Re: APOD: Hanny s Voorwerp (2011 Feb 10)
Posted: Fri Feb 11, 2011 6:03 pm
Can you provide a reference to such a tube - either for purchase or that someone built in a lab? If you have expertise in the topic area - I assume you have references. If it is trivial to make such a tube - and you have done it yourself - surely there is a paper or product somewhere.
Can you describe the physical process by which you excited the doubly ionized oxygen - and how you avoided collisional deexcitation in a small tube - when the lifetime of the forbidden transition is on the order of minutes?
Can you provide a pointer to an observatory that has an [OIII] discharge tube providing a reference spectrum line?
The [OIII] emission line was a puzzle since Huggins first observed it ("nebulium") spectroscopically in 1864 until it was theoretically matched to [OIII] in the late twenties. People had already been blasting gases in discharge tubes for some time and never seen that emission line - which is why it was a puzzle. I don't know any reference to creating it in the lab - though I did find mention of [OI] and a few other much shorter-lifetime and lower energy forbidden lines created in the lab. It is possible that with an exotic, non-equilibrium setup the emission could be generated - but I know of no one who has done it, or why they would want to.
There are lots of discharge tubes for purchase, and they are used for calibration in spectroscopic work - but I don't know any that output a forbidden line prominently. Some of the shorter lifetime and lower energy ones may appear in the spectrum - but the long ones like [OIII] are rather unlikely.
You can, of course, have oxygen glowing in a discharge tube - but it is emitting allowed transition lines that have very short lifetimes.
I think dslrs are great at perceptual color - that's why they sell so well and people use them so much. They may not be great for quantitative photometric work, though, but they are tuned to human perception of color - which is the topic here.
zloq
Can you describe the physical process by which you excited the doubly ionized oxygen - and how you avoided collisional deexcitation in a small tube - when the lifetime of the forbidden transition is on the order of minutes?
Can you provide a pointer to an observatory that has an [OIII] discharge tube providing a reference spectrum line?
The [OIII] emission line was a puzzle since Huggins first observed it ("nebulium") spectroscopically in 1864 until it was theoretically matched to [OIII] in the late twenties. People had already been blasting gases in discharge tubes for some time and never seen that emission line - which is why it was a puzzle. I don't know any reference to creating it in the lab - though I did find mention of [OI] and a few other much shorter-lifetime and lower energy forbidden lines created in the lab. It is possible that with an exotic, non-equilibrium setup the emission could be generated - but I know of no one who has done it, or why they would want to.
There are lots of discharge tubes for purchase, and they are used for calibration in spectroscopic work - but I don't know any that output a forbidden line prominently. Some of the shorter lifetime and lower energy ones may appear in the spectrum - but the long ones like [OIII] are rather unlikely.
You can, of course, have oxygen glowing in a discharge tube - but it is emitting allowed transition lines that have very short lifetimes.
I think dslrs are great at perceptual color - that's why they sell so well and people use them so much. They may not be great for quantitative photometric work, though, but they are tuned to human perception of color - which is the topic here.
zloq
