Ultrafast heating of water: This pot boils faster than you can watch it "Scientists from the Hamburg Center for Free-Electron Laser Science have devised a novel way to boil water in less than a trillionth of a second. The theoretical concept, which has not yet been demonstrated in practice, could heat a small amount of water by as much as 600 degrees Celsius in just half a picosecond (a trillionth of a second). That is much less than the proverbial blink of an eye: one picosecond is to a second what one second is to almost 32 millennia. This would make the technique the fastest water-heating method on Earth..."
http://phys.org/news/2013-12-ultrafast-pot-faster.html ---------------------------------------------------------------- Ultrafast energy transfer to liquid water by sub-picosecond high-intensity terahertz pulses: An ab initio molecular dynamics study Liquid water is the most common environment for chemical and biological processes. Most of them occur as a consequence of thermal random fluctuations of the environment, which every once in a while create the conditions for a chemical reaction to occur. Therefore, bringing a large amount of energy to liquid water in a as short as possible time can open new avenues for the controlled exploration of thermally activated chemical reactions in liquids. In this work we address the sub-picosecond response of liquid water to an intense and ultrashort THz pulse as those that can be generated at X-FELs and on state-of-the-art table top setups. The main questions that we try to answer are: how does energy get transferred from the THz pulse to different vibrational modes of liquid water? How does the structure of water evolve as a function of time under the effect of the pulse? We address these questions through ab-initio molecular dynamics simulations of liquid water interacting with a one-cycle THz pulse of intensity 10^10 W/cm2, 100 cm-1 (~3 THz) photon energy and a pulse duration of about 250 fs. We find that after a very rapid disruption of the hydrogen bonding structure of the liquid, the water molecules start to violently move against each other. In a time-scale of about 500 fs, the temperature jump from 300 to about 900 K is completed and about 25 THz photons per water molecule have been absorbed. The energy flows from inter- to intra-molecular modes and a quasi-equilibrium state is reached within 1 ps. Dramatic structural changes can be seen in the modification of the O-O and O-H radial distribution functions. A substantial modification of the time resolved X-ray diffraction (TR-XRD) pattern from double to single peaked during the THz pulse is a consequence of such ultrafast rearrangements (See Figure). The properties as a matrix for chemical processes of the transiently hot and structureless phase of water at the density of the liquid will be the subject of future explorations. https://desy.cfel.de/cfel_theory_division/highlights/ultrafast_energy_transfer_to_liquid_water_by_sub_picosecond_high_intensity_terahertz_pulses_an_ab_initio_molecular_dynamics_study/
