Liquid Water Vibrates Slower When Confined at the Nanoscale

Liquid Water Vibrates Slower When Confined at the Nanoscale

Scientific Achievement
(A) Illustration of “aloof” EELS (beam positioned ~10nm from sample to prevent radiation damage) of BN-encapsulated liquid cell; (B) EEL spectra showing the difference between O-H and O-D modes as well as lowering of the O-H mode from its bulk value of 420 meV.  (hi-res image)

Monochromated electron energy loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM) can distinguish between hydrogen and deuterium vibrational modes and shows that encapsulating a small volume of water between boron nitride (BN) monolayers slows down these hydrogen modes.

Significance and Impact

Results represent a milestone for liquids, fluid interfaces, and isotope-labeled materials characterization with nm-level spatial resolution that combines nanoscale imaging and vibrational spectroscopy with isotopic sensitivity.

Research Details

– Vibrational EEL spectra were acquired using a Nion Hermes monochromated and aberration-corrected (MAC)-STEM operated at 60kV in an “aloof” geometry.

 

J. R. Jokisaari, J. A. Hachtel, X. Hu, A. Mukherjee, C. Wang, A. Konecna, T. C. Lovejoy, N. Dellby, J. Aizpurua, O. L. Krivanek, J. C. Idrobo, and R. F. Klie, "Vibrational spectroscopy of water with high spatial resolution," Advanced Materials (2018).  DOI: 10.1002/adma.201802702

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