A5074933641- Advanced Chemical Physics Studies
- Spectroscopy and Laser Applications
- Quantum, superfluid, helium dynamics
- Atmospheric Ozone and Climate
- Atmospheric chemistry and aerosols
- Catalytic Processes in Materials Science
- Air Quality Monitoring and Forecasting
- Atmospheric and Environmental Gas Dynamics
- Air Quality and Health Impacts
- Atomic and Subatomic Physics Research
- Marine and coastal ecosystems
- Spectroscopy and Quantum Chemical Studies
- Ammonia Synthesis and Nitrogen Reduction
- Water Quality Monitoring and Analysis
- Catalysis and Oxidation Reactions
- nanoparticles nucleation surface interactions
Swiss Federal Laboratories for Materials Science and Technology
2017-2018
École Polytechnique Fédérale de Lausanne
2011-2017
Vibrating Water Apart The main route for producing hydrogen industrial chemical synthesis is steam reforming, in which water and methane react at high temperatures on nickel catalysts to produce carbon dioxide. For both methane, the initial dissociation step can be promoted by translational energy of a molecule as well its internal vibrational energy, fundamental studies these reactions try determine relative contributions pathways. Although reaction has been studied, only recently have...
We present a stereodynamics study of the dissociative chemisorption vibrationally excited methane on (100), (110), and (111) planes nickel single crystal surface. Using linearly polarized infrared excitation antisymmetric C–H stretch normal mode vibration (ν3), we aligned angular momentum amplitude CH4(ν3) in laboratory frame measured alignment dependence state-resolved reactivity CH4 for ν3 = 1, J 0–3 quantum states over range incident translational energies. For all three surfaces studied,...
Highly efficient preparation of molecules in a specific rovibrationally excited state for gas/surface reactivity measurements is achieved molecular beam using tunable infrared (IR) radiation from single mode continuous wave optical parametric oscillator (cw-OPO). We demonstrate that with appropriate focusing the IR radiation, crossing fixed frequency field experience Doppler tuning can be adjusted to achieve complete population inversion two-level system by rapid adiabatic passage (RAP). A...
Infrared laser excitation of partially deuterated methanes (CH3D and CH2D2) in a molecular beam is used to control their dissociative chemisorption on Pt(111) single crystal determine the quantum state-resolved dissociation probabilities. The exclusive detection C-H cleavage products adsorbed surface by infrared absorption reflection spectroscopy indicates strong bond selectivity for both methane isotopologues upon stretch excitation. Furthermore, observed be mode-specific. Excitation...
Quantum state-resolved reactivity measurements probe the role of vibrational symmetry on activation dissociative chemisorption CH4 Pt(111). IR-IR double resonance excitation in a molecular beam is used to prepare all three different components A1, E, and F2 2ν3 antisymmetric stretch overtone vibration. Methyl dissociation products chemisorbed cold Pt(111) surface are detected via reflection absorption infrared spectroscopy (RAIRS). We observe similar for prepared A1 sublevels but up factor 2...
The present study measures the sticking probability of heavy water (D(2)O) on H(2)O- and D(2)O-ice probes influence selective OD-stretch excitation D(2)O these ices. Molecular beam techniques are combined with infrared laser to allow for precise control incident angle, translational energy, vibrational state molecules. For a energy 69 kJ/mol large angles (θ ≥ 45°), H(2)O-ice was found be 1% lower than D(2)O-ice. by IR pumping molecules produces no detectable change (<10(-3)). results...
Abstract. Detailed knowledge about the urban NO2 concentration field is a key element for obtaining accurate pollution maps and individual exposure estimates. These are required improving understanding of impact ambient on human health related air quality measures. However, city-scale with high spatio-temporal resolution still lacking, mainly due to difficulty measurement at sub-ppb level precision. We contribute close this gap through development compact instrument based mid-infrared laser...
Quantum state resolved reactivity measurements probe the role of vibrational symmetry on activation dissociative chemisorption CH4 Ni(111). IR-IR double resonance excitation in a molecular beam was used to prepare three different components, A1, E, and F2, 2ν3 antisymmetric stretch overtone vibration as well ν1+ν3 symmetric plus C–H combination band F2 symmetry. The quantum specific dissociation probability S0 (sticking coefficient) measured for each four states by detecting chemisorbed...
Abstract. Detailed knowledge about the urban NO2 concentration field is a key element for obtaining accurate, individual exposure estimates. These are required improving understanding of impact ambient on human health and related air quality measures. We developed compact robust quantum cascade laser absorption spectrometer (QCLAS) deployed it tram in city Zurich (Switzerland) to perform mobile real-time measurements NO2. Thorough analysis obtained data, instance by comparison with data from...
Keywords: Water ; methane chemisorption double-resonance RAIRS state resolved reactivity Ni(111) Pt(111) ice surface science mode specificity bond selectivity These Ecole polytechnique federale de Lausanne EPFL, n° 6061 (2014)Programme doctoral Chimie et Genie chimiqueFaculte des sciences baseInstitut ingenierie chimiquesLaboratoire chimie physique moleculaireJury: Prof. J. Vanicek (president du jury), R. Beck (directeur these), A. Hodgson, Osterwalder, Wodtke (rapporteurs) Public defense:...