<html><body><div style="font-family: arial, helvetica, sans-serif; font-size: 12pt; color: #000000"><div></div><div><br></div><div data-marker="__QUOTED_TEXT__"><div style="font-family: arial, helvetica, sans-serif; font-size: 12pt; color: #000000"><div><div style="font-family: arial, helvetica, sans-serif; font-size: 12pt; color: #000000"><div><div style="font-family: arial, helvetica, sans-serif; font-size: 12pt; color: #000000;"><div style="font-family: arial, helvetica, sans-serif; font-size: 12pt; color: #000000;"><div><div style="color: #000000; font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none; text-align: center;"><strong><b><span lang="HR" style="font-size: 16pt; color: black;"><img><img src="cid:fb559ca8379da07816ebeb024a88bd13dae62179@zimbra" data-mce-src="http://mail.ifs.hr/service/home/~/?auth=co&id=75467&part=2.2&t=1481207646976"></span></b></strong></div><div style="color: #000000; font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none; text-align: center;"><p style="text-align: center; margin: 0px;" align="center"><b><span lang="EN-GB" style="font-family: 'Century Gothic',sans-serif; color: #5f5f5f;">Institut za fiziku, Bijenička cesta 46,</span></b></p><p style="text-align: center; margin: 0px;" align="center"><b><span lang="EN-GB" style="font-family: 'Century Gothic',sans-serif; color: #5f5f5f;">predavaonica u zgradi Mladen Paić</span></b></p><strong><b><span lang="EN-GB" style="font-size: 14pt; font-family: 'Century Gothic',sans-serif; color: #993300;">četvrtak, 11. svibnja 2017., u 15:00 sati</span></b><br></strong></div><div style="color: #000000; font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none; text-align: center;"><strong></strong> </div><div style="text-align: center;"><span style="color: #55913c; font-family: 'Times New Roman', serif;"><span style="font-size: 21.3333px;"><b>Single-particle excitations and incipient ferroelectricity of nanoconfined water molecules</b></span></span></div><div style="text-align: center;"><span style="font-family: 'Century Gothic', sans-serif;"><span style="font-size: 18.6667px;"><b>dr. Boris P. Gorshunov</b></span></span></div><div style="color: #000000; font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none; text-align: center;"><b></b> </div><div style="text-align: center;"><span style="font-family: 'Century Gothic', sans-serif;"><span style="font-size: 14.6667px;"><b>Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141700 Russia</b></span></span></div><div style="text-align: center;"><span style="font-family: 'Century Gothic', sans-serif;"><span style="font-size: 14.6667px;"><b>A. M. Prokhorov General Physics Institute, RAS, Moscow, 119991 Russia</b></span></span></div><div style="text-align: center;"><span style="font-family: 'Century Gothic', sans-serif;"><span style="font-size: 14.6667px;"><b>1. Physikalisches Institut, Universität Stuttgart, 70569 Stuttgart, Germany</b></span></span></div><div style="color: #000000; font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none; text-align: center;"><b><b><span lang="EN-GB" style="font-size: 11pt; font-family: 'Century Gothic',sans-serif;"></span></b></b><br></div><div style="color: #000000; font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none; text-align: center;"><br></div><div style="text-align: left;"><p style="text-align: left; margin: 0px; line-height: 115%;"><br></p><p style="text-align: left; margin: 0px; line-height: 115%;">By using radiofrequency and terahertz spectroscopy (frequencies 1 Hz to 10<sup>14</sup> Hz), at temperatures 0.3 K to 300 K, we have studied excitations of an ensemble of single water molecules that are caged within subnano-sized (0.5 nm) voids formed by ions of the beryl (Be<sub>3</sub>Al<sub>2</sub>Si<sub>6</sub>O<sub>18</sub>) crystal lattice. Measurements on dehydrated samples allow to extract absorption lines caused exclusively by water molecules, on the background of phonons resonances. In the infrared range, well-known H<sub>2</sub>O intramolelular modes <i>ν</i>1 (symmetric elongation), <i>ν</i>2 (bending), and <i>ν</i>3 (asymmetric elongation) of the H<sub>2</sub>O are observed. Spectra recorded below 1000 cm<sup>−1</sup> reveal rich set of highly anisotropic absorption bands of the low-energy response of caged H<sub>2</sub>O molecules. Performing the DFT analysis we can assign the bands to librational and translational vibrations of separate water molecules that are weakly (van der Waals) coupled to the cages’ ldquo;walls”. At terahertz frequencies, we detect clear signs of emerging incipient ferroelectric phase within water molecules that are coupled via long-range dipole-dipole forces, with the shorter-range hydrogen bonds "switched off" due to large (4 to 9 Angstroms) intermolecular spacing. On cooling from room temperature, the static permittivity increases according to the Curie-Weiss law as a collective ferroelectric soft mode develops in the terahertz frequency range. At temperatures below 10 K, quantum fluctuations eventually suppress the ferroelectric phase transition and lead to a saturation of the soft mode parameters and of the static permittivity. We describe our results within the framework of a mean-field microscopic model that considers rotational and librational motions of interacting water molecular dipoles in a six-well potential.</p><p style="color: #000000; font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none; text-align: left; margin: 0px; line-height: 115%;"><span style="font-family: arial,helvetica,sans-serif;"> </span></p><p style="color: #000000; font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none; text-align: left; margin: 0px; line-height: 115%;"><b style="font-size: 12pt;"><span lang="EN-GB" style="font-size: 12pt; font-family: 'Century Gothic',sans-serif;"><b><span lang="EN-GB" style="font-size: 11pt;"> </span></b></span></b><span style="font-family: arial,helvetica,sans-serif;"></span></p></div><div style="color: #000000; font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none; text-align: left;"><b><span lang="EN-GB" style="font-size: 12pt; font-family: 'Century Gothic',sans-serif;"><b><span lang="EN-GB" style="font-size: 11pt; font-family: 'Century Gothic',sans-serif;"> </span></b></span></b></div><div style="color: #000000; font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none; text-align: right;"><b><span lang="EN-GB" style="font-size: 12pt; font-family: 'Century Gothic',sans-serif;"><b><span lang="EN-GB" style="font-size: 11pt; font-family: 'Century Gothic',sans-serif;">Voditelji seminara IF-a: <a href="mailto:natasav@ifs.hr" target="_blank">Nataša Vujičić</a> i <a href="mailto:damirs@ifs.hr" target="_blank">Damir Starešinić</a></span></b></span></b></div></div><div style="color: #000000; font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none;"> </div></div></div></div></div></div></div><br></div></div></body></html>