Chemical Forums
Specialty Chemistry Forums => Nuclear Chemistry and Radiochemistry Forum => Topic started by: occam on May 20, 2008, 04:54:14 PM
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Beta decays of isotopes tend to form in chains, terminating in the stable atomic number.
Is there a similar trend in the spectral signature of the isotopes? i.e. a consistent blue or red shift with the decay progression?
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Graham:
I got the feeling you have been working on the data for this question, I would be interested to find out if you found anything. Without looking into it, my guess would be that there should not be much of a shift. I would expect the energies to be within a certain range of values somewhat close to each other due to the energetics of beta decay.
You need a minimum amount of energy for beta decay, and I would assume the transitions to have a maximum.
If you were thinking of spectroscopic analysis of isotopes, that would be very interesting. I was thinking also that there may be a secondary mecanism that could help identify such signatures. Things like secondary electrons or auger electrons.
Valdo
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I got the feeling you have been working on the data for this question
Hi Valdo, Yep!
As you know, a transition also alters the nuclear spin between parent and daughter. The question is whether this happens progressively or as “an event”.
Actually I’m expecting two answers. Some transitions put the daughter in a higher energy state, which then results in a gamma (or series of gammas) to the ground state for that isotope. In this case I would expect a spectral change to accompany the gamma emissions.
However I’m hoping the answer is either no, or no evidence.
My model for a transition without a gamma component comes up with a parameter indicating that the spin remains constant as the decay energy is lost. (= no spectral change) Also although the decay energy manifests as heat, my model also shows a constant nuclear temperature during the process. In other words the decay process is analagous to the latent energy of a change of state (liquid to solid). In my model the change of spin arises from an exchange of momentum between the lepton and its parent nucleon as a cusp event.
There's a limit on attachment size in this forum, and no facility to send attachments in the message system, so if you (or anyone else) want to see or discuss the supporting data you will need to contact me direct.
Graham
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Can you explain this term "spectral signature of the isotopes", I don't understand.
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Hi Mitch.
As I understand it, each element and Isotope has a distict pattern of absorption lines. The question is whether this is absolute, i.e the "signature" of an isotope remains constant up to the point when emission occurs, and the signature changes to that of the daughter.
The numerical model I've developed confirms this, in that the decay energy is a conversion of mass to heat at the rate determined by the half-life, whilst the nuclear spin and temperature remain constant. If there were anomalies in the spectrum during the decay, my model would be suspect.
Graham
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I think you're merging more concepts together than I'm accustomed to. I've never heard absorption lines described for isotopes, it is usually customary to talk about their emissions. So, what absorption lines are you talking about?
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Hi Mitch.
Yes I have been mixing concepts. I was trying to find if there were aspects of the behaviour of atoms which were reflected in the structure of the nucleus.
Maybe I have to rephrase my questions. I will think some more.
No one ever came back about the "three curves of stability" which i described in the attachment to my post on "geometry of isotopes".
Graham
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I understand the first 19 elements when ionised fluoresce mainly in Blue-Violet ranges. Is this the phenomenon referred to here?
Please can anybody tell me the colour wavelengths (roughly) which Mercury would emit when ionised?