Re: Fluorescent Spectrum - Spikes vs Broad Slopes

"Victor Roberts" <xxx@xxxxxxxxxxxxxxxxxxxxx> wrote in message
news:v7jc025acku2rhf07dikeqgt4oo64ra7dt@xxxxxxxxxx

On Wed, 01 Mar 2006 20:35:14 -0500, Victor Roberts
<xxx@xxxxxxxxxxxxxxxxxxxxx> wrote:

Let's see how may typos I made in this :-)

Well, what I left out is that while the density of 6^3P1
atoms in a high pressure mercury lamp is determined mostly
by the local temperature, the work of Karabourniotis shows
that the density of this state is not fully in equilibrium
with the local temperature. Therefore absorption of 254 nm
photons can increase the density of the state. However,
this departure from LTE is so slight that most of the
absorption of Hg visible lines you see in your measurements
is controlled by the temperature profile of the discharge
and not 254 nm photon absorption.

Thanks. If I am to repeat the gist of what you wrote, you are saying that in
a (non LTE) low pressure mercury discharge, any self-absorption that appears
is controlled solely by absorption of 254nm photons, while in a (near LTE)
high pressure mercury discharge, self-absorption has little to do with
absorption of 254nm photons.

Therefore, if I was to measure the lines of a lpm discharge at high
resolution using a suitable device (such as a Fabry-Perot etalon), like on
the references for the 254nm line given above, any self-absorption I would
see would come from the absorption of 254nm photons, even on other lines,
while on my photos it indeed comes from the cooler gas around the tube
walls.

As an aside, the explanation I got for the Fraunhoffer absorption on the
tube walls on the high pressure discharges on my web page, came from physics
professor Howard Goldberg of the University of Illinois, when I was a senior
there.

Thanks again for the detailed explanation,

--
Vic Roberts
http://www.RobertsResearchInc.com
--
Ioannis --- http://ioannis.virtualcomposer2000.com/

.