Dissociative electron attachment

Dissociative electron attachment (DEA) is the process wherein an electron attaches onto a molecule and causes it to dissociate and / or fragment. The sizes of the molecules chosen to undergo DEA are comparatively enormous to the size of the attached electron (remember, electrons are tiny, tiny substituents of atoms, which in turn, bind together to form molecules). The process of DEA can thus be compared to a mosquito landing on the head of an elephant and causing its head to fall off!

rgmfygmmgz-8Fragmenting elephants with flies. Because science!

So why do such a violent thing to such innocent little critters like molecules?! Well, generally if we are interested in learning how a piece of machinery works, one may be inclined to take it apart, piece by piece, and then reassemble it back again. It is in fact a very straight-forward and effective method to learn about how stuff works.

The problem with molecules is that they are very, very small. In order to learn about their structure and architecture, inner workings, physical characteristics, and behaviors in times of great distress (e.g. under high-intensity radiation, low pressures, magnetic fields, etc.), we can take them apart, but not really put them back together again. This sort of experimental physical chemistry (or chemical physics) is actually a bit like forensic science, in that we violently disintegrate or fragment molecules with lasers and/or electron beams and photograph the resulting crime scene; documenting all formed fragments to piece together the dynamics of the resultant fragmentation process. In this way we manage to get a glimpse into molecular processes or dynamics which reveal to us information regarding the molecule’s characteristics. Imagine a forensic scientist that blindly shoots someone in some part of the body and then documents everything that happened in order to study exactly how that someone lost an arm and a leg. That’s what I do.

20160903_101510My work station. Where the magic happens. By magic I mean science. 

The importance of DEA research cannot be overstated. Electron transfer is an elementary process in many chemical and biochemical reactions. Transferring electrons is one of the first things you learn about in chemistry in oxidation/reduction reactions. These include important reactions that allow us to extract energy from our food, whole industries are built around chemical reactions where electrons are moved from one chemical to another, even negatively charged molecules can be found in certain regions in space, where they play a key role in maintaining and balancing the chemical enrichment of the cosmos.


The basic premise. An electron (e) attaches to a molecule (AB) and as a result the molecule dissociates into the fragments (A & B).

Without going into too much detail, the molecule I am working on at the moment is H2FeRu3(CO)13 (see below). When an electron attaches onto the molecule a cavalcade of dissociations take place; carbonyl groups (CO) start leaving the molecule, Ruthenium atoms (Ru) and the iron atom (Fe) leave as well along with some carbonyls. I.e. a bunch of different fragmentation channels are possible for the molecule and we are documenting all the fragments, i.e. all the different masses of formed fragments.


A big ass molecule (H2FeRu3(CO)13) with a myriad of dissociative electron attachment channels. Photo courtesy of Ragesh Kumar.

I may go into some more grueling details later regarding the spectra, experimental setup and more. For now, however, I’m going to continue reading up on the subject by reading the two reviews my new instructor (Prof. O. Ingólfsson) co-wrote.

See: Bald, Langer, Tegeder, Ingólfsson. International Journal of Mass Spectrometry, 2008, 277, 4-25. & Ingólfsson, Weik, Illenberger. Internation Journal of Mass Spectrometry and Ion Processes, 1996, 155, 1-68.

2 thoughts on “Dissociative electron attachment

  1. From this post, it seems astrochemistry is more physics or inorganic chemistry-oriented than organic chemistry-oriented. Would it be safe to assume this?
    Also, when considering your day-to-day role as an astrochemist, do you undertake much theoretical research? What would you say is the ratio between theoretical and experimental research in astrochemistry. I would consider this as a possible career path in the future, if the hands-on procedures aren’t especially rigorous.


    1. To be clear, the project I was working on I’m describing here was not astrochemistry oriented but rather had more connections with nanotech. Not that dissociative electron attachment is not an astrochemical process, it absolutely is, but the molecules I was working on at this point are not astronomically relevant.

      Astrochemistry does include a lot of organic chemistry, but mostly in the solid state catalyzed by UV light and thermal energy.

      Astrochemistry is a broad field and the deeper you go and you can definitely make your own path.

      I would like to undertake more theoretical work but currently my workload is too large to properly work on that skillset and so at the moment I am collaborating with experts in theoretical chemistry and chemical modelling. Some people do both lab work and theoretical work and others focus on one.

      The thing is that you don’t need to be a lab rat (like I am) to be an astrochemist. You can take the theoretical route and specialize in the electronic structures of astronomically relevant molecules. Or if you are good at coding you can go the chemical modelling route and build chemical networks that predict and explain observed abundances of molecules in various interstellar regions.

      The bottom line is that you make your own path.


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