title: Probing hydrophilic interface of solid/liquid-water by nanoultrasonics.
abstract: Despite the numerous devoted studies, water at solid interfaces remains puzzling. An ongoing debate concerns the nature of interfacial water at a hydrophilic surface, whether it is more solid-like, ice-like, or liquid-like. To answer this question, a complete picture of the distribution of the water molecule structure and molecular interactions has to be obtained in a non-invasive way and on an ultrafast time scale. We developed a new experimental technique that extends the classical acoustic technique to the molecular level. Using nanoacoustic waves with a femtosecond pulsewidth and an ångström resolution to noninvasively diagnose the hydration structure distribution at ambient solid/water interface, we performed a complete mapping of the viscoelastic properties and of the density in the whole interfacial water region at hydrophilic surfaces. Our results suggest that water in the interfacial region possesses mixed properties and that the different pictures obtained up to now can be unified. Moreover, we discuss the effect of the interfacial water structure on the abnormal thermal transport properties of solid/liquid interfaces.
authors.affiliation: Department of Electrical Engineering and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Pierre-Adrien
authors.initials: PA
authors.lastname: Mante
authors.affiliation: Department of Electrical Engineering and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Chien-Cheng
authors.initials: CC
authors.lastname: Chen
authors.affiliation: 1] Department of Electrical Engineering and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan [2] Institute of Physics and Research Center for Applied Science, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Yu-Chieh
authors.initials: YC
authors.lastname: Wen
authors.affiliation: Department of Electrical Engineering and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Hui-Yuan
authors.initials: HY
authors.lastname: Chen
authors.affiliation: Department of Electrical Engineering and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Szu-Chi
authors.initials: SC
authors.lastname: Yang
authors.affiliation: Molecular Imaging Center, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Yu-Ru
authors.initials: YR
authors.lastname: Huang
authors.affiliation: Molecular Imaging Center, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: I-Ju
authors.initials: IJ
authors.lastname: Chen
authors.affiliation: Institute of Atomic and Molecular Science, Academia Sinica, Taipei 10617, Taiwan.
authors.forename: Yun-Wen
authors.initials: YW
authors.lastname: Chen
authors.affiliation: Laboratoire d'Acoustique, LAUM, UMR No. 6613 associée au CNRS, LUNAM Université, Université du Maine, Avenue Olivier Messiaen, 72085 Le Mans, France.
authors.forename: Vitalyi
authors.initials: V
authors.lastname: Gusev
authors.affiliation: Department of Material Science and Engineering, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Miin-Jang
authors.initials: MJ
authors.lastname: Chen
authors.affiliation: Institute of Atomic and Molecular Science, Academia Sinica, Taipei 10617, Taiwan.
authors.forename: Jer-Lai
authors.initials: JL
authors.lastname: Kuo
authors.affiliation: Institute of Electro-Optical Science and Engineering and Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan.
authors.forename: Jinn-Kong
authors.initials: JK
authors.lastname: Sheu
authors.affiliation: 1] Department of Electrical Engineering and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan [2] Institute of Physics and Research Center for Applied Science, Academia Sinica, Taipei 115, Taiwan [3] Molecular Imaging Center, National Taiwan University, Taipei 10617, Taiwan [4] Graduate Institute of Biomedical Electronics and Bioinformatics and Center for Optoelectronics Medicine, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Chi-Kuang
authors.initials: CK
authors.lastname: Sun