WASHINGTON, May 14 (Xinhua) -- Swedish scientists used a powerful X-ray laser to heat water from room temperature to 100,000 degrees Celsius in less than one tenth of a picosecond (one trillionth of a second), creating the fastest water heater in the world.
The study published on Monday in the journal Proceedings of the National Academy of Sciences revealed that the experiment produced an exotic state of water that the researchers can learn more about the peculiar characteristics of Earth's most important liquid.
The team led by Carl Caleman at Sweden's Uppsala University used the X-ray free-electron laser source at the SLAC National Accelerator Laboratory in the United States to shoot extremely intense and ultra-short flashes of X-rays at a jet of water.
"It is not the usual way to boil your water," said Caleman. "Normally, when you heat water, the molecules will just be shaken stronger and stronger."
According to Caleman, on the molecular level, heat is motion, meaning the hotter, the faster the motion of the molecules, and this can be achieved via heat transfer from a stove, or more directly with microwaves that make the water molecules swing back and forth ever faster in step with the electromagnetic field.
"Our heating is fundamentally different", said Caleman. "The energetic X-rays punch electrons out of the water molecules, thereby destroying the balance of electric charges. So, suddenly the atoms feel a strong repulsive force and start to move violently."
In less than 75 femtoseconds, or 75 millionths of a billionth of a second, the water goes through a phase transition from liquid to plasma. A plasma is a state of matter where the electrons have been removed from the atoms, leading to a sort of electrically charged gas.
"While the water transforms from liquid to plasma, it still remains at the density of liquid water, as the atoms didn't have time to move significantly yet," said the paper's co-author Olof Jonsson from Uppsala University.
This exotic state of matter is nothing that can be found naturally on Earth. "It has similar characteristics as some plasmas in the sun and the gas giant Jupiter, but has a lower density. Meanwhile, it is hotter than Earth's core," said Jonsson.
