1. The Microwave Spectrum of the HCOOCD 2 H species of Methyl Formate L. H. Coudert, a T. R. Huet, b L. Margulès, b R. Motyenko, b and H. Møllendal c a LISA, CNRS/Universités Paris Est et Denis Diderot, Créteil, France b PhLAM, CNRS/Université de Lille I, Villeneuve d’Ascq, France c CTCC, University of Oslo, Blindern, Norway

2. Doubly deuterated methyl formate Important from the astrophysical point of view. 1 Measuring the [D]/[H] ratio. Internal rotation of a CD 2 H group. 1. Churchwell and Winnewisser, A&A 45 (1975) 229

3. Overview The PEF of the isotopic species Tunneling patterns The available data Analysis results K-type doubling & tunneling interaction Hyperfine structure

4. The PEF of HCOOCH 3 Ilyushin, Kryvda, and Alekseev, J. Mol. Spec. 255 (2009) 32 V   cm  V   cm  

5. The PEF of HCOOCH 2 D Liu and Quade, J. Mol. Spec. 146 (1991) 252 10 cm  1 V 1  ZPE Effects 

6. The PEF of HCOOCD 2 H Liu and Quade, J. Mol. Spec. 146 (1991) 252 10 cm  1 V 1  ZPE Effects 

7.  eq  H-in plane configuration  eq  H-out of plane configuration  eq  H-out of plane configuration The 3 equilibrium configurations Tunneling motion

8. HCOOCH 3 405 1 HCOOCH 2 D 10 cm  1 84.8 2 1. Ilyushin, Kryvda, and Alekseev, J. Mol. Spec. 255 (2009) 32 2. Margulès et al., J. Mol. Spec. 254 (2009) 55 3. This work Tunneling patterns HCOOCD 2 H 10 cm  1 10.6 3

9. The measurements 6126 microwave transitions measured in Lille Experimental uncertainty is  MHz

10. Analysis results H-in plane configuration: Watson-type Hamiltonian H-out of plane configuration: Water dimer formalism 1,2 1. Hougen, J. Mol. Spec. 114 (1985) 395 & Coudert and Hougen, J. Mol. Spec. 130 (1988) 86 2. Margulès et al., J. Mol. Spec. 254 (2009) 55

11. K-type doubling & tunneling Regular K-type doubling

12. K-type doubling & tunneling

13. Quartet transitions Regular transition Tunneling effects are the largest K-type doubling is dominant  quartet transitions assigned for the H-out of plane configuration

14. Quadrupole coupling Hyperfine Structure Averaging effects for the H-out of plane configuration. Hyperfine structure could be experimentally resolved

15. Hyperfine Structure H-in plane configuration Doppler doubling = 62 kHz HWHH = 1.8 kHz

16. Hyperfine Structure H-in plane configuration

17. Hyperfine Structure H-out of plane configuration Doppler doubling = 54 kHz HWHH = 1.2 kHz Doppler doubling = 50 kHz HWHH = 1.2 kHz

18. Hyperfine Structure H-out of plane configuration