Hello.

 

I was wondering, why is relaxation time used as the time-scale for radioisotopes tracers and not half-life instead?

On 5/4/2018 at 6:02 PM, davichi said:

Hello.

I was wondering, why is relaxation time used as the time-scale for radioisotopes tracers and not half-life instead?

 

 

 

 

Edited April 8, 20187 yr by davichi

I suppose it depends what you are measuring, can you provide more detail, rather than just repeating the question?

Half lives are really only strictly applicable to first order reactions, such as simple radiactive decay.
But say you did a radio-isotope dilution analysis with an isotope of half life 10,000 years.
What use would knowing that number be during your afternoon visit to the Chemistry lab?
The actual activity would be essentially constant for the duration of the experiment.

Relaxation methods are often used in Chemistry to investigate fast chemical reactions, when the relaxation to equilibrium is suddenly disturbed the return to equilibrium is mostly first order.

 

Edited April 8, 20187 yr by studiot

On 4/5/2018 at 12:02 PM, davichi said:

Hello.

 

I was wondering, why is relaxation time used as the time-scale for radioisotopes tracers and not half-life instead?

I'm wondering why you think that relaxation time  is used.

Google gives just 127 hits for "relaxation time" "radioisotope tracers".

 

For NMR?

https://en.m.wikipedia.org/wiki/Relaxation_(NMR)

Edited April 8, 20187 yr by Endy0816
linkin

1 hour ago, Endy0816 said:

For NMR?

https://en.m.wikipedia.org/wiki/Relaxation_(NMR)

 

Yeah, but as John says, what does that have to do with general use in connection with radiosotope tracers?

Edited April 8, 20187 yr by studiot

7 hours ago, studiot said:

Yeah, but as John says, what does that have to do with general use in connection with radiosotope tracers?

May be on the wrong track, thought I saw a table or something though... Am hoping OP can clarify.

As far as I am aware, different fields have different conventions in expressing first-order processes.  I don't know of any reason why one convention or another is used.