Many of the posts on Big Ten Science do not deal with discoveries about the natural world per se, but instead deal with advances in technology that will in turn lead to a greater understanding of the world around us. For example, yesterday’s post on a new technique to study 3D cultures of breast tissue will allow scientists to study the effects that thousands of compounds have on it as related to breast cancer.
Today’s post is no different in that regard. It deals with a technological advance that – together with a multitude of other techniques – should garner greater insight into the workings of the world. But today, instead of looking at tissue reactions, we’re going much, much smaller. Today’s post is about an advancement in the imaging of atomic bonds.
The atom is much, much too small to take a picture of. At best, we can shoot forms of energy with minute wavelengths – electrons and x-rays, for the majority – and detect how their motions are affected by the atom in question. By doing this countless numbers of time, the data piles up until we get a good idea of what the atom “looks” like.
These techniques are tried and true, but the issue comes on a matter of scale. In order to “see” atoms, you have to have energy waves with wavelengths on the same scale as what it is you’re trying to see. It’s kind of like those toys at science museums that have thousands of tiny metal pegs. When you push up on them with your hand – or anything else for that matter – the pegs form that shape by being displaced. But if the individual pegs were bigger than your hand – or if you were trying to form the shape of a mosquito – they wouldn’t do much good.
Slowly but surely, science is getting to the point of creating such wavelengths. Another hurdle is that of time. One of the most anticipated advancements in chemistry is the ability to witness molecular bonds and chemical reactions as they are happening. But in order to do so, the pulses of electrons or x-rays have to be mere femtoseconds – or quadrillionths of a second – long. Otherwise, they’re not fast enough to catch the action.
Scientists at Ohio State, however, recently developed a technique that shows promise for being able to hurdle both of these obstacles. But instead of using external forms of “light,” they are instead illuminating the molecular bonds from within the molecule itself.
Perhaps you can remember back to your high school chemistry days and remember the fact that electrons orbit the nucleus in different, set orbitals. What’s more, each orbital has a different energy level, and electrons like to fill the lowest energy ones first.
However, when an atom is struck by some form of energy, an electron (or multiple electrons) becomes excited and jumps up to a higher orbit. But what goes up must come down, and when it does it releases a small packet of energy called a photon. You know it better as light.
In the technique recently described in Nature, Louis DiMauro and his team take advantage of this. The technique uses a specialized laser to excite the electrons orbiting atoms in a molecule as they are forming their bonds. By doing so in a very specific way in a very specific ionization field, photons of light are emitted in a predictable way. The researchers can look to see how the atoms in the molecule and their molecular bonds affect the photos of light. After doing this many times over, a picture begins to emerge of exactly where everything is and what it is doing.
In this recent experiment, DiMauro and company managed to successfully image two already well-known molecules, simple nitrogen (N2) and simple oxygen (O2). The challenge now becomes to ramp the technique up in order to study large, complex molecules. And that is a very large challenge indeed.
In reality, the technique will take years, if not decades, to achieve the ability to actually study anything of worth. Even when it does come to fruition, other technologies also will have made large strides towards imaging chemistry in action. But that’s the way science works. Incremental steps from many different lines of research eventually yield results.
In the end, it will be the combination of hundreds of scientists working on several different techniques over long periods of time that will unlock the mysteries of the atomic world.