On a related theme, can you guess what this is?

No, but something in me says "I want to have a play with that!"

Quote from: SteveF

Sorry taking with phone and no software to resize it on this machine...

Not even paint?

Anyways did a bit of editing for ya and now its clicky so the original is still available

Cheers, nope not even paint at the time... I was using a small linux distribution attached to the machine in question and they get a little edgy about people installing software on the control machines.  Could have fixed it since but forgot

Its one of the small XPS machine with some STM stuff in there in one of the side bunkers at Daresbury synchrotron lab.  The big metal cylinder at the back is the XPS giveaway in case you care.

What do you do, out of interest?

Research into molecular electronics and stoof.  Surface science of semiconductors, dna wires, chip fabrication, whatever Im asked to play with really.

Were trying to image molecules at the solid/liquid interface. Basically trying to get hydrocarbons to adsorb onto the surface of graphite and then image them, its proving pretty challenging. Weve got pretty good atomic resolution on the graphite substrate but the hydrocarbons are proving elusive.

Yeah theyre going to be tricky to see..  If you can you could maybe view them in cross section with something like TEM (transmission electron).  Contact/tapping mode AFM might be a slightly nicer alternative to STM if youre having problems as the equipment is pretty common in almost lab in the country.

Spreading the hydrocarbons Im guessing youre using a langmuir-blogett technique (dipping the graphite in a solution including hydrocarbons).  Ive just put in an application this afternoon to buy a contact angle meter which is a really simple but powerful tool which looks at the angle a drop of liquid forms on the surface of a material.  Its designed to measure exactly your type of layers and some similar things I work on.  It may be able to help you determine the layer thicknesses and how perfect the layer is on your surface is if its any use to you.

Ive done some bits and bobs on physically bonding hydrocarbons (specifically 1-alkenes) to semiconductor/metal surfaces over the years which may be a nice route to look at if you get time as you can make them without much effort...  The advantage of doing it that way is you get incredibly flat surfaces (compared to graphite) and you can prove the layers are there cheaply because the surface of the materials wont oxidise over time when you have a good layer, i.e. you can hydrogen terminate some silicon (111) in HF/NH4F (remove the oxide layer) then drop the chip in some 1-alkene chains and heat to about 160 degrees a layer forms.  If you then use your STM tip to scan the hydrogen terminated silicon it will start out showing the step and terrace structure of the silicon but then degrade to an oxide layer over time.  The alkyl monolayer one will stay looking like it was just raw silicon because the oxygen cant get to the surface.  Its a really elegant experiment.

At the end of the day XPS is the best technique but its a pain in the ass to get beam time at any facilities.  About the only good one you could use in this country is the one pictured above.  Reflected FTIR (infrared absorbtion) would also work but Im struggling to find a lab that has a system that can do reflection measurements and actually has the machine operational at the moment but there is a PEM-IRRAS system up here Im trying to make them connect up which may also be useful to you?


If you have know idea what some of these tools are yet just ignore the above or ask your supervisor but Im happy to help you measure stuff if Nottingham doesnt have a particular machine (or more likely they do but have no postgrads/RAs free to help you test things)...



Would be interested to see what exactly youre working on as this field is a very small community and if youre thinking of PhDs theres a good chance wed end up working on stuff mutually beneficial further down the line.  It never hurts to have a few more people/contacts you can bounce ideas off/share facilities

Is there *anything* really simple anymore? It all seems bloody complicated to me :/

I tried to keep it simple but the silly people who came before me named everything really complicated names and abbreviations.  Most things are really simple they just make it hard to get past the jargon.

In short, when water falls on a car bonnet it lays out into a big fat blob of water.  When you wax your car the water beads up and sits on the surface as little pellet type drops. (like drops of dew)


a hydrophilic (loves water) surface gives big blobs of water with a small angle that want to stick to the surface.


a hydrophobic (hates water) surface makes the water stand up and try and run off the surface.


If you know what water looks like when its on the car paint only and also know what its like on pure wax then you can work out some clever stuff about the surface.  If the water looks like it did on the car paint only then the layer is probably not there or its very thin.  At the other end of the scale when the wax is thick enough it may as well be sat on solid wax.  The shape of the drop will gradually change from one shape to another as the wax gets thicker or a better coverage.  By seeing how much it has changed you can work out how well the wax is covering the surface, how thick it is, how pure it is etc etc just by taking a closeup photo of the water drop.  Clever huh



Now change the car for a chunk of graphite and change the wax for his chemical and it still works on a tiny scale.  You can see whats on the surface or how clean it is just by looking at the water droplet and measuring the angle it touches the surface.  Most other techniques involve scratching a hole in the material (destroying it) then trying to measure the tiny height change which may only be a couple of atoms high on this scale.

This just involves putting a drop of water on it and does the same