Stripping It Bare
Essentially, a black hole is an object whose gravity is so strong that it sucks in surrounding objects. That’s what became of a small molecule that researchers from the Stanford operated SLAC National Accelerator Laboratory blasted with the world’s most powerful X-ray laser. The molecule turned into an atom-sucking “molecular black hole.”
Worry not, however, as such an effect requires an X-ray laser that’s “a hundred times more intense than what you would get if you focused all the sunlight that hits the Earth’s surface onto a thumbnail,” Sebastien Boutet said in a press release. That’s how strong the Coherent X-ray Imaging instrument used for this experiment is, said Boutet, who is a co-author of the study the team published in the journal Nature. It’s capable of releasing hard X-rays by using the highest possible energies available from the equipment.
The researchers used special mirrors to focus the X-ray beam into a very small spot, which was a little bit over 100 nanometers in diameter, to check three types of samples with heavy atoms: individual xenon atoms (with 54 electrons each) and two types of molecules with single iodine atoms (containing 53 electrons each). They didn’t expect the extreme effect the X-ray laser would actually have on these samples, which surpassed their calculations based on previous studies.
When blasted with the X-ray laser beam from the Coherent X-ray Imaging instrument, the molecule’s iodine atom lost more than 50 electrons with just 30 femtoseconds — or millionths of a billionth of a second. The void that was left then pulled in electrons from the rest of the molecule, which it also blasted out before finally blowing up.
“We think the effect was even more important in the larger molecule than in the smaller one, but we don’t know how to quantify it yet,” lead researcher Artem Rudenko explained in the press release. “We estimate that more than 60 electrons were kicked out, but we don’t actually know where it stopped because we could not detect all the fragments that flew off as the molecule fell apart to see how many electrons were missing. This is one of the open questions we need to study.”
That effect, of course, wasn’t something the researchers intended. However, they did learn a very important lesson from it. Using X-rays with ultrahigh intensities is necessary for experiments that try to image individual biological objects — such as bacteria and viruses — at a high resolution. At the same time, it’s also useful in studying the charge dynamics of complex molecules and to understand how matter behaves in extreme conditions.
“For any type of experiment you do that focuses intense X-rays on a sample, you want to understand how it reacts to the X-rays,” Daniel Rolles, who also headed the study, said in the press release. “This paper shows that we can understand and model the radiation damage in small molecules, so now we can predict what damage we will get in other systems.”