#################################################### # Laurent Menard # requesting 5 days, at minimum=4 days # beamline 33BM, EXAFS of supported Au catalysts with Self-Assembled Monolayer surface probes # instrument 33BM-B XAFS #################################################### # top:/home/www/beamtime-requests/req01014.txt # UNICAT Member Beam Time Request #1014 # created Mon Jul 31 10:45:45 CDT 2006 #################################################### apsrun: 2006-02 beamline: 33BM collaboration: No collaborator_Jenia: ON collaborator_Paul: ON contact: lmenard@uiuc.edu days: 5 description: Gold catalysts consisting of Au nanoparticles supported on TiO2 supports will be studied using XANES and EXAFS. The samples will consist of a series of supported particles with progressively larger average particle sizes which will have been investigated for their catalytic activities. EXAFS will be used as a structural probe to determine a model of nanoparticle shape. This model will be supported through advanced electron microscopy methods but will also be a model that is more rigorously verified by EXAFS alone than is typically possible by using self-assembled monolayers to probe the number of surface atoms. This will be achieved by measuring the clean catalysts and a portion of each sample that has had thiols deposited on the gold from an ethanolic solution (done at UIUC, not APS). Our prior work has established the bonding motifs of thiols on small gold nanoparticles (Menard et al., J. Phys. Chem. B, ACS ASAP) allowing Au-S coordination number to serve as a probe for the number of surface sites. The differing functional dependencies on nanoparticle size of the number of surface atoms and the bulk Au-Au coordination numbers from multiple single-scattering distances (1st through 4th or 5th nearest neighbor) will provide a self-contained (to the single XAS technique) and strict set of limits to the structural model. equipment_required: Ion chambers, fluorescence detector, liquid nitrogen. experiment: EXAFS of supported Au catalysts with Self-Assembled Monolayer surface probes foreign_nationals: Joo Kang hazards: No wet chemistry will be performed at APS. Samples are not toxic. Liquid nitrogen will be used to make measurements at cryogenic temperatures to increase signal-to-noise ratio. instrument: 33BM-B XAFS instrument_other: minimumdays: 4 name: Laurent Menard nonmembers: Joo Kang submit: Submit unacceptable_dates: Month of December (I will be finishing with my thesis and defending). z34ID_details: #REMOTE_HOST: menard-m.mrl.uiuc.edu #REMOTE_ADDR: 130.126.101.231 #CONTENT_LENGTH: 2102 #HTTP_REFERER: http://www.uni.aps.anl.gov/admin/unireq.html #HTTP_USER_AGENT: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)