Homework Help: Mossbauer Effect in Iron-57

1. Mar 6, 2012

Mr LoganC

1. The problem statement, all variables and given/known data
Calculate the Doppler velocity needed to compensate for the recoil energy.

2. Relevant equations
$V=\frac{E_{0}}{m c}$

3. The attempt at a solution
I found the recoil energy to be $1.95\times10^{-3}$ eV.
And for Iron-57, $E_{\gamma}$ is 14.4KeV. Which is approximatly equal to $E_{0}$.
So just plugging these values into the above equation, I get 81.27m/s which seems a bit high, as many articles site around 10mm/s!

Perhaps units I am using should be in something else? Or maybe I am using the completely wrong equation?

2. Mar 7, 2012

M Quack

From the wiki: http://en.wikipedia.org/wiki/Mössbauer_effect

3. Mar 7, 2012

Mr LoganC

Ohhh..... and of course I'm calculating it for a "Free" atom, not one bound in a solid! So the higher velocity makes sense!

Thank you so much for the help!

4. May 10, 2012

Rajini

Hi,
You answer for recoil velocity seems to be correct (i get 81.47 m/s). The 10 mm/s velocity is not the recoil velocity. It is the speed of transducer, i.e. the vibrating velocity of the Mössbauer source to acquire a complete Mössbauer spectrum..1 mm/s is equal to 48.075 neV ([itex]E_{D}=\frac{E_{\gamma} v}{c}[\itex], take v=1 mm/s and you will get 48.075 neV).
Cheers, Rajini