Journal of Physical Science and Application 1 (2011) 135-147 Inelastic UV Scattering in a Floating Water Bridge Elmar C. Fuchs 1 , Brigitte Bitschnau 2 , Silvia Di Fonzo 3 , Alessandro Gessini 3 , Jakob Woisetschläger 4 and Filippo Bencivenga 3 1. Wetsus, Centre of Excellence for Sustainable Water Technology, Agora 1, 8900 CC Leeuwarden, The Netherlands 2. Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremayrgasse 9/I (A), 8010 Graz, Austria 3. Sincrotrone Trieste S.C.p.A. di interesse nazionale, Strada Statale 14 - km 163,5 in AREA Science Park, 34012 Basovizza, Trieste, Italy 4. Institute for Thermal Turbomachinery and Machine Dynamics, Graz University of Technology, Inffeldgasse 25 A, 8010 Graz, Austria Received: March 25, 2011 / Accepted: Apri l 08, 2011 / Published: August 15, 2011. Abstract: When high voltage is applied to distilled water filled into two beakers close to each other, a watery connection forms spontaneously, giving the impression of a floating water bridge [1-8]. In this work we present the first inelastic ultraviolet scattering data of such an electrohydrodynamic bridge revealing radial gradients of Stokes- and Anti-Stokes shifts and their intensity profiles. Interpretations including density and temperature changes within the bridge are discussed. The obtained data can be satisfactorily explained by the introduction of a second phase consisting of nano bubbles. Results and interpretation are discussed in relation to similar phenomena. Key words: Inelastic UV scattering, floating water bridge, nano bubbles. Nomenclature A B , A C : scaling factors B: flat background c: sound velocity c w : sound velocity of pure water at the corresponding (ρ,T)-value E: energy E a : activation energy I(E): scattering intensity I(ω): scattering intensity k B : Boltzman constant L: vertical detector position M B : bulk modulus of the bridge (bubbles + water) M w : bulk modulus of water Q: wavevector length ΔQ: finite difference between two adjacent wave vectors R: averaged laser penetration depth R(E): instrumental energy resolution function T: temperature (general); temperature of the bridge at the actual R value Corresponding author: Elmar C. Fuchs, Dipl.-Ing. Dr. techn., research field: electrohydrodynamic liquid bridging. E-mail: elmar.fuchs@wetsus.nl. T 0 : 46.1 °C (temperature of the bridge surface) ΔT: T 0 - T (difference between the outside bridge temperature and the temperature at the actual R value) V min : minimum volume allowed for the system X bub : percentage of the bubble phase Greek letters α: scattering angle T : fitting parameter for a constant radial temperature gradient Δα : finite difference between two adjacent scattering angles B Γ : line width of inelastic excitations δ(E): Dirac function ν L : longitudinal kinematic viscosity ρ: density of the system (at the actual R value) ρ w : density of pure water at the corresponding ( ρ,T)-value ρ 0 : 989.8 kg/m 3 (water density at 1 bar and 46.1 °C) 2 χ : chi square distribution χ s,bub : compressibility of the bubble subsystem ω : frequency Ω B : frequency position of inelastic excitations Operators ⊗ : convolution operator