By observing the spectroscopic behavior of single water molecules embedded in a super-cold, cage-like molecular structure, researchers have revealed key features that underlie the diffuse vibrational spectra of hydrogen-oxygen bonds that make studying the two-dimensional surface structure of water a challenge. The results reveal new insights into fundamental molecular mechanics and properties of water. The molecular structure and properties of the surface of water have been difficult to study as the surface is obscured by the vibrations of "blurry" oxygen-hydrogen bonds that muddy the surface spectrum of bulk water signature. However, using cold clusters of 20 water molecules surrounding a cesium ion, Nan Yang and colleagues were able to isolate single H2O molecules and observe individual frequencies of related OH groups using cryogenic ion spectroscopy. Furthermore, Yang et al. were able to manipulate the position of a single H2O molecule within the network of 19 other deuterated water molecules (D20). According to the results, the vibrational frequencies of the two OH groups on the same water molecule were site-dependent and demonstrate that bound OH companions account exclusively for lower energy bands in the spectrum.
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Journal
Science