1480 
complex Fourier integral in which integration over the parameter 
@ is carried from minus to plus infinity. For this treat- 
ment we may no longer regard « as a simple positive quantity 
and must take account of the change in sign of the phase shift 
indicated by equation (6) for negative values of i. 
2.3 Suppose the incident wave is now given by the general 
form? 
-Y2 
fri (t) = (a7) “| pee exp(cut) Aw (8) 
where 
Pow) = er)"| Re) exp (wt) ae (3) 
Applying the phase shift indicated by equation (6), 
[- 2) 
pt) : Cen) | glu) exp (Cut r Cable fu) des (0) 
From which it follows, upon substitution of the trigonometric 
form of exp (21 € / wv) » that: 
ple) iS ples Cos KE + F(t) Sye Ae (11) 
where a) 
Fle) = (eT) "| £tel pies) exp(iwt) de 
= era je (12) 
— od 
