From turtle2@u.washington.edu Tue Jan 6 12:03:27 1998 Received: from jason05.u.washington.edu (root@jason05.u.washington.edu [140.142.78.6]) by lists.u.washington.edu (8.8.4+UW97.07/8.8.4+UW97.05) with ESMTP id MAA31124 for ; Tue, 6 Jan 1998 12:03:26 -0800 Received: from homer06.u.washington.edu (turtle2@homer06.u.washington.edu [140.142.76.13]) by jason05.u.washington.edu (8.8.4+UW97.07/8.8.4+UW97.05) with ESMTP id MAA39786; Tue, 6 Jan 1998 12:03:25 -0800 Received: from localhost (turtle2@localhost) by homer06.u.washington.edu (8.8.4+UW97.07/8.8.4+UW97.04) with SMTP id MAA55450; Tue, 6 Jan 1998 12:03:22 -0800 Date: Tue, 6 Jan 1998 12:03:22 -0800 (PST) From: Lorna Fitzpatrick To: "C.E. Graduate Students" cc: LaDonna Kennedy Subject: Chem E January 12 Seminar (fwd) Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Monday, January 12, 1998 3:30 p.m. Physics-Astronomy Building A110 Molecular Beam Studies of Kinetic Processes in Nanoscale Films of Amorphous Ice Dr. Bruce D. Kay Pacific Northwest National Laboratory Richland, WA ABSTRACT Molecular beam scattering and programmed desorption (both TPD and isothermal) are used to study the adsorption, desorption, and phase transition kinetics of H2O and D2O on multilayer ice surfaces. Two substrates , Au(111) and Ru(0001), are used as templates for the multilayer (5-200) water film growth. Water does not wet Au(111) but is known to form an ice-like bilayer structure on Ru(0001). Below 130K the adsorption probability is unity for both surfaces. Above 130K the desorption rate becomes comparable to the incident beam flux and, as such, the net condensation rate decreases rapidly with increasing temperature. On both substrates water films grown below 130K are initially amorphous in nature but undergo an irreversible phase transformation to a crystalline phase at a rate that is both strongly temperature and thickness dependent. Accompanying this phase transformation the multilayer shows complete isotopic scrambling over a thickness range exceeding 60 layers. The desorption kinetics from both phases are markedly non-zero order and substrate dependent. The experimental results, a quantitative kinetic model, and their implications concerning the utility of nanoscale amorphous films as a model for liquid water will be discussed. University of Washington Department of Chemical Engineering .