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Chris Spicer @ RealScientists Nano

15 Nov, 15 tweets, 3 min read

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?

3. What do you call an atom whose electrons have reached a higher energy state?

4. When an electron drops down from a higher energy state and recombines with a hole, what is produced?

5. Laser light has many features different to ordinary incandescent light. Which of these is NOT one of them?

6. What requirement needs to be met before a medium can begin to 'lase'?

7. What is the minimum number of energy levels needed for lasing?

8. The wavelength of the laser light depends on what feature of the medium?
a) The density of excited atoms
b) The energy gap between the excited and ground state
c) The amount of energy levels in the lasing process
d) It has nothing to do with the medium

9. What is NOT a form of laser?

10. In what decade was the first laser built?

And last but not least, because in the podcast I used some Astronomy/Cosmology fact to try to explain just how short an attosecond is, and I mentioned my interest in music... a fitting bonus questions:

🌟. Why is this song named after the asteroid number of Pluto?

I will come back later today with the solutions. But if don't want to wait until then... you can find them here, too:
funtrivia.com/playquiz/quiz2…

@coenneli

(thread by @coenneli)

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More from @RealSci_Nano

Chris Spicer @ RealScientists Nano

@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

Chris Spicer @ RealScientists Nano

@RealSci_Nano

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

Chris Spicer @ RealScientists Nano

@RealSci_Nano

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…)

Read 16 tweets

Chris Spicer @ RealScientists Nano

@RealSci_Nano

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

Chris Spicer @ RealScientists Nano

@RealSci_Nano

11 Nov

Good evening! While my fan heater is doing its job, why don't we catch some electrons?

https://twitter.com/RealSci_Nano/status/1326189495805505536?s=20

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).

https://twitter.com/RealSci_Nano/status/1326189495805505536?s=20

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.

Read 11 tweets

Chris Spicer @ RealScientists Nano

@RealSci_Nano

10 Nov

Hello everyone!
To talk about my research, I decided to theme it by "studying the ionisation process itself" (today) and "possible things that can happen afterwards" (tomorrow).

I'm going to keep the explanations in the threads fairly colloquial. But I will link the corresponding publications (open access whenever possible) so you can dig into the details there if you wish. Or of course, just ask me any questions you might have and I'll expand on that 😉

Yesterday I have already introduced the idea that the strong electric field of the laser pulse modifies the Coulomb potential which keeps electrons in bound states. The video shows a classical picture of this: