High School How much rubidium-88 is there in nature?

[Rev. Cheeseman]

I tried to find the ratio of rb88/rb87 but can't find any. What are the ratio of rb88/rb87 in nature?

 

[Frabjous]

Rb88 has a half life of ~18 minutes, so effectively 0.

 

[Rev. Cheeseman]

Rb88 has a half life of ~18 minutes, so effectively 0.

The natural abundance of Francium 223 and Oxygen 15 are trace. In comparison with Francium 223 or Oxygen 15, are both trace?

 

[fresh_42]

https://de.wikipedia.org/wiki/Rubidium

 

[Rev. Cheeseman]

View attachment 358648

https://de.wikipedia.org/wiki/Rubidium

In English wikipedia, it is just blank. Confusing.

 

[fresh_42]

Here are alternatives:

https://www.nndc.bnl.gov/nudat3/
https://www.periodensystem-online.de/index.php?el=37&id=isotope&sel=

but I haven't checked out all of the chemistry links listed here:
https://www.physicsforums.com/threa...h-physics-earth-and-other-curiosities.970262/

 

[Rev. Cheeseman]

Here are alternatives:

https://www.nndc.bnl.gov/nudat3/
https://www.periodensystem-online.de/index.php?el=37&id=isotope&sel=

but I haven't checked out all of the chemistry links listed here:
https://www.physicsforums.com/threa...h-physics-earth-and-other-curiosities.970262/

According to https://www.osti.gov/servlets/purl/1414348, it was stated 'Nevertheless, at high neutron densities, up to 54 % of the total 85Kr captures a neutron, generating 86Kr, eventually leading to an enrichment of 88Sr (Fig. 5). However, at least 46 % of the 85Kr decays to 85Rb, which could lead, via 86Rb (~19 d half-life), to 86Sr. Again, at high neutron densities, 87Rb is produced, eventually leading to an enrichment of 88Sr (Fig. 5). The decay of 87Rb has been ignored in these considerations. With its half-life of ~49 Ga, it can be treated as stable here, although at temperatures >5×108 K, the half-life drops below 105 a (Takahashi and Yokoi, 1987). But even at such temperatures, decay of 87Rb would still play a very minor role at neutron densities >107 cm–3 (cf. Fig. 6). Furthermore, the refractory element strontium and the volatile element rubidium should be highly fractionated during SiC grain condensation (Lugaro et al., 2003; Liu et al., 2015), leaving the grain relatively depleted in rubidium. Therefore, any contribution of decaying rubidium to strontium isotopes after grain formation is negligible.' from pg. 14 - 15.

In order for rubidium 87 to become strontium 88 they have to become rubidium 88 first. No? So, are rubidium 88 trace?

 

[pbuk]

In English wikipedia, it is just blank.

No it isn't

 

[Rev. Cheeseman]

No it isn't

View attachment 358659

88rb wasn't there

 

[Baluncore]

88Rb is missing from: https://en.wikipedia.org/wiki/Rubidium
But it is present here: https://de.wikipedia.org/wiki/Rubidium

 

[pbuk]

88Rb is missing from: https://en.wikipedia.org/wiki/Rubidium
But it is present here: https://de.wikipedia.org/wiki/Rubidium

Oh I see. These tables only list the principal isotopes, a longer list can easily be found (e.g. by searching the interweb for "rubidium 88") at https://en.wikipedia.org/wiki/Isotopes_of_rubidium.

The natural abundance of Francium 223 and Oxygen 15 are trace. In comparison with Francium 223 or Oxygen 15, are both trace?

²³⁵Fr exists in nature as it is a product of the decay chain of naturally occuring ²³⁵U. As it has a half-life of 22 minutes it is not practical to quantify its abundance, however because it is not nil we give it the qualitative value of "trace".

¹⁵O exists in nature as it is a product of gamma-bombardment of ¹⁶O. As it has a half-life of just over 2 minutes it is not practical to quantify its abundance, however because it is not nil we give it the qualitative value of "trace".

There is no natural process (on the Earth) that produces ⁸⁸Rb and so we quantify its abundance as nil.

 

[pbuk]

Do not start more than one thread on the same topic - this has been reported.

are rubidium 88 trace?

That is not a well-formed question. If you mean "does Rubidium-88 have trace abundance?" then the answer is no: its abundance is nil. This is because the high neutron densities that are required to start the process producing ⁸⁸Rb do not naturally occur on Earth.

 

[Rev. Cheeseman]

Do not start more than one thread on the same topic - this has been reported.


That is not a well-formed question. If you mean "does Rubidium-88 a trace have a trace abundance?" then the answer is no: its abundance is nil. This is because the high neutron densities that are required to start the process producing ⁸⁸Rb do not naturally occur on Earth.

So, that usually happens outside the Earth then. Sorry, it is not me who moved this question into a new thread. I believe it is a mod who did that as I received a notification that this question was moved into a new thread.

 

[Rev. Cheeseman]

Oh I see. These tables only list the principal isotopes, a longer list can easily be found (e.g. by searching the interweb for "rubidium 88") at https://en.wikipedia.org/wiki/Isotopes_of_rubidium.


²³⁵Fr exists in nature as it is a product of the decay chain of naturally occuring ²³⁵U. As it has a half-life of 22 minutes it is not practical to quantify its abundance, however because it is not nil we give it the qualitative value of "trace".

¹⁵O exists in nature as it is a product of gamma-bombardment of ¹⁶O. As it has a half-life of just over 2 minutes it is not practical to quantify its abundance, however because it is not nil we give it the qualitative value of "trace".

There is no natural process (on the Earth) that produces ⁸⁸Rb and so we quantify its abundance as nil.

Therefore, that usually happens outside the Earth then.

 

[berkeman]

Do not start more than one thread on the same topic - this has been reported.

Sorry, it is not me who moved this question into a new thread. I believe it is a mod who did that as I received a notification that this question was moved into a new thread.

Yes, it was a Mentor who broke this off as a new thread; it is not a duplicate.

 

[snorkack]

Do not start more than one thread on the same topic - this has been reported.


That is not a well-formed question. If you mean "does Rubidium-88 a trace have a trace abundance?" then the answer is no: its abundance is nil. This is because the high neutron densities that are required to start the process producing ⁸⁸Rb do not naturally occur on Earth.

The r-process does not occur naturally on Earth.
The trace concentration of Rb-88 is not nil, but there is a bigger problem why it does not concentrate in minerals.
Short half-life. Under 18 minutes.
Whatever mechanism forms Rb-88:

1. r-process, off Earth
2. s-process, including capture of a single neutron from fission or cosmic rays by the long-lived and common Rb-88
3. spallation by cosmic rays
4. fission

it decays quickly. And only 2) forms Rb-88 in context proper for Rb.

 

[pbuk]

Therefore, that usually happens outside the Earth then.

When we talk about relative abundance of an isotope we are talking about relative abundance on Earth: what may or may not happen in the core of a star is not relevant.

 

[Rev. Cheeseman]

The r-process does not occur naturally on Earth.
The trace concentration of Rb-88 is not nil, but there is a bigger problem why it does not concentrate in minerals.
Short half-life. Under 18 minutes.
Whatever mechanism forms Rb-88:

1. r-process, off Earth
2. s-process, including capture of a single neutron from fission or cosmic rays by the long-lived and common Rb-88
3. spallation by cosmic rays
4. fission

it decays quickly. And only 2) forms Rb-88 in context proper for Rb.

Thank you. R process stand for rapid process and s process is slow, is not it? I can't remember exactly

 

[snorkack]

Thank you. R process stand for rapid process and s process is slow, is not it? I can't remember exactly

Yes.
Unlike r-process, which cannot happen on Earth, s-process happens in trace amounts - spontaneous fission, cosmic rays and α,n reactions produce trace amounts of neutrons. ¹⁴C is a s-process nucleus and famously has a natural background level.
Unfortunately the thread is cut out of context which makes it hard to tell what is relevant to the original question.

 

[snorkack]

Looked up the other thread, and it does not make the issue moot...
Look at the Wikipedia article...
https://en.wikipedia.org/wiki/Delayed_neutron
It just... jumps to "groups"? Without any attempt of explanation why these are "groups"! Or why 6 vs. 8.
This
https://ec.europa.eu/programmes/era..._part_2_Experiment_procedure_for_students.pdf
at least gives the reason.
Remember: delayed neutrons do NOT come from "groups"! Every delayed neutron is emitted from a specific radioactive fission product which has its own yield, branching ratios, decay energies...
https://www-nds.iaea.org/relnsd/delayedn/delayedn.html
But about isotope lists, see:
https://en.wikipedia.org/wiki/Isotopes_of_krypton#List_of_isotopes
Kr isotopes 85, 86, 89 and 92 are marked as "fission products", but 87, 88, 90 and 91 are not.
Why, do you guess?
Are they provably absent in fission fragments to adequate precision?
Or did Wikipedia editors neglect to add the notes to these isotopes?
Or did people working on fission not bother to measure their yields and publicize their results?
The half-lives of these isotopes are 76 and 170 minutes and 32 and 8 seconds. They contribute some to delayed heat (but so do many other fission products) but do not emit delayed neutrons.
This makes me wondering about Rb-88.
Is absence of its fission yield a confirmed fact or mere oversight?
Because if it actually does have a fission yield, it will be present as a trace product of natural spontaneous fission.

 

[Rev. Cheeseman]

Looked up the other thread, and it does not make the issue moot...
Look at the Wikipedia article...
https://en.wikipedia.org/wiki/Delayed_neutron
It just... jumps to "groups"? Without any attempt of explanation why these are "groups"! Or why 6 vs. 8.
This
https://ec.europa.eu/programmes/era..._part_2_Experiment_procedure_for_students.pdf
at least gives the reason.
Remember: delayed neutrons do NOT come from "groups"! Every delayed neutron is emitted from a specific radioactive fission product which has its own yield, branching ratios, decay energies...
https://www-nds.iaea.org/relnsd/delayedn/delayedn.html
But about isotope lists, see:
https://en.wikipedia.org/wiki/Isotopes_of_krypton#List_of_isotopes
Kr isotopes 85, 86, 89 and 92 are marked as "fission products", but 87, 88, 90 and 91 are not.
Why, do you guess?
Are they provably absent in fission fragments to adequate precision?
Or did Wikipedia editors neglect to add the notes to these isotopes?
Or did people working on fission not bother to measure their yields and publicize their results?
The half-lives of these isotopes are 76 and 170 minutes and 32 and 8 seconds. They contribute some to delayed heat (but so do many other fission products) but do not emit delayed neutrons.
This makes me wondering about Rb-88.
Is absence of its fission yield a confirmed fact or mere oversight?
Because if it actually does have a fission yield, it will be present as a trace product of natural spontaneous fission.

Therefore, 88rb is trace in natural abundance or?

 

[Rev. Cheeseman]

s-process, including capture of a single neutron from fission or cosmic rays by the long-lived and common Rb-88

Sorry, do you mean Rb-87

 

[snorkack]

Sorry, do you mean Rb-87

Sorry, yes. Rb-87+n.

 

[Rev. Cheeseman]

The r-process does not occur naturally on Earth.
The trace concentration of Rb-88 is not nil, but there is a bigger problem why it does not concentrate in minerals.
Short half-life. Under 18 minutes.
Whatever mechanism forms Rb-88:

1. r-process, off Earth
2. s-process, including capture of a single neutron from fission or cosmic rays by the long-lived and common Rb-88
3. spallation by cosmic rays
4. fission

it decays quickly. And only 2) forms Rb-88 in context proper for Rb.

Is this correct? Rapid processes at outer space happen , for example, when a neutron ray hit those asteroid belts and then some elements capture those neutrons and change into different isotopes. While slow processes happen on Earth by the same radiation that is produced during thunderstorms hitting the 87Rb on Earth and then change these 87Rb into 88Rb. How long does it take for the whole 87Rb to change to 88Rb during r-process and s-process?

 

[snorkack]

Is this correct?

No.

Rapid processes at outer space happen , for example, when a neutron ray hit those asteroid belts and then some elements capture those neutrons and change into different isotopes.

No.
Any single neutron capture event is "rapid" as in yoctosecond range, but "rapid process" means that there are so many neutrons that several of them are captured in a short timeframe - below years.

While slow processes happen on Earth by the same radiation that is produced during thunderstorms hitting the 87Rb on Earth and then change these 87Rb into 88Rb.

Insignificant amount.
The three major sources of neutrons on Earth are spontaneous fission, α,n reactions and cosmic rays. Not sure how their sizes compare.

How long does it take for the whole 87Rb to change to 88Rb during r-process and s-process?

It does not, in either.
Not in s-process, because with 18 minute half-life 88Rb decays to 88Sr.
Not on r-process, because 88Rb captures another neutron to become 89Rb, etc.

 

[Rev. Cheeseman]

No.

No.
Any single neutron capture event is "rapid" as in yoctosecond range, but "rapid process" means that there are so many neutrons that several of them are captured in a short timeframe - below years.

Insignificant amount.
The three major sources of neutrons on Earth are spontaneous fission, α,n reactions and cosmic rays. Not sure how their sizes compare.

It does not, in either.
Not in s-process, because with 18 minute half-life 88Rb decays to 88Sr.
Not on r-process, because 88Rb captures another neutron to become 89Rb, etc.

Thank you. If rapid processes happen below years, what about slow processes? Sorry, English is not my native language

 

[snorkack]

Thank you. If rapid processes happen below years, what about slow processes? Sorry, English is not my native language

https://en.wikipedia.org/wiki/S-process

In contrast to the r-process which is believed to occur over time scales of seconds in explosive environments, the s-process is believed to occur over time scales of thousands of years, passing decades between neutron captures.

 

[Rev. Cheeseman]

Not in s-process, because with 18 minute half-life 88Rb decays to 88Sr.

So the moment an amount of 87Rb are exposed to neutron radiation they immediately become 88Rb which in turn become 88Sr after around 18 minutes? Those 87Rb don't need minutes or hours to become 88Rb if they are exposed to neutron rays?

 

[snorkack]

Found a source, and Rb-88 is indeed a fission product:
https://www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html
No data for SF (harder to get) but they yields are unlikely to be zeroes.
How far are SF yields likely to be from the thermal ones? Because that is one contributor to specify the trace.

 

[Rev. Cheeseman]

Found a source, and Rb-88 is indeed a fission product:
https://www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html
No data for SF (harder to get) but they yields are unlikely to be zeroes.
How far are SF yields likely to be from the thermal ones? Because that is one contributor to specify the trace.

Sorry, what is SF? I think F stand for fission but what is S? Those 87Rb don't need minutes or hours to become 88Rb if they are exposed to neutron rays?