 Okay, in our experiment we want to measure the reorganization energy of a molecule on an insulator. Let's suppose you put a molecule on an insulator. The insulator we are using is sodium chloride which has some charges, positively charged sodium ions and negatively charged chloride ions. So if you put a charge on your molecule, let's say a charge of plus one electron, then the charges within the sodium chloride film will react to that charge and positive ones will be repelled, negative ones will be attracted. And this equals like loading a spring. And what we want to measure is the energy that goes into loading that spring called the reorganization energy. The molecule we are investigating is naphthalosionine. So that's its molecular structure over here. And next to it is an AFM image that we took. So that's naphthalosionine or MPC. There's a method that is commonly used to measure such energy transitions and energies. And that method is scanning tunneling microscopy. So that is STM. And in STM you put a conductive tip, so that's a tip, above your molecule. So in our case MPC, naphthalosionine, sitting on your insulator. In STM you need a conductive substrate. You can do that by having a metal film below and now you can measure a tunneling current, which is what you do in scanning tunneling microscopy. So you add a charge to your molecule and then that charge goes to the conductive substrate. And you can measure currents and you can go down to about maybe a million electrons per second, which is 100 femto ampere, and you can measure energy transitions. The problem is you can measure only one of those energy transitions. You can only measure the transition going from here to here. So for charging. And this you do by measuring the current with your STM, the current I. The problem is you cannot measure the backward transition. The problem is if that molecule is charged it gets neutralized by tunneling to the metal substrate. So the obvious solution which looks simple is you remove your metal substrate. Your molecule cannot be neutralized by tunneling to the metal. However you have a problem now. You cannot measure a tunneling current anymore. So you cannot do STM. However there is another technique also invented by IBM, which can measure single electron charges transferred. And that's AFM, so atomic force microscopy. In this case you don't measure currents but you measure forces and you measure the additional force if one electron charge is added to your molecule. This is a very sensitive and tedious measurement, but you can do that. And then you can count by hand the number of electrons that are transferred and the time it takes until one electron is tunneling from the tip to the substrate. And importantly you can also measure the reverse process. So you can detach that charge and see how long it takes to go to the tip. You have to do that on time scales which are long because the measurement it's a very tiny signal and you need some time to do that. And we measure currents here on the order of one electron per 10 seconds, which equates one zepter ampere. And with this we can now measure both transitions and we can determine the reorganization energy of this process and in general we have a method now to do spectroscopy on such systems where you have molecules or other adsorbates on insulators using the AFM.