# Inelastic Tunneling Current Equation help

1. May 28, 2012

### Huor Earfalas

In this paper ("Molecular Vibration Spectra by Inelastic Electron Tunneling" by J. Lambe & R.C. Jaklevic Phy.Rev. Vol 165, Article 3), the author showed that when external voltage is applied across a metal-insulator-metal, the current passing through the insulator is shown to be:

I(V) = N($\frac{dj}{dV}$)[$\frac{4\pi me}{\bar{h}^2\phi}$]ln($\frac{l}{r0}$)....... (formulae continues)

I am unfamiliar with the parameter r0, which is called, in the paper, the cut-off distance in the vicinity of the molecule. I believe this is a constant and unique to different molecules, if so, where can I find data regarding this? I greatly appreciate your time and effort for explaining this term to me :)

EDIT: Unfortunately I was not able to post link since I am new.