The amplitudes and phases of the relevant spectral components of incident E_{ i}(w) and scattered E_{s}(w) radiation are related
E_{s}(w) = E_{i}(w) ·a(w) . 


via the complex scattering amplitude
a_{0}(w) = a_{0}(w) ·e^{if(w)} . 


which can be expressed in terms of
 the modulus a_{0}(w) and
 the phase shift F(w)
of the scattered radiation component
obtained in forward scattering
The kinetics i.e. the time response or response function a_{0}(t) of an individual nucleus to a d
like excitation (the synchrotron radiation pulse) is given by the Fourier transformation:



1
2p


¥
ó
õ
¥

a(w) e^{iwt} dw 



 i 
1
8p


1
t_{0}

s_{0} · f_{LM} · exp 
é
ë 
iw_{0}t  
t
2t_{0}

ù
û 



of the elastic forward scattering amplitude a_{0}(w) [Hyp.Int.97/98(1996)551]


 
k
8p

·s_{0}· 
G_{0}/(^{h}/_{2p})
ww_{0 } iG_{0}/2(^{h}/_{2p})

· f_{LM} 

(8) 
