Skip to Main content Skip to Navigation
Theses

Collisions moléculaires inélastiques dans l'univers froid
Nouvelles surfaces de potentiel et taux de collision pour CO, HC3N et H2O avec H2 et He

Abstract : WITH THE ADVANCES OF INSTRUMENTS DEDICATED TO MOLECULAR ASTRONOMY MADE DURING THE PAST DECADES AND FORTHCOMING (HERSCHEL AND ALMA), MORE AND MORE MOLECULES ARE DISCOVERED, AND OBSERVED SPECTRA BECOME MORE AND MORE PRECISE. FOR A GOOD UNDERSTANDING OF THESE DATA, ONE NEEDS STATE-TO-STATE COLLISIONAL RATES FOR THE OBSERVED MOLECULES.

THE PRECISION OF RATES IS ONE OF THE KEY POINTS OF THIS THESIS: AT THE SAME TIME, WE SEEK THE MAXIMUM PRECISION AND CHARACTERIZE THE NEED AND COST OF PRECISION IN THE CALCULATIONS WE MAKE. CO-H2 IS A SYSTEM OF GREAT ASTROPHYSICAL INTEREST, PREVIOUSLY WIDELY STUDIED. WE SHOW ON THIS SYSTEM THE EQUAL IMPORTANCE OF THE MAIN STEPS OF THE CALCULATION IN THE FINAL PRECISION OF THE RATES. ON HC3N-H2, WE ACHIEVE FOR THE FIRST TIME A FIT OF THE POTENTIAL ENERGY SURFACE (PES) ON A SPHERICAL BASIS ALLOWING US TO CARRY OUT, ALSO FOR THE FIRST TIME, QUANTUM SCATTERING CALCULATIONS. STRONG QUANTUM SELECTION RULES ARE OBTAINED (ABSENT AT THE CLASSICAL LEVEL). THEY SHOULD PLAY A ROLE IN THE ASTROPHYSICAL MODELING OF THIS MOLECULE. THESE RESULTS ARE IN PRINCIPLE TRANSPOSABLE TO ANY LARGE LINEAR MOLECULE. FINALLY, WE BUILD FOR H2O-H2 A NINE-DIMENSIONAL PES, INCLUDING ALL VIBRATIONS. THE ORIGINAL AND AND PRECISE FIT OF THIS SURFACE ALLOWS US TO RULE ON THE OPTIMAL CHOICE OF GEOMETRIES FOR RIGID MOLECULES, AS WELL AS TO COMPUTE ROVIBRATIONAL RATES. THE LATTER, BEING ONE ORDER OF MAGNITUDE LARGER THAN THE PREVIOUS DATA, WILL CHANGE THE INTERPRETATION OF OBSERVATIONS, NOTABLY THOSE OF THE FORTHCOMING HERSCHEL SPACE TELESCOPE.
Complete list of metadatas

Cited literature [196 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-00102219
Contributor : Michael Wernli <>
Submitted on : Friday, September 29, 2006 - 2:46:41 PM
Last modification on : Friday, November 6, 2020 - 4:01:54 AM
Long-term archiving on: : Thursday, September 20, 2012 - 11:05:46 AM

Identifiers

  • HAL Id : tel-00102219, version 1

Collections

UJF | CNRS | INSU | LAOG | OSUG | UGA

Citation

Michael Wernli. Collisions moléculaires inélastiques dans l'univers froid
Nouvelles surfaces de potentiel et taux de collision pour CO, HC3N et H2O avec H2 et He. Astrophysique [astro-ph]. Université Joseph-Fourier - Grenoble I, 2006. Français. ⟨tel-00102219⟩

Share

Metrics

Record views

380

Files downloads

1422