2013: Conferences

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.

March 10th-15th

DPG meeting, Regensburg

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

 

March 24th-28th

ISSC meeting, Nottingham

Interdisciplinary Surface Science Conference

invited lecture

 

June 12th-14th

Ion Beam Meeting, Leipzig

a workshop of the german ion beam community

 

October 7th-11th

VEIT Summer School, Sozopol

 

Did I do something?

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.)

 

 

Conferences

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.

ICN+T

Many of our results are presented this year on the ICN+T 2012 conference in Paris (http://www.icnt2012.org/). I find the meeting very good, since it really focuses the surface science community in one place and can recommend it thus highly.

It is even more enjoyable, since Paris is such a lively city and the Sorbonne turns out to be an extraordinary meeting place.

MBE and Proteins

Two new works out this week. Both key works for our lab. In the first we show that the deposition of charged particle beams can in fact be equivalent to conventional molecular beam epitaxy.

see entry [13] on the publications page:
Crystalline Inverted Membrane Growth by Electrospray Ion Beam Deposition in Vacuum.
S. Rauschenbach, R. T. Weitz, N. Malinowski, N. Thontasen, Z. Deng, G. Rinke, G. Costantini, T. Lutz, P. Martins de Almeida Rollo, L. Harnau, K. Kern
Adv. Mater. 24 (2012), pg. 2761-2767

inverted membrane deposition

 

The second one is even nicer: We deposited proteins a while a ago and found so many things you can do with them in vacuum: deposit them folded and unfolded and refold them and in the end look at the single amino acid. Now we only need to find a way to know which amino acid you see.

see [14] on the publications page:
A Close Look at Proteins: Submolecular Resolution of Two- and Three-Dimensionally Folded Cytochrome c at Surfaces
Zhitao Deng, Nicha Thontasen, Nikola Malinowski, Gordon Rinke, Ludger Harnau, Stephan Rauschenbach, Klaus Kern
Nano Lett. 12 (2012) 2452–2458

Proteins on surfaces in UHV

electrospray ion beam deposition (ES-IBD) source (short version)

Our experiment consists of two parts: (1) the deposition source and (2) the tunneling microscope with the sample preparation.

Here I briefly introduce the deposition source, that we use to deposit nonvolatile molecules onto surfaces in ultrahigh vacuum (UHV). It is a differentially pumped apparatus consisting of six differential pumping stages starting at 0.1 mbar and reaching to 1e-11 mbar in the UHV deposition chamber.

Scheme of the ES-IBD setup

Fig. 1: Scheme of the ES-IBD setup

everything starts with the spray source (1) at ambient pressure. Sometimes we use curtain gas (2) to dry the droplets and help the electrospray desolvation. The ions enter the vacuum trough a capillay (3). In the first and second vacuum chamber they are bundeled by RF ion optics, one ion funnel (4) and one quadrupole (5). The next quadrupole (6) in in high vacuum, so no more collimation is possible, but we use it for mass selection. Further throughout the machine we use electrostatic lenses (7) to focus the beam through the apertures (8). We have a time-of-flight (TOF) mass spectrometer (9) to measure the chemical composition and then we can deposit: in high vacuum (10) for ex situ analysis, in a vacuum suitcase (11) to transfer the sample to another UHV instrument, and finally in UHV (12) to move the sample in our own STM.

More details in the future.

 

 

single molecular magnets probed individually

Electrospray ion beam deposition is also known under term soft landing. The softness of this approach was actually crucial in our work with molecular magnets:

S. Kahle, Z. Deng, N. Malinowski, C. Tonnoir, A. Forment-Aliaga, N. Thontasen, G. Rinke, D. Le, V. Turkowski, T. S. Rahman, S. Rauschenbach, M. Ternes, and K. Kern, “The Quantum Magnetism of Individual Manganese-12-Acetate Molecular Magnets Anchored at Surfaces.” Nano Lett. 12, 518-521 (2012), http://dx.doi.org/10.1021/nl204141z

The project was really tough: the molecule is fragile, only charged negatively, so we build a new TOF. Then we needed a UHV suitcase, we had a really crazy malfunction in the beginning. It took us several attempts to get the sample to the 1K STM. And then we saw much less features then we thought we would. Today we know that it has to be like this…

… and, there are two great things about this work:

First great thing: it worked! That was not straight forward. Manganese-12-Acetate is a notoriously unstable molecule. Even gold reacts with it, reducing the acetate ligands, which eventually causes the loss of the magnetic properties. With ES-IBD we could softly bring it to a surface and identify the individual molecules. You see the individual molecule in the first STM image (Fig. 1). Also films could be prepared nicely (Fig. 2).

Second great thing: A single Manganese12 moelcule is really a magnet. The guys at the 1K STM could actually find the signature of a high spin single entity. In the next image (Fig. 3) you see a typical tunneling spectrum. The two features – four, since its symmetric – correspond to a spin flip from S=10 to S=9 and an excitation of the spin angular momentum.

One more nice thing. The project was very ambitious and needed a lot of real experts, who in this case happen to be real nice people too and it was a real pleasure to work with them. Starting with synthetic chemists who can make such a molecule, we were able to deposit it intactly, our 1K STM guys could measure the spectra at such low energy and finally we got theory support from Florida.

… in the end this one was even featured by Nature Materials.

Abstract: The high intrinsic spin and long spin relaxation time of manganese-12-acetate (Mn12) makes it an archetypical single molecular magnet. While these characteristics have been measured on bulk samples, questions remain whether the magnetic properties replicate themselves in surface supported isolated molecules, a prerequisite for any application. Here we demonstrate that electrospray ion beam deposition facilitates grafting of intact Mn12 molecules on metal as well as ultrathin insulating surfaces enabling submolecular resolution imaging by scanning tunneling microscopy. Using scanning tunneling spectroscopy we detect spin excitations from the magnetic ground state of the molecule at an ultrathin boron nitride decoupling layer. Our results are supported by density functional theory based calculations and establish that individual Mn12 molecules retain their intrinsic spin on a well chosen solid support.

Keywords: Electrospray mass spectrometry; ion beam deposition; molecular magnetism; scanning tunneling microscopy; inelastic tunneling spectroscopy