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Beryllium 10 on Titan?
ngunn
post Nov 11 2011, 09:21 PM
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Like Earth, Titan is a world with many active processes operating, no doubt, over a wide range of timescales. In such an environment anything that can act as an absolute time marker in the landscape has the potential to yield a rich store of information. In an eye-opening paper* now a decade old Lorenz et. al. lay out this potential in respect of radiocarbon. They point out that not only will C14 be produced by the action of cosmic rays on Titan’s atmosphere but Titan has, in the formation of solid haze particles, a mechanism for removing it from the air and depositing it on the surface in solid or liquid form. Indeed Titan is probably the only place in the Solar System other than Earth where such a mechanism operates and where, as a consequence, there is the potential to use radiocarbon to track and date active processes in the landscape. The timescale involved is from centuries to a few tens of millennia, commensurate with the half-life of C14.

Well, there is another radioactive species produced by the action of cosmic rays on atmospheric nitrogen, namely beryllium 10. It has a much longer half-life, around 1.3 million years, which could make it the perfect complement to C14 by taking over the role of landscape marker for timescales in the range 10^5 t 10^7 yr. On Earth it is used as a tool for studying palaeoclimate. My (inexpert) searches have not turned up any references to Be10 on Titan so I thought I’d post my questions here. I’ve read enough to be sure that Be10 must form in Titan’s atmosphere, just like C14, so my questions are:

1/ Are there papers out there that I haven’t found where this is mentioned or discussed?

2/ If not, has anybody heard it raised informally, at a conference or whatever?

3/ What would likely happen to the Be 10 once formed? How would it react chemically? Would it be incorporated into haze particles or other precipitation and thereby end up in lakes and sediments?

* http://www.google.co.uk/url?sa=t&rct=j...VCg&cad=rja
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Juramike
post Nov 11 2011, 10:18 PM
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I would assume that the berylium would drift down in the atomspheric fallout and exist as isolated atoms in a matrix or organics.

Would it be mobile (soluble) and leach out of the matrix? Probably not.

Beryllium itself likely would not dissolve in organic solvents. Beryllium is also pretty oxophilic, so if it did manage to react with water/ice it would convert over to the oxide form BeO (releasing one molecule of H2), which should be also pretty insoluble in organic solvents. [Beryllium metal is not reactive with oxygen at room temperatures, but it might be due to an thin oxide coating - when dealing with a single isolated atom I'd assume oxidation happens] Beryllium can also form a cation in water [Be(H2O)4]2+

At high temperatures (maybe in rarefied environments in upper atmosphere?) beryllium can react with nitrogen to make the nitride Be3N2 (readily hydrolyzed by water, but we'll assume that doesn't happen). It can also react with ethylene at high temperatures to form BeC2 (+ 2
H2).

The solubilities of the Be compounds is pretty poor in organic solvents, even though the bonds have predominantly covalent character. (Cotton and Wilkinson 3rd ed.)

Link to article with solubility data (starting on p.8): http://ntp.niehs.nih.gov/ntp/newhomeroc/roc10/be.pdf

So yeah, it's a good idea, any beryllium atoms that drift to the surface and get stuck in layers should stay there and be a great marker, unless there was some type of aqueous event, like an impact melt pool or something.


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ngunn
post Nov 11 2011, 11:01 PM
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Thanks Mike. I'm all at sea when it comes to chemistry so grateful for your input.

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rlorenz
post Dec 30 2011, 02:37 PM
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QUOTE (ngunn @ Nov 11 2011, 04:21 PM) *
eye-opening paper* now a decade old Lorenz et. al. lay out this potential in respect of radiocarbon......


you're too kind. It was actually Tim Swindle's idea originally (and you only need to say 'radiocarbon
on Titan' to convey the whole concept, which is kinda cool in this specialized day and age) , I did
the legwork to figure out how much there might be, what would happen to it etc.


QUOTE
the potential to use radiocarbon to track and date active processes in the landscape......
another radioactive species produced by the action of cosmic rays on atmospheric nitrogen, namely beryllium 10.

1/ Are there papers out there that I havenít found where this is mentioned or discussed?

2/ If not, has anybody heard it raised informally, at a conference or whatever?

3/ What would likely happen to the Be 10 once formed? How would it react chemically? Would it be incorporated into haze particles or other precipitation and thereby end up in lakes and sediments?


Well, I don't know what you havent found, but I have some familiarity with the literature and
am not aware of this being mentioned anywhere to date, even informally (although it is a logical
extension of the radiocarbon idea). I believe I have heard 10Be mentioned in the context of
ice cores on Mars, though.

I'd imagine as you say the Be would get deposited on Titan's surface somehow via the haze.

That said, it's a rather academic proposition. 14C could be concentrated enough on Titan to detect
with a geiger counter. But 10Be is a vary rare atom - I think you stick rock samples in Earth analyses in a
room-sized accelerator mass spectrometer (you need very high sensitivity to count rare atoms, and very
high mass resolution to not count isowhatsits). We're not going to fly one of those to Titan any time soon.

sorry for the slow response - day job has been all-consuming of late....
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ngunn
post Jan 1 2012, 11:15 PM
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Great response - thanks - and not slow at all. I'll wait in the real slow lane for the necessary machine to arrive on Titan.
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PFK
post Jan 6 2012, 12:10 PM
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QUOTE (Juramike @ Nov 11 2011, 10:18 PM) *
I would assume that the berylium would drift down in the atomspheric fallout and exist as isolated atoms in a matrix or organics.

Interesting question isn't it, because you're generating it literally one atom at a time. So determining "reactivity" would be tough - there have been studies on the reactivity of laser ablated Be atoms with methane:
e.g. T.M Greene, D.V Lanzisera, L Andrews and A.J Downs. J. Am. Chem. Soc., 120 (1998), p. 6097
"Beryllium atoms produced by laser ablation have been co-condensed with methane/argon mixtures onto a substrate at 10 K. Infrared spectroscopy has been used to identify a number of organoberyllium products, viz. CH3BeH, CH3BeCH3, CH3Be, H2CBeH, and HCBeH. "

As an aside, it's always one of the more nerve wracking times in a lab when someone else in there is using Be compounds. They're not the nicest - in fact Guinness used to note Be as being the most toxic non radioactive element. Nature is at its slyest, therefore, when it plays the trick of making Be compounds taste sweet! Mind you, I've only ever known one person test that!
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Juramike
post Jan 6 2012, 05:34 PM
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QUOTE
Mind you, I've only ever known one person test that!


I've heard it said that nobody knows what Nickle tetracarbonyl smells like.


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PFK
post Jan 6 2012, 09:42 PM
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QUOTE (Juramike @ Jan 6 2012, 05:34 PM) *
I've heard it said that nobody knows what Nickle tetracarbonyl smells like.

Ah yes, even when we did a fair bit of carbonyl work many moons ago I gave that one a miss rolleyes.gif
Dennis Evans, inventor of the Evans Balance (http://en.wikipedia.org/wiki/Evans_balance) back in my time at IC was the only person I knew who confirmed the beryllium taste. But then Dennis was Old School; for example during an UG tutorial he illustrated the toxicity level of KCN by dipping his finger in a pot of it and showing that as you need 0.25g to kill yourself, you can happily taste a small amount. Needless to say non of us took him up on the offer; I did however avail myself of his demonstration of how to "gargle" liquid nitrogen (you keep it moving!) though I baulked at reproducing his party piece of doing it with liquid oxygen and then blowing out through a cigarette! While I was postdoc there he was admonished for smoking while demonstrating in the teaching lab; his response was to demonstrate how to stub your cig out in ether (you just have to be quick!). Around the same time I did have a Be encounter when breaking up the tedium between reactions by organising a game of football in the corridor (as you do). As goalposts we used two big boxes of materials from an old store that were being disposed of. After rattling the post a few times it occurred to me I'd better just check what was in the boxes just in case we broke them; finding two 100g jars of beryllium sulfate put a stop to the game pretty quickly biggrin.gif
Health and Safety aint no fun smile.gif
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