Right, now, on to attoscience (which combines #quantum #physics with #ultrashort #lasers).
First, I dusted off an overview slide of my thesis presentation. Attoscience studies electron motion in bound states, ionization processes, charge transfer, and similar. Image
All of this happens on the time scale of attoseconds, 10⁻¹⁸ seconds (and sometimes femtoseconds = 10⁻¹⁵ s), which is almost unimaginably fast. In the short intro podcast with @the_ScienceTalk, I explained the comparison with the age of our universe.
To measure such fast dynamics we need an equally as fast tool, which is laser pulses of a few femtosecond duration or shorter. Because a lot of energy is compressed in a very short time, the peak power of these pulses can reach terawatts (similar to nuclear power plants). 😲☢️ Image
These high intensities of the electric field can then compete with the binding Coulomb force in atoms (and molecules, larger structures, ...) and not only mess with the energy levels, but also cause ionisations.
Now you might wonder, what on earth does that have to do with nanoscience? Well, in my personal research, I have exploited the interaction of nanostructures with the laser field to create various spatial structures in the electric field. But more on that later in the week.
Besides that, attoscience is concerned with understanding the dynamics of electrons in various materials, the field has started from studying atoms, to include molecules, surfaces, semiconductor structures, liquids…
You see where this is going? I talked a bit more about that in the @the_ScienceTalk podcast which will be released on Wednesday 🤗
(thread by @coenneli)

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More from @RealSci_Nano

15 Nov
Laser Quiz part 2: here come the solutions:
1. LASER = Light Amplification by Stimulated Emission of Radiation (a)
2. Electron
3. Excited state atom
4. A Photon (I don't think there is a lasing material capable of producing gamma range photons)
5. Diffuse
6. Population Inversion
7. 3 Levels (with just 2 levels, as one approaches population equality, stimulated emission and absorption would start balancing each other out, preventing population inversion and thus there is no amplification of the light)
8. b) The energy gap between excited and ground state
Read 7 tweets
15 Nov
Happy Sunday everyone!
It has been an adventurous week (in many ways 😁).
I recently came across this fun little #laser quiz and thought that would be a nice conclusion to my week here. So take a guess and play along 🤗
1. What does LASER stand for?
a) Light Amplification by Stimulated Emission of Radiation
b) Light Absorption by Simulated Emission of Radiation
c) Latent Absorption of Specified Elliptical Radons
d) Latent Amplification of Stimulated and Elliptical Radons
2. What particle plays the major role in the process of lasing?
Read 15 tweets
14 Nov
Hi everyone :-D
We have reached the weekend already. Over the last few days, I hope I managed to give you a small glimpse into my research field. But one promise I have not yet delivered on: Where will all of this lead? What's the point?
First of all, I don't think I have to convince you that the quantum tunnelling phenomenon is found in all kinds of fields. Recently I came across a paper discussing tunnelling times during a photosynthesis cycle in an organic molecule.
doi.org/10.1007/s13538…
Many might be familiar with Scanning Tunnelling Microscope (STM) technique to investigate surface structures with (sub-)atomic spatial resolution (or make an atomic stop-motion movie 😄)
Read 10 tweets
13 Nov
Hello again!
I have this itch to swing back to talking about physics after yesterdays more meta thread, much like a pendulum always striving towards the middle position, but constantly overshooting. BTW, pendulums are an excellent representation of how short laser pulses are created!
You have probably heard (or learned) that laser light has a very defined colour (one specific wavelength/frequency), and all photons are in phase with each other, all their waves are perfectly synchronised (coherent).
(Image source: miridiatech.com/news/2014/02/l…) Diagram of coherent vs Incoherent light
Read 16 tweets
12 Nov
It is evening again, and I finally find a moment to check in here. How are you doing?
I feel like my apartment has turned into a bit of a "sauna for beginners": higher room temperature than I would usually keep in wintertime, and more humid than usual in general (despite having open windows)...
I'm going to switch my plan around a bit. The exciting opportunities for future scientific and technological developments derived from #attoscience (and if I find the time, a project using nano-objects to modify the spatial dependence of my laser fields) will come later.
Read 19 tweets
11 Nov
Good evening! While my fan heater is doing its job, why don't we catch some electrons? Lasso
In yesterday's thread, the electrons which have been freed from their bound state by the laser mostly just oscillated around (steered by the electric field) and eventually flew off and away (until they hit a detector).
However, not all electrons are so lucky. For some of them, their trajectory ends up looking almost like that lasso up there. This is if their kinetic energy at the end of the laser pulse is not quite enough to escape from the Coulomb potential of the atom/ion. Image
Read 11 tweets

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