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A Nobel prize winner of the year 2000 (among other conductive polymers) in textbook and reality!

(source: Wikipedia)

It has a form of black powder, under the SEM one can see it either as long ribbons or clusters.

Images taken by the author, using Quanta SEM belonging to ICN.
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Cleanroom Spring/Summer Collection 2013

Today in Extreme Makeover: Cleanroom Edition, especially for the first day of the spring, we have Marianna (28 yo), a lab engineer. Marianna is bored with her usual style and looks for a new, fresh look that will suit her spring mood.

Stylist: This season green is definitely in. It's a great color for blondes, making pale skin and dark eyes more appealing. I went for Talla 2 style, which perfectly fits her frame. The look is completed with classic cleanroom boots. Some may say they are just a cheap Uggs imitation, but this is completely not true. This is a unique design, made of rubber and dust-free material. We gave a it a final touch with a flirty mask, a faint reminiscent of Venice carnival.

Marianna: I'm absolutely amazed! This is probably the best outfit I've ever worn. I would never expect that green all over will make such a good combination. And this mask... I'm loving it!

Before.. (are these boots from the past season?!)

And after! As they say stressed, depressed, but well dressed
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Thesis on-line

For anyone interested my humble thesis in now available online on Tesis Doctorals en Xarxa

I am not particularly proud of it, I'm sure there are various things that could have been done better, but i hope this may help some of you. At least to know which mistakes to avoid! :)
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Why 1D expands on cooling?

If we heat or cool an object we observe a change in its volume. This is due to the thermal expansion, and is described by the thermal expansion coefficient. It describes how the volume changes with temperature.
In the typical 3D solids if we heat up the size of the object will increase (easy!). That behavior is due to increasing of the energy. If we add energy to the system, the vibrations of the lattice atoms become more significant and the average distance between the atoms increases, which in the end contributes to the bigger volume/length of the system. As an easy example think of railway tracks getting deformed during hot, summer days.

Now the situation in 1D and 2D systems is totally different. Measurements were first done on graphene with SEM microscopy and Raman spectroscopy, both of them showing a negative thermal expansion coefficient. That means, that unlike the typical materials graphene contracts with increasing temperature. The negative thermal expansion coefficient was estimated to be rather large 8x 10^-6 1/K.

Then in our work we extracted the thermal expansion coefficient for single-walled carbon nanotubes. Because the nanotubes are so small, and the thermal expansion even smaller, we couldn't measure it directly. Instead we measured the shifts in resonance frequency of a nanotube resonator, which we then related to the change in tension of the nanotube. Taking into account the elongation imposed by contracting gold electrodes and substrate, we could determine the expansion coefficient of a nanotube. This is also negative and relatively large.

What is the reason behind negative thermal expansion of 1 and 2D objects?

This is a simple explanation offered by my ex-boss Adrian Bachtold. At 0 K temperature (so called absolute zero) there are no phonon modes in the sample, so you can imagine it laying completely flat on the surface, with a given length L0. Then if you increase the temperature there are more and more phononic modes, especially the flexural modes which are responsible for deforming the sample. If you then project the length on the sample LT on the surface it will appear shorter.
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Autumn art

We had a few rainy days here last week, clear sign that autumn is coming.
This is one of the autumn-style images, shades of grey and some golden leaves. It respresents a membrane partially destroyed during processing, but if you didn't know it looks like one of the images that can score a high price in Sotheby's!
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Holes and bubbles

Many things have changed recently, I've defended the thesis, went on long holidays, started a new job (http://www.icn.cat/~p2n/) and, well, here I am, back to the lab.
I am mainly working on nano/micro fabrication again, this time trying to develop some suspended SOI structures. There should be no trick in that, but of course something went wrong and the sample seems to be suffering from chicken pox :) We are wishing it a fast recovery!