On 30/09/2017 20:32, John Heath wrote:
[Moderator's note: Quoted text snipped. -P.H.]

I was having fun trying to come up with a spectrum analyzer that would
make a distinction between copper iron and gold. Clearly the motive was
financial gains rather than than science. In doing this research it
became apparent that the high Q spectrum lines of a gas were very
different from solids. The meaning of Q is the degree of well defined
spikes in the spectrum VS low Q soft spectrum that changes at a
disappointing slow rate. For example the difference between copper and
gold from red to blue is just a fluffy soft cure without any sharp
identifying spikes to say you hit pay dirt. A gas on the other hand such
as O H or N has high Q spikes in the infrared part of the spectrum
making identification easy. In short a gas liquid and solid are very
different when it comes to their absorption and reflective spectrum.

You don't do it at optical wavelengths...

There is a simple way to do metals with X-ray Fluorescence spectroscopy
which would work fairly well - Bruker hold some key XRF patents:

http://alloytester.com/xrf-technology

And it is handheld portable (other brands are available).

One of the applications is gold purity. The other way to do it would by
laser ablation mass spectrometry but they are not so portable.

--
Regards,
Martin Brown