Sum frequency generation study of CO adsorbed on palladium single crystal and nanoparticles : adsorption and catalytic oxidation as a function of size
type: Dataset
description: The CO reaction on metals is of great interest experimentally and theoretically because it serves as a model system to understand molecular chemisorption and catalyzed reactions on metals. This thesis aims at progressing along the general trends of surface science: bridging the pressure and material gaps in the study of catalysts. Sum Frequency Generation (SFG) is at the heart of this work. It involves a nonlinear optical process with an IR pulse induced coherent first-order polarization up-converted by a visible pulse into a second-order polarization at the sum frequency. In this thesis it is used to record CO vibrational spectra on the Pd nanoparticles (NP)/MgO/Ag(100) to understand the adsorption and oxidation thanks to its specific advantages in surface science: sensitivity and surface selectivity. The questions proposed are the possible roles of the adsorption sites which only exist on the NPs, the effect of the size of NPs and the presence of oxygen on the CO adsorption and catalytic reactivity, the effect of adsorption of oxygen (from ‘normal’ – dissociative chemisorption to ‘sub-surface’), the variation of reactivity of CO in the different sites when pressure and temperature increase. (1) We have studied CO adsorption on Pd(100) as a reference. Below a CO coverage of 0.5 ML SFG results confirm previous IRAS studies. Above 0.5 ML, we have observed in much more details than previously two vibrational bands assigned to CO at compressed and uncompressed bridge sites, of which we have measured the frequency and intensity and the decoherence time T₂ as a function of coverage. (2) Pd NP size effect on CO adsorption is studied (from Pd(100) to particles with about 300 atoms). At pressures below 10⁻³ mbar the CO spectra on a coalesced layer and on large NPs are dominated by the same bridge band as on Pd(100). The CO singleton frequency decreases with coverage, revealing the evolution of chemisorption with size. DFT calculations done at ENS Lyon reveal that the main m…
identifier: NNT: 2013PA112343
issued: 2026-05-07T08:16:27.035414
language: en
modified: 2026-05-07T08:16:27.035419
contact point: Organization
  fn: CCSD
keyword: adsorption
keyword: adsorption-sites
keyword: catalyse
keyword: catalysis
keyword: chimothechemical-sciencesother
keyword: co
keyword: effets-de-taille
keyword: generation-de-somme-de-frequences-sfg
keyword: infoeu-reposemanticsdoctoralthesis
keyword: nanoparticle
keyword: nanoparticule
keyword: oxidation
keyword: oxydation
keyword: physcondcm-genphysics-physicscondensed-matter-cond-matother-cond-matother
keyword: sites-dadsorption
keyword: size-effects
keyword: spectro-temporal
keyword: spectro-temporel
keyword: sum-frequency-generation-sfg
keyword: theses
landing page: https://theses.hal.science/tel-00933675

Sum frequency generation study of CO adsorbed on palladium single crystal and nanoparticles : adsorption and catalytic oxidation as a function of size
type: Distribution
format: HTML
issued: 2026-05-07T08:16:27.040067
modified: 2026-05-07T08:16:27.016599
access URL: https://theses.hal.science/tel-00933675

test_moissonnage_selune
type: Agent