Re: A Riddle for Relativists.

HW@....(Dr. Henri Wilson) wrote in
news:f5bd24d2um2d6rbuoce5a7fsog391qekb0@xxxxxxx:

On Fri, 9 May 2008 11:57:54 +0000 (UTC), bz
<bz+spr@xxxxxxxxxxxxxxxxxxxx> wrote:

HW@....(Dr. Henri Wilson) wrote in
news:dl1724pgoka8lidag8i2s7ugo3a12j8rcr@xxxxxxx:



But you seem to have made the same mistake again. Maybe you did MEAN
atoms. In which case you are wrong rather than mistaken.

No I meant atom, here.
You know how flourescence works, I presume.

Not as much as I would like to 'know' but 'flourescense'[sic] has little
to do with resonant absorption and re-emission, which is what we have
been discussing.

[quote from http://www.crscientific.com/fluorescence.html]
"Fluorescence" refers to emission of light caused when a material
absorbs light (electromagnetic energy) of one wavelength and re-emits
light of another. [unquote]

It is actually a bit more complex than that.
The emission in fluorescence is ALWAYS at a longer wavelength, lower
energy, than the excitation.

Good you now see the problem
A little bit of energy is required to execute the transition.

...so the emitted photons will NOT have the same frequency (if any) as
those applied field (if any photons ar involved).

Fluorescence is only one of may phenomena involving energy absorption and
emission.

And NOT the best one to study when one seeks to build a better clock.

When the laser would match the wavelength of the neon absorption line,
the impedance of the RF driver circuit would be upset.
By detecting the 'reflected power' in an SWR bridge, we could tell
when we were 'on frequency' with the tunable laser. We were actually
interested in the waveform produced when we hit the plasma with a
pulse from the laser.

...but again, the frequency that was monitored was that of the RF
driver.

The technology that allows frequency counting at visible frequencies did
not exist in 1995. It does now.

We did monitor the wavelength aka energy of the light.

You are very confused Bob. Wavelength is not 'energy'.

I am not confused. Perhaps I was not as clear as I should have been.
Ì assumed that you knew that energy is related to wavelength and to
frequency. If we know one of these, we know the other two.

We knew when our laser was 'on frequency' or 'had the right wavelength' or
'had the right energy' because it excited the neon gas atoms.
The conductivity of a neon lamp went up.

The etalon (a wavelength selective device that can be varied) and gratings
involved in tuning the laser were calibrated in wave-number.



We did NOT monitor the frequency of the RF driver. It was crystal
controlled. We were not interested in it. We just used it to produce a
plasma and to allow us to monitor the impedance of the discharge.

We were interested in how the impedance of the discharge itself changed
as the shock wave induced by the laser pulse traveled through the
plasma.

The lifetime of the excited states gave information about the ionization
states produced by the laser pulse. The waveform observed gave
information about the lifetime of the excited states.

Well, like I said, at no time were you actually counting cycles from
'photon frequency'.

As I said, the technology didn't exist at that time. However we DID have
the means to tune a light source to the 'frequency' we wanted.
Which was what you seemed to be saying was impossible.;

"Optogalvanic Transients in a Neon RF Discharge," J. Chem. Phys. 1994,
101,1959.
"Optogalvanic Effects as a Probe of Plasma Processes," J. Phys. Chem.,
1995 ,99,7530.






--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+spr@xxxxxxxxxxxxxxxxxxxx remove ch100-5 to avoid spam trap
.

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