Rectangular Potential Barrier Boundary Conditions with E=V

[GoliathPSU]

Homework Statement

I am trying to calculate the transmission and reflection coefficients for rectangular finite potential barrier between (-a, a) for a particle of mass m with energy equal to the height of the barrier (E = V₀ > 0).

Homework Equations

http://en.wikipedia.org/wiki/Rectangular_potential_barrier#E_.3D_V0

The Attempt at a Solution

I understand the general solutions for the potential region are linear, and am trying to match the boundary conditions to evaluate the coefficients, but I am having trouble understanding why the Wikipedia page linked above has the imaginary number disappear from the exponentials attached to the C_l term. Instead there is just a + sign there. Is this just a mistake on the page? As far as I can tell, there is no reason the term should suddenly become real.

 

[BvU]

I agree with you. No one notices, because they let C_l=0 for T and R .

By the way, usually the barrier is from x=0 to x=a to make applying the boundary conditions a little easier.