One of the few blogs I follow is “compound interest” (http://www.compoundchem.com/). It combines beautiful info graphics with chemistry facts, and all of it under creative commons license.
This week mass spectrometry is up:
Electrospray ionization is know to be a soft ionization method and it even works well for highly reactive molecules like oligoyns, polymers containing several triple C-C bonds. In this recent paper we demonstrate that our ion beam deposition is just as gentle and we can build structures from these reactive molecules.
Soft-landing electrospray ion beam deposition of sensitive oligoynes on surfaces in vacuum.
G. Rinke, S. Rauschenbach, S. Schrettl, T. N. Hoheisel, J. Blohm, R. Gutzler, F. Rosei, H. Frauenrath and K. Kern
For electrospray ion beam deposition a large amount of molecules is needed to get a reasonable coverage onto the surface. For instance: 1000 ions would make a nice peak in a mass spectrum. The same 1000 molecular ions would barely be found as adsorbates on a surface by scanning probe microscopy.
The biggest losses in an ES-IBD system occur at the vacuum interface. At this place ions are generated from charged droplets. They move, influences by external electric fields, space charge fields, diffusion and hydrodynamic drag. We constructed our own interface with the idea in mind to leverage the hydrodynamic drag: indeed this is the only force that points towards the axis of the capillary.
We were quite surprised to find that with our specially shaped capillary interfaces we achieve magnificent performance of up to 100% transmission for up to 40 nA. With this magnitude of ion current we reach up to 6nA in high vacuum deposition and hence can make a monolayer coverage of a 5 mm diameter sample in approximately 10 minutes. This makes IBD comparable with thermal evaporation and opens the way for commercial applications, if the full intensity of electrosprays, which can be up to mikroamps, can be used.
In our paper in ‘Analyst’ we show the measured transmission characteristics, deposition performance and purity and simulations, which rationalize how our capillary is working.
A hydrodynamically optimized nano-electrospray ionization source and vacuum interface
M Pauly, M Sroka, J Reiss, G Rinke, A Albarghash, R Vogelgesang, H Hahne, B Kuster, J Sesterhenn, K Kern, S Rauschenbach
Analyst, 2014,139, 1856-1867
If two people (groups) have the same idea, it cannot be entirely wrong. The other group which has an STM connect with an electrospray ion beam deposition system (R. Berndts group, Univ. Kiel
) worked in parallel on a very similar project. The adsorption of dyes on surfaces for the purpose of energy conversion seems important enough to immediately trigger the idea to look at it with STM. But: you need an ES-IBD system to do it. Initially also James O’Shea in Nottingham
built his simple electrospray deposition (ESD) source
for that purpose.
We looked at the Ruthenium dye N3 on anatase, which is important for dye sensitized solar cells
. This work was really tough, because the anatase surface is not easy to prepare, but Christopher made it. And then we used a vacuum suitcase (more about those at another time), which can be intense too. Anyhow, we made nice surfaces with N3 on (tested with DINeC mass spectrometry. very cool!
) and the guys at the LT STM measured the electronic structure. Recently our paper came out:
Christopher S Kley, Christian Dette, Gordon Rinke, Christopher E Patrick, Jan Čechal, Soon Jung Jung, Markus Baur, Michael Dürr, Stephan Rauschenbach, Feliciano Giustino, Sebastian Stepanow, Klaus Kern
Nice to compare: the works of the Kiel group and of James O’Shea (not necessarily complete)
Starting Sunday March 2nd I will attend the meeting of the german mass spectrometry society DGMS. The conference takes place in Frankfurt. I even got to present two posters, even though I applied too late. Take a look http://www.dgms2014.uni-frankfurt.de/ .
I supported the work of my colleague Ulrich Stuetzel for a while now and a nice paper came out of his thesis. He really prepared very good graphene nanoribbons. Even after ambient processing in acid (and what not) we were able to image the graphite ridges with atomic resolution on top. Never published that, but below is how the photocurrent images look like in the paper. Nice work of Ulrich.
see in peer reviewed publications
Spatially resolved photocurrents in graphene nanoribbon devices
Eberhard Ulrich Stützel, Thomas Dufaux, Adarsh Sagar, Stephan Rauschenbach, Kannan Balasubramanian, Marko Burghard and Klaus Kern
Applied Physics Letters 102 (2013) 043106
The new year 2013 starts as busy as 2012 ended. New people joined the lab and we have to finish many projects that yielded great result. About this soon more, here.
Now that the semester has ended, the conference season starts again and we will show our work. So far the following meetings are on our schedule, a few others may be added.
Annual meeting of the Condensed Matter Section of the German Physical Society.
Our Contribution has been selected to compete for the Gerhard-Ertl-Young Investigator Award. Even if I do not get it, it is a great honor to be one of the five to present there.
Controlling the Conformation of Peptides and Proteins on Solid Surfaces in Ultrahigh Vacuum
further there will be one talk
The molecular structure of a nine amino acid peptide at metal surfaces in vacuum
and two posters from our group
Organic molecular ion beam epitaxy of non-volatile molecules
Fully Controlled, High Flux Electrospray Ion Beam Deposition of Nonvoaltile Molecules in Vacuum
ISSC meeting, Nottingham
Interdisciplinary Surface Science Conference
a workshop of the german ion beam community
I cant remember. I have this Google account which I use for Email and Calenders and-rarely-also I look up something in Google Scholar. Obviously that part o Google was improved to contain author lists and citation metrics and I have to say, that I am impressed. Take a look: S. Rauschenbach Google Scholar Page.
Maybe I created this profile a while ago and forgot about it again. Anyhow, it is a bit scary, but also it work very well and looks good. And it seems useful too and is for free. (Is is really? This is about the question who is the customer of Google. Its not the users and my wife is getting ads for Brukers new AFMs… but this is a different story which belongs somewhere else.)
For a while we have been measuring and getting nice results. This year we could present ES-IBD plenty on conferences. Here is the summary:
– Material Research Society (MRS) spring meeting: talks by G. Rinke, C. Kley, S. Rauschenbach. poster by S. Rauschenbach
– International Conference on Nanotechnology (ICN+T) Paris: talk and poster by S. Rauschenbach
– International Material Research Congress (IMRC) invited talk by S. Rauschenbach
– International Mass Spectrometry Conference (IMSC): talk by S. Rauschenbach, poster by M. Pauly
Looking at our new data, there is hope that we will be traveling again next year. Certainly not all conferences provided the right audience for our work. But we certainly will go again to the ICN+T and the IMSC, since they are excellent meetings of very high quality, focused on the thing we do: that mix of mass spectrometry and surface science.
In electrospray ion beam deposition one naturally cares a lot about mass spectrometry as this is where the technique originated from. Today I looked into mass spectrometry societies around the world and made a list in the links section.