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PostPosted: Fri Dec 04, 2009 11:47 pm 
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Brian wrote:
That is a good thing.... that way the smallest value wavelength is on the left side, just as you'd read the scale in a spectral graph..


I don't know why.. but whenever I think of light/spectra, my brain wants to order it on the basis of left-to-right being lowest-to-highest energy per quanta/photon... Irregardless of how many spectrophotometer knobs i've played with over the years.

Hey, thats a good question... I know you wouldn't be able to get the nice continuous graphs you share with us... but could I use an old spec20 spectrophotometer to measure transmittance and look for certain peaks/troughs in a spectra?! Would be a FANTASTIC way to get diagnostic spectral data without having to generate a whole bunch of unnecessary graph when doing ID!! (and I wont even have to wash any cuvettes :P)


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PostPosted: Sat Dec 05, 2009 12:42 am 
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thresh wrote:
but could I use an old spec20 spectrophotometer to measure transmittance and look for certain peaks/troughs in a spectra?! Would be a FANTASTIC way to get diagnostic spectral data without having to generate a whole bunch of unnecessary graph when doing ID!! (and I wont even have to wash any cuvettes :P)


OMG! Reading off transmission and writing it down by hand at each wavelength. Having to re-calibrate at each wavelength. And every time you pull the cuvette out for re-calibration, and put it back in, you'd have to be sure the gem was in the same location and orientation. This would have to be the most tedious method to collect a spectrum ever.

And I'm ok with plotting low to high energy in eV left-to-right, if the situation calls for it. But frequency and cm-1 scales, yuck, yuck, yuck.


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PostPosted: Sat Dec 05, 2009 4:26 am 
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cascaillou wrote:
Note that quartz used to be considered as trigonal but is is now considered as hexagonal.


Can you tell me by whom and why? (Of course I'm talking about alfa-quartz...)

cascaillou wrote:
This has been a debate between crystallographers for some time.


Oh, I know... :D


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PostPosted: Sat Dec 05, 2009 3:50 pm 
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Can you tell me by whom and why

I'm afraid I can't. However that's what I was teached a few month ago at gem classes (in France). I didn't discuss it more deeply as I just don't care much...lol


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PostPosted: Sun Dec 06, 2009 10:42 am 
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cascaillou wrote:
I didn't discuss it more deeply as I just don't care much...lol


Oh, I do. I have to, I guess. :P
http://www.springerlink.com/content/x2657u2227388lqt/

I was just curious if there was some new theory. Form time to time somebody in the past popped up with something new/strange. Thank you anyway.


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