Quantum Mechanics Can Be Useful Too!
Nowadays, it seems that quantum mechanics is seen more as “spooky” than practical. Thus, I am here to “de-mystify” some of the science behind a fascinating process that’s yet to be simulated properly. My research group investigates the theory behind what is called Interatomic Coulomb Electron Capture (ICEC). This fascinating universal quantum process is yet to be fully understood, and we are here to change that. Someday, this could be an incredibly useful tool to revolutionize atomic and quantum chemical energy transfers.
ICEC In A Nutshell
The general process includes 3 main steps that occur simultaneously. We’ve got two atoms, atom A and atom B (like in the diagram below), and we have a free electron. First, this free electron (with some energy ε) is shot in and is then captured into atom A’s orbit, which results in an emission of energy in the form of a photon. This energy is then absorbed by its neighboring atom B. This results in atom B ejecting an electron out of its orbit , with some energy ε’. This is what is called photo-ionization.
Why This Is Can Be Useful
This process can potentially change the way we see energy transfer. This is because the energy of the outgoing electron (with energy ε’ in Figure 1.) can be greater than the energy of the incoming free electron. This means that if we were to consider this process as an isolated system, it’s actually a very efficient way of “getting more than you put in”.
A Deeper Look Into The Interatomic Process
Let’s now think of this system, but a little more in depth about how each event transpires.
First, we throw in an electron in the direction of atom A. For our purposes, let’s ignore how exactly its being thrown in, just know that it is physically possible. From here, we have 2 main possible outcomes: either it can be scattered, which means that it bounces off the atom at some trajectory — or, it can be captured. Electron capture means that the electron is now in this atom’s orbit and it’s now part of the atom. Then comes the ionization/excitation!
So the reason atom A releases energy in form of a photon is because entrapping the electron frees up some energy, which has to be given away as shown in the second step of Figure 1. This energy then is then passed on to atom B in the form of heat wave or flashes of light. Now that atom B has this extra energy, an electron is kicked out by the energy impact from atom A’s cool down (as shown in the last step of ICEC in Figure 1).
If you want to think of this thermally, the free electron shot in is like a hot bullet — in order to hold it, it has to be cooled down. That is why A passes of the energy. It literally heats up an electron on atom B in order to have it’s own electron cooler and bearably bound.
The Simulation Process
Our main task as scientists is to investigate the propability of this process occurring, given different sets of parameters. The probability of ICEC occurring depends on several different factors. It depends on the atomic species chosen, the distance between the two atoms, the energy at which the electron is thrown in at, and most importantly — the probability cross sections, which is where my focus lies.
A cross section is like the size of a target in archery or darts. How much “wiggle-room” do I have? I.e. How big is the target? Of course, the bigger the target, the better chances you have of hitting the target. And that’s kind of what a probability cross section does.
On a more technical side, in order to simulate such a process we use what is called Hartree-Fock method of computation. This is a developed way of approximating our system so that we can determine the wave function and energy of a many-body quantum system in a stationary state. This allows physicists like us to take this complicated family of probability distributions, and make it into something more tangible.
My goal is to create a framework in which we can predict the outcome of different scenarios and their probability cross sections. From this simulation, we can gather insights that wouldn’t have been possible otherwise. Even though we know it can observed, it doesn’t mean that we have any insight about the process itself. For instance, if you take the temperature of your city for a week and then plot it, does that mean you understand why the weather changed? Of course not. Hence, our drive to simulate ICEC. Our goal is to be able to fully understand the inner working of the process and what makes it so unique and universal. Then hopefully, we find some insight that can further our use of quantum energy transfers, and use it to our advantage.
What Is On The Horizon
As is the case with most theoretical physics, it can be very hard to predict the practical use of your research. Nevertheless, the most fruitful and important discoveries happen without an end goal in mind. Without these pursuits, we wouldn’t have the technology we are able to have today. Who would have known that a simple radio wave detection could leave to such incredible advances in technology. It’s only once we are able to understand how universal processes work that we can begin to postulate it’s role in society, and how it can contribute the advancement of knowledge and scientific discovery.
 Gokhberg, K. & Cederbaum, L. S. (2010). Interatomic Coulombic electron capture. Phys. Rev. A, 82, 052707.