1. INVESTIGATION OF VAN DER WAALS COMPLEXES IN A FREE EXPANSION OF C 2 H 2 /X (X=RARE GAS) (X=Rg) USING CW CAVITY RING-DOWN SPECTROSCOPY IN THE OVERTONE RANGE

2. Summary Introduction The Fantasio set-up Challenge(s) Results!!! Next?

3. Introduction In practice  De C 2 H 2 -Ne C 2 H 2 -Ar C 2 H 2 -Kr A priori ordering in the interaction energy

4. Introduction In practice  De C 2 H 2 -Ne C 2 H 2 -Ar C 2 H 2 -Kr Initial experiment Should be observed but expensive Less rigid Too expensive Ordering a priori in the interaction energy

5. Introduction In practice (Literature)  De C 2 H 2 -Ne C 2 H 2 -Ar C 2 H 2 -Kr Ordering a priori in the interaction energy C2H2C2H2 MWIRNI NeXX ArXXX KrNEVER REPORTED

6. Introduction  De C 2 H 2 -Ne C 2 H 2 -Ar C 2 H 2 -Kr Ordering a priori in the interaction energy Milce et al, Chem. Phys. Letters, 250 (1996) 95 In practice (Literature) C2H2C2H2 MWIRNI NeXX ArXXX KrNEVER REPORTED

7. Introduction In practice  De C 2 H 2 -Ne C 2 H 2 -Ar C 2 H 2 -Kr Ordering a priori in the interaction energy Milce et al, Chem. Phys. Letters, 250 (1996) 95 C2H2C2H2 MWIRNI NeXX ArXXX KrNEVER REPORTED

8. “Fourier trANsform, Tunable diode and quadrupole mAss spectrometers interfaced to a Supersonic expansIOn” FANTASIO set-up Main features 1 Roots primary pump 2 Turbomolecular pumps 3200CT Continuous supersonic expansion Probes: Cavity ringdown spectroscopy Mass spectrometry FTIR

9. cavity output mirror cavity input mirror detection system h h Gaz

10. cavity output mirror cavity input mirror detection system I t =I threshold time (  s) (1/e)I t I  onoff h h Gaz

11. cavity output mirror cavity input mirror detection system I t =I threshold time (  s) (1/e)I t I  onoff R = 99.999%   ~ 120  s 650m under 1 cm long slit h h Gaz

12. Challenge(s) Hitran simulation of C 2 H 2 absorption spectrum Wavenumber (cm -1 )

13. Challenge(s) Wavenumber (cm -1 ) Hitran simulation of C 2 H 2 absorption spectrum 2CH 1 + 3

14. 2CH 1 + 3 1CH  3 Challenge(s) Interaction energy of C 2 H 2 -Ar Hitran simulation of C 2 H 2 absorption spectrum Wavenumber (cm -1 )

15. 2CH 1 + 3 1CH  3 Interaction energy of C 2 H 2 -Ar Wavenumber (cm -1 ) Result (1) C 2 H 2 -Ar EXPANSION of 1% C 2 H 2 in Ar Hitran simulation of C 2 H 2 absorption spectrum

16. 2CH 1 + 3 1CH  3 Result (1) C 2 H 2 -Ar Interaction energy of C 2 H 2 -Ar Wavenumber (cm -1 ) EXPANSION of 1% C 2 H 2 in Ar Hitran simulation of C 2 H 2 absorption spectrum

17. 2CH 1 + 3 1CH  3 Result (1) C 2 H 2 -Ar Interaction energy of C 2 H 2 -Ar Wavenumber (cm -1 ) ZOOM 100X a lot of work EXPANSION of 1% C 2 H 2 in Ar Hitran simulation of C 2 H 2 absorption spectrum

18. 2CH 1 + 3 1CH  3 Result (1) C 2 H 2 -Ar Interaction energy of C 2 H 2 -Ar Wavenumber (cm -1 ) ZOOM 100X a lot of work EXPANSION of 1% C 2 H 2 in Ar Hitran simulation of C 2 H 2 absorption spectrum

19. T rotational =9 K Result (1) C 2 H 2 -Ar Lauzin et al, J.Phys.Chem A,1113 (2009) 2361

20. Result (2) C 2 H 2 -Kr  De C 2 H 2 -Ne C 2 H 2 -Ar C 2 H 2 -Kr

21. Result (2) C 2 H 2 -Kr  De C 2 H 2 -Ne C 2 H 2 -Ar C 2 H 2 -Kr Wavenumber (cm -1 )

22. Result (2) C 2 H 2 -Kr EXPANSION: 99% Ar + 1% C 2 H 2  De C 2 H 2 -Ne C 2 H 2 -Ar C 2 H 2 -Kr Wavenumber (cm -1 )

23. Result (2) C 2 H 2 -Kr EXPANSION: 88% Ar + 1% C 2 H 2 AND 11% Kr  De C 2 H 2 -Ne C 2 H 2 -Ar C 2 H 2 -Kr Wavenumber (cm -1 )

24. Result (2) C 2 H 2 -Kr EXP. SPECTRUM SIMULATION C 2 H 2 -Kr EXPANSION: 88% Ar + 1% C 2 H 2 AND 11% Kr PGOPHER SOFTWARE (COLIN WESTERN) Wavenumber (cm -1 )

25. Result (2) C 2 H 2 -Kr EXP. SPECTRUM SIMULATION C 2 H 2 -Kr EXPANSION: 88% Ar + 1% C 2 H 2 AND 11% Kr PGOPHER SOFTWARE (COLIN WESTERN) Wavenumber (cm -1 ) FIRST DETECTION

26. Result (2) C 2 H 2 -Kr SIMULATION C 2 H 2 -Kr SIMULATION C 2 H 2 -Ar EXPANSION: 88% Ar + 1% C 2 H 2 AND 11% Kr PGOPHER SOFTWARE (COLIN WESTERN) Wavenumber (cm -1 ) EXP. SPECTRUM FIRST DETECTION

27. Result (2) C 2 H 2 -Kr SIMULATION C 2 H 2 -Kr SIMULATION BOTH CONTRIBUTIONS EXPANSION: 88% Ar + 1% C 2 H 2 AND 11% Kr FIRST DETECTION PGOPHER SOFTWARE (COLIN WESTERN) Wavenumber (cm -1 ) SIMULATION C 2 H 2 -Ar EXP. SPECTRUM

28. Result (3) C 2 H 2 -Ne NO SIGNAL  EXPANSION C 2 H 2 IN Ne

29. Result (3) C 2 H 2 -Ne NO SIGNAL  Increase pressure ratio Decrease slit width EXPANSION C 2 H 2 IN Ne

30. Result (3) C 2 H 2 -Ne NO SIGNAL  EXPANSION C 2 H 2 IN Ne Increase pressure ratio Decrease slit width

31. Result (3) C 2 H 2 -Ne NO SIGNAL  Cooling of the slit EXPANSION C 2 H 2 IN Ne Increase pressure ratio Decrease slit width

32. Result (3) C 2 H 2 -Ne  De C 2 H 2 -Ne C 2 H 2 -Ar C 2 H 2 -Kr Wavenumber (cm -1 )

33. Result (3) C 2 H 2 -Ne - 4°C 30°C Wavenumber (cm -1 ) Slit temperature

34. Result (3) C 2 H 2 -Ne ZOOM 5X - 4°C 30°C Wavenumber (cm -1 ) Slit temperature

35. Result (3) C 2 H 2 -Ne C 2 H 2 -Ne Bemish et al J.Chem.Phys,109 (1998) 8970 C 2 H 2 -Ne?

36. Result (3) C 2 H 2 -Ne Bemish et al J.Chem.Phys,109 (1998) 8970 C 2 H 2 -Ne C 2 H 2 -Ne?

37. Result (3) C 2 H 2 -Ne Bemish et al J.Chem.Phys,109 (1998) 8970 C 2 H 2 -Ne C 2 H 2 -Ne? YESSSSSSSSSSSSSS

38. Perspectives Experimental

39. Perspectives Experimental PULSED EXPANSION

40. Perspectives Experimental PULSED EXPANSION Theory Quit the rigid approach And solve numerically This problem

41. Perspectives Experimental PULSED EXPANSION Theory Quit the rigid approach And solve numerically This problem NEXT TALK

42. ACKNOWLEDGEMENTS Peter Macko Jean Vander Auwera Athena Rizopoulos Baris Kizil Patrick Van Poucke And you for your attention…

45. Result (3) C 2 H 2 -Ne ZOOM 5X - 4°C 30°C Wavenumber (cm -1 ) Slit temperature 6556.46496