[TheForge] plastic forge? OT:

[Bruce Freeman]

I'd guess that graphene is transparent because it 's one-atom thick.
That thicknes probably absorbs as much, if not disproportionately
more, light as graphite -- but it's too thin to make much of a
difference in transmittance.

As for gases, actually when they do "conduct", they do emit light.
But their "conduction" involves their ionization by a spark, which is
just promotion of an electron "to infinity", and the light emission
occurs when the electron is recaptured by an ion.  Happens all the
time in a neon lamp, or in the UV in a fluorescent lamp (which emits
visible light only by the "conversion" of UV to visible light by the
fluor.

On Thu, Jun 16, 2011 at 3:24 PM, CraigSchaefer <calvinjean2 at comcast.net> wrote:
>
>
> gasses?
>
>
>
>
> ----- Original Message -----
> From: "Bruce Freeman" <freemab222 at gmail.com>
> To: "Blacksmithing List Sponsored by ABANA" <theforge at mailman.qth.net>
> Sent: Thursday, June 16, 2011 9:48:02 AM
> Subject: Re: [TheForge] plastic forge? OT:
>
> Free electrons are involved in the absorption of light due to the fact
> that a photon of light will "promote" an electron from a lower- to a
> higher-energy state.  In pure elements, this is what gives rise to the
> absorbance spectra of the element (hydrogen, for example).  It is also
> the case for molecules.  The more possible energy states available for
> an electron to "reside" in, the more different possible transitions
> possible.  A photon of a particular energy corresponds to a 'color'.
>
> I don't see how running a current through a transparent material would
> have anything to do with color.  Salt water conducting electricity
> remains clear, but then electrons don't run through salt water -- ions
> do.  I would suppose it unusual for a transparent material to be able
> to conduct electricity.  Can you think of one?
>
> On Thu, Jun 16, 2011 at 12:38 PM, peter fels <artgawk at thegrid.net> wrote:
>>
>>>
>>>
>>>
>>> As you probably know, diamond is crystalline carbon, in which each
>>> atom is connected to four others in a tetrahedral configuration (i.e.,
>>> the OTHER four carbons are at the corners of a tetrahedron).  Very
>>> strong, very hard, no free electrons so completely transparent.
>>>
>>> By contrast, graphite is crystalline carbon, in which each atom is
>>> connected to only three others in a hexagonal array (i.e., honeycomb
>>> or chickenwire shape).  This is even stronger than diamond within the
>>> plane.  However, the myriad of layers of carbon are only held together
>>> by their electronic interaction and whatever stuff that attracts to
>>> between the planes.  There are LOTS of loose electrons floating
>>> around, so virtually any wavelength of visible light can be absorbed,
>>> rendering the stuff black.
>>>
>>>>>> How fascinating.
>> Bruce, do you know why free electrons absorb light?
>> Does this mean that running a small current through or across a transparent  material will male it opaque?
>>>>>>
>>>>>>>
>>>>>>>
>>
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>
>
>
> --
> Bruce
> NJ
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-- 
Bruce
NJ