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Table of contents
1 Theoretical background
1.1 Surface Physics
1.1.1 Sub-monolayer and multilayer: surface and bulk
1.1.2 Adsorption
1.1.2.1 Physisorption and chemisorption
1.1.2.2 Sticking
1.1.3 Desorption
1.1.3.1 Thermal desorption
1.1.3.2 Non-thermal desorption
1.1.4 Surface migration: Thermal hopping and tunneling
1.1.4.1 An evaluation of the crossover temperature Ttnth.
1.2 Gas Phase Chemistry
1.2.1 Chemistry in the gas phase
1.2.2 Exothermic and endothermic reactions
1.3 Surface Chemistry
1.3.1 Eley-Rideal mechanism
1.3.2 Langumuir-Hinshelwood
1.3.3 Hot atom mechanism
2 Experimental apparatus and methods
2.1 Experimental apparatus
2.1.1 The main chamber
2.1.2 The beamlines
2.1.3 The microwave cavities
2.1.4 The sample holder and the sample
2.1.5 The Quadrupole Mass Spectrometer
2.1.6 The Infrared Spectrometer
2.2 Experimental methods
2.2.1 Water ice deposition on the sample holder
2.2.2 Mass spectroscopy: the dierent uses of the QMS
2.2.2.1 Cracking pattern
2.2.2.2 Residual gas analyzer: knowing beam composition
2.2.2.3 Knowing electronic state of atoms and molecules
2.2.2.4 TPD: Temperature Programmed Desorption
2.2.2.5 DED: During-Exposure Desorption
2.2.3 Calibration of the H2 and D2 beams
2.2.4 Calibration of the molecular beams
2.2.4.1 Determination of O3 monolayer and detection eciency .
2.2.5 Can reactions occur on gas phase?
3 Model
3.1 Model
3.1.1 Initial condition
3.1.2 Flux: x
3.1.3 Reaction probability: r
3.1.4 Diusion coecient: kdiff
3.1.5 Desorption coecient: Nxdes
3.1.6 Conclusion
3.2 From model parameters to physical-chemical quantities
3.2.1 Reactivity: reaction probability and activation barrier
3.2.1.1 Teff evaluation
3.2.2 Mobility: kdiff and surface migration
3.2.3 Desorption: desorption probability and binding energy
4 Surface Physics
4.1 Oxygen reactivity and diusion
4.1.1 Experimental
4.1.2 Oxygen reactivity
4.1.3 Oxygen diusion
4.1.3.1 The role of substrate
4.1.3.2 Model
4.1.3.3 Armophicity and diusion
4.2 Evaluation of desorption energies
4.2.1 Desorption energy of non-reactive species
4.2.2 Desorption energy of reactive species
4.2.3 Conclusion
4.3 Chemical desorption
4.3.1 The chemical desorption of the O-H system
4.3.1.1 Chemical desorption in O2+H experiments
4.3.1.2 Chemical desorption in O3+H experiments
4.3.1.3 Chemical desorption in O+H experiments
4.3.2 The inuence of the substrate: CD of O2
4.3.2.1 Experimental results
4.3.2.2 Model and discussion
4.3.3 Conclusion
5 Surface Chemistry
5.1 Water formation via O2+H(D)
5.1.1 Experimental
5.1.2 Results and discussion
5.2 Nitrogen oxides chemistry
5.2.1 NO+O2
5.2.1.1 Experimental
5.2.1.2 Result and discussion
5.2.1.2.a Initial conditions and model
5.2.2 NO+O3
5.2.2.1 Experimental
5.2.2.2 Results and discussion
5.2.3 NO+O
5.2.3.1 Experimental
5.2.3.2 Results and discussion
5.2.3.2.a Dependence on surface temperature
5.2.4 NO2 reactivity
5.2.5 Conclusion
5.3 O/C/H chemistry
5.3.1 Carbon dioxide formation on cold surfaces
5.3.1.1 CO+O
5.3.1.1.a Experimental
5.3.1.1.b Results and discussion
5.3.1.1.c Model: evaluation of the CO+O barrier
5.3.1.1.d Conclusions
5.3.1.2 H2CO+O
5.3.1.2.a Experimental
5.3.1.2.b Results and discussion
5.3.1.2.c Model: evaluation of the H2CO+O barrier
5.3.1.3 Conclusion
5.3.2 The cycle of the CO-H chemistry
5.3.2.1 CO+H
5.3.2.2 H2CO+H
5.3.2.3 Chemical desorption pumping process
5.3.3 Preliminary results of CH3OH and HCOOH irradiation with H/O atoms
6 Conclusion
6.1 Astrophysical conclusion
6.1.1 Astrophysical context
6.1.2 O diusion
6.1.3 Chemical Desorption
6.1.4 H/C/N/O chemical network
6.1.4.1 Interstellar ices
6.2 Perspectives
6.2.1 Ice growth: MonteCarlo Model
6.2.2 Further perspectives
Appendix A: atomic and molecular term symbols
Appendix B: list of publications
List of Acronyms
Acknowledgements
Remerciements
