so the inverse exponential fit looks very promising, when it's allowed to zero the force at an arbitrary location. The problem is that the constants seem absurd. I'm going to try a DLVO fit, maybe including the region after it "jumps" and see if that works.
implemented a basic DLVO force regression. This allows much greater range of variable selection and generally better agreement. The constants need to be looked at in much greater detail though. Also, i will look at extending the window size to the "down" portion of the curve. will update to version 8 for this purpose.