Nav: Home

Ultrafast hydrogen bond dynamics of liquid water revealed by THz-induced Kerr effect

August 18, 2020

Liquid water is considered the cornerstone of life and has many extraordinary physical and biochemical properties. The hydrogen bond network of liquid water is widely recognized to play a crucial role in these properties. Due to the complexity of intermolecular interactions and the large spectral overlap of relevant modes, the study of hydrogen bond dynamics is challenging. In recent years, exciting the liquids resonantly with terahertz (THz) waves provides a new perspective for exploring the transient evolution of low-frequency molecular motion. However, water has a large absorption coefficient in THz band, the application of the THz-induced Kerr effect technique in hydrogen bond dynamic research has remained challenging.

In a new paper published in Light Science & Application, a team of scientists, led by Professor Yuejin Zhao from Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology, School of Optics and Photonics, Beijing Institute of Technology, China; Professor Liangliang Zhang from Beijing Advanced Innovation Center for Imaging Technology and Key Laboratory of Terahertz Optoelectronics (MoE), Department of Physics, Capital Normal University, China; and co-workers used an intense and broadband THz pulse to resonantly excite intermolecular modes of liquid water and obtained bipolar THz field-induced transient birefringence signals by adopting a free-flowing water film. They proposed a hydrogen bond harmonic oscillator model associated with the dielectric susceptibility and combined it with the Lorentz dynamic equation to investigate the intermolecular structure and dynamics of liquid water. They mainly decompose the bipolar signals into a positive signal caused by hydrogen bond stretching vibration and a negative signal caused by hydrogen bond bending vibration, indicating that the polarizability perturbation of water presents competing contributions under bending and stretching conditions. The results provide an intuitive time-resolved evolution of polarizability anisotropy, which can reflect the intermolecular modes of liquid water on the sub-picosecond scale.

The THz waves can resonantly excite one or several molecular motion modes in liquids, which is a powerful tool for exploring low-frequency molecular dynamics. These scientists summarize the principle of their work:

"We used a THz electric field to resonantly excite the intermolecular modes of liquid water. The transient rotation of a molecule produces an induced dipole moment, which immediately transfers the momentum driven by the THz field to the restricted translational motion of adjacent water molecules. This translational motion can be assigned to a bending mode and a stretching mode, which can lead to the components of polarizability anisotropy perpendicular and parallel to the hydrogen bonds, respectively, thus resulting in bidirectional performance."

"In the experiment, an intense THz excitation source and an ultrathin flowing water film that replaces traditional cuvettes are the basis for achieving high-quality signals." they added.

"The ultrafast intermolecular hydrogen bond dynamics of water revealed by a broadband THz pump pulse can provide further insights into the transient structure of liquid water corresponding to the pertinent modes. This breakthrough could open a new venue for detecting the physical mechanisms of the gas phase of water and crystalline and amorphous ices, as well as the complex interaction of reagents with solvent water molecules." the scientists forecast.

Light Publishing Center, Changchun Institute of Optics, Fine Mechanics And Physics, Chinese Academy

Related Terahertz Articles:

Terahertz receiver for 6G wireless communications
Future wireless networks of the 6th generation (6G) will consist of a multitude of small radio cells that need to be connected by broadband communication links.
A breakthrough in developing multi-watt terahertz lasers
Researchers from Lehigh University are reporting another terahertz technology breakthrough: they have developed a new phase-locking technique for plasmonic lasers and, through its use, achieved a record-high power output for terahertz lasers.
Doing more with terahertz: Simplifying near-infrared spectroscopy systems
Researchers from Beihang University, China, and Tokushima University, Japan, have developed a terahertz spectroscopy scheme that offers outstanding resolution using a single laser.
Terahertz radiation can disrupt proteins in living cells
Researchers from the RIKEN Center for Advanced Photonics and collaborators have discovered that terahertz radiation, contradicting conventional belief, can disrupt proteins in living cells without killing the cells.
A nanoscale device to generate high-power Terahertz waves
Researchers at EPFL have developed a nanodevice, described today in Nature, that operates more than 10 times faster than today's fastest transistors.
Record-breaking terahertz laser beam
Terahertz radiation is used for security checks at airports, for medical examinations and also for quality checks in industry.
A trick for taming terahertz transmissions
Osaka University researchers have invented a wireless communication receiver that can operate in the terahertz frequency band.
Researchers substantially boost sensitivity of terahertz gas analysis
A new advance promises to increase the sensitivity of high-resolution spectrometers that perform chemical analysis using terahertz wavelengths.
Researchers generate terahertz laser with laughing gas
Researchers from MIT, Harvard University, and the U.S. Army have built a compact device, the size of a shoebox, that produces a terahertz laser whose frequency they can tune over a wide range.
Terahertz technology escapes the cold
The group of Jérôme Faist in the Department of Physics at ETH Zurich achieved the first realization of a terahertz quantum cascade laser operating without cryogenic cooling.
More Terahertz News and Terahertz Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at     You can read The Transition Integrity Project's report here.