatures in a way that allows us to quantify how much of which complex molecules are formed. As a further incentive, it is of great interest to find an upper limit to the complexity of COMs that can be formed in this way. I.e. answer the question: How complex can molecules grow in space?
It is my intention to start writing more updates as the experiments progress so in the meantime, wish me luck!
Live long and awesome!