Re: [Phys-L] quantum dots

[John Denker <jsd@av8n.com>]

On 04/10/2018 07:03 PM, Larry Smith wrote:

> One paragraph says “For this specific Quantum Dot kit, the sizes of
> each of the quantum dots are the _same_size_ in each vial, the main
> difference is due to the gradient concentration.  The nanocrystals
> have a ZnS outer shell with a CdSeS core.  As the density of one
> increases while the other decrease, the wavelength varies; however
> the overall diameter remains constant.”
>
> The next paragraph says “Using an LED close to 400 nm illuminate each
> vial so the class can see the emanations from each.  Explain to the
> class that the vials all contain the same solution; the only
> difference between them is the physical size of the quantum dots
> contained in each.”

The short answer is I can't figure it out.

I can however come up with a hypothesis that seems
plausible based on what they are trying to do, and
is consistent with some (albeit not all) of the
verbiage quoted above.

  Imagine a set of snow globes.  Each globe consists
  of a transparent envelope containing a non-transparent
  Santa.  All of the globes, i.e. all of the envelopes,
  have the same outside diameter.  The Santa-size varies
  from vial to vial, but within each vial it is uniform.

  They inconsistently use the term "quantum dot" to
  refer to the Santa and/or the entire globe.

No guarantees that this hypothesis is correct, but
it is something to consider.

====

The gobbledygook about "gradient concentration" has
to do with how the quantum dots are made;  google the
patents in the unlikely event that you care about this.

====================

Here is a possible source of information.  I quote from:
  https://www.youtube.com/watch?v=vVUF4JsJww0&t=102

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