Scrutable

Boustrophedon wrote: ↑

Wed Jan 29, 2020 5:17 pm

It's a bit of a con, the strontium atom is effectively a very bright point light source, so OK you can see it but since the wavelength of light is much bigger that an atom it cannot be resolved: There could actually be two strontium atoms there and you couldn't tell.

I'm sure I saw a similar picture of a calcium atom in an ion trap like that years ago.

The field ion microscope can however resolve single atoms.

Boustrophedon wrote: ↑

Thu Jan 30, 2020 6:00 pm

Now I have a problem, in that my memory may be faulty, but we had one at school and it looked, in my memory, nothing like the hulking great cryogenically cooled versions to be seen on an image search. So I am confused.

The one at school looked like a big round bottomed chemistry flask with the inside of the bottom coated with phosphor and some electrical connections at the back. It was probably made by Philip Harris or one of the other concerns that made lab equipment for schools.
There was an elaborate rigmarole which involved high voltages possibly reversed to clean and etch the tungsten tip and then with a high voltage connected you got those pretty pictures as above. I remember it well because I was being a complete arse and trolling the teacher asking the teacher if they were not actually some sort of diffraction pattern.

The other part of the demonstration involved boiling off some other metal atoms from another electrode and you could see the individual atoms dancing around as moving dots on the image.

I ask because it was such a simple bit of kit and such a beautiful demonstration, but I can find no trace online of that particular piece of kit. Did anyone else see one or am I imagining it?

Boustrophedon wrote: ↑

Thu Jan 30, 2020 6:50 pm

It could have looked like that, there were several different tubes in that series. My memory is of it on a wooden stand?

JQH wrote: ↑

Fri Jan 31, 2020 1:43 pm

Never had wooden stands in my time working in schools (from 1983). It's possible Don's school had some really old kit.

JQH wrote: ↑

Fri Jan 31, 2020 1:43 pm

Never had wooden stands in my time working in schools (from 1983). It's possible Don's school had some really old kit.

Boustrophedon wrote: ↑

Thu Jan 30, 2020 6:00 pm

Now I have a problem, in that my memory may be faulty, but we had one at school and it looked, in my memory, nothing like the hulking great cryogenically cooled versions to be seen on an image search. So I am confused.

The one at school looked like a big round bottomed chemistry flask with the inside of the bottom coated with phosphor and some electrical connections at the back. It was probably made by Philip Harris or one of the other concerns that made lab equipment for schools.
There was an elaborate rigmarole which involved high voltages possibly reversed to clean and etch the tungsten tip and then with a high voltage connected you got those pretty pictures as above. I remember it well because I was being a complete arse and trolling the teacher asking the teacher if they were not actually some sort of diffraction pattern.

The other part of the demonstration involved boiling off some other metal atoms from another electrode and you could see the individual atoms dancing around as moving dots on the image.

I ask because it was such a simple bit of kit and such a beautiful demonstration, but I can find no trace online of that particular piece of kit. Did anyone else see one or am I imagining it?

Trinucleus wrote: ↑

Fri Jan 31, 2020 7:19 pm

Was about the size of an electron microscope.

Trinucleus wrote: ↑

Fri Jan 31, 2020 7:19 pm

The one I worked on was a very expensive looking collection of stainless steel piping and fancy electrical stuff to enhance the image. Was about the size of an electron microscope. Certainly the process of boiling off atoms until you got the pattern was how it ran.

I can vaguely remember some rudimentary set up with a glass flask which used the same principle which sounds like what you're thinking of?

Grumble wrote: ↑

Sat Feb 01, 2020 12:07 am

Trinucleus wrote: ↑

Fri Jan 31, 2020 7:19 pm

Was about the size of an electron microscope.

SEM or TEM or STEM? All very different sizes.

Boustrophedon wrote: ↑

Fri Jan 31, 2020 5:34 pm

JQH wrote: ↑

Fri Jan 31, 2020 1:43 pm

Never had wooden stands in my time working in schools (from 1983). It's possible Don's school had some really old kit.

Im talking 1970s here when I were a kid. School was 300 years old and the building dated from 1911, actually the science block was built in 63. There was some victorian stuff in there.

Gentleman Jim wrote: ↑

Mon Feb 03, 2020 9:44 am

Boustrophedon wrote: ↑

Fri Jan 31, 2020 5:34 pm

JQH wrote: ↑

Fri Jan 31, 2020 1:43 pm

Never had wooden stands in my time working in schools (from 1983). It's possible Don's school had some really old kit.

Im talking 1970s here when I were a kid. School was 300 years old and the building dated from 1911, actually the science block was built in 63. There was some victorian stuff in there.

Like, very "flame-proof", wooden retort stands and clamps?

Trinucleus wrote: ↑

Mon Feb 03, 2020 8:04 pm

And the asbestos mats.....

Gentleman Jim wrote: ↑

Tue Feb 04, 2020 8:40 am

Trinucleus wrote: ↑

Mon Feb 03, 2020 8:04 pm

And the asbestos mats.....

Not just the mats.
There was a big panic last summer, in some schools, when some of the gauzes that sit on top of the tripod, were found to contain very low levels of asbestos in the "ceramic" centre.
Cue 100's of schools (including this one), hurriedly disposing of all old gauzes, and ordering "certificated Asbestos-free" new ones - when any could be found with the panic buying