1. The microwave spectrum of lactaldehyde, the simplest chiral sugar.
E.R. ALONSO, L. KOLESNIKOVÁ, CARLOS CABEZAS, SANTIAGO MATA, J.C. GUILLEMIN, J.L. ALONSO
Urbana-Champaign
June 2017

2. ? ? * * Sugars in space: GLYCOLALDEHYDE Detected (Hollis et al. 2000)
GLYCERALDEHYDE
Non Detected
(Lovas et al. 2003)
GLYCOLALDEHYDE
Detected
(Hollis et al. 2000) ? ? *
LACTALDEHYDE
Non data available

3. LACTALDEHYDE, EVIDENCES OF POSSIBLE CANDIDATE TO BE PRESENT IN THE ISMS
Marcellus et al. PNAS, 2015, 112(4) | 965–970
LACTALDEHYDE

4. WHY IS THERE NO DATA OF LACTALDEHYDE?
DIMERIZATION
LACTALDEHYDE
HYDROXYACETONE
THERMODYNAMICALLY MORE STABLE ISOMER

5. STANDARD HEATING METHODS
HOW COULD WE BREAK FREE THE LACTALDEHYDE IN GAS PHASE?
STANDARD HEATING METHODS
HYDROXYACETONE
THERMODYNAMICALLY MORE STABLE ISOMER
LASER ABLATION *
Could the laser ablation produce dedimerization?

6. LA-CP-FTMW spectrometer
LASER Nd-YAG *

7. LA-CP-FTMW spectrometer
Gas pulse
Jet Ne
Laser pulse
Rotary
Diffusion
pump
Nd:YAG laser

8. LA-CP-FTMW spectrometer
Gas pulse
MW field
Polarization Ne
Laser pulse
Chirped MW pulse
Rotary
Diffusion
pump

9. LA-CP-FTMW spectrometer
Gas pulse
Molecular emission Ne
Laser pulse
Chirped MW pulse
Rotary
Diffusion
pump
Detection
Detection
Frequency-domain
Time-domain FT

10. The rotational spectrum
6-18GHz
23k acq
Try to identify possible lines of the lactaldehyde dimeric form conformers

11. Lactaldehyde dimeric form:
µ=0
µ=0

12. Lactaldehyde dimeric form:
MP2/ g(d,p)

13. The rotational spectrum*
DIMERIC FORM

14. The rotational spectrum
DIMER 1
A/MHz: ( 58)
B/MHz: ( 38)
C/MHz: (31)
- Very intense b-type transitions
- Intense c-type lines transitions

15. The rotational spectrum
DIMER 2
A/MHz: (68)
B/MHz: (40)
C/MHz: (30)
- Weak c-type transitions
- Very weak b-type transitions
DIMER 1
A/MHz: ( 58)
B/MHz: ( 38)
C/MHz: (31)
- Very intense b-type transitions
- Intense c-type lines transitions

16. Dimeric form characterization:
MP2/ g(d,p)

17. Dimeric form characterization:
MP2/ g(d,p)
55 transitions
measured
44 transitions
measured

18. Dimeric form characterization:
CONFORMER III

19. Dimeric form characterization:
MP2/ g(d,p)

20. Look for lines of the lactaldehyde monomeric form
Monomeric form characterization:
Look for lines of the lactaldehyde monomeric form *
DIMERIC FORM

21. Monomeric form characterization:
MP2/ g(d,p)

22. Monomeric form characterization:
DIMERIC FORM *
MONOMERIC FORM

23. Monomeric form characterization:
MP2/ g(d,p)
DIMERIC FORM *
MONOMERIC FORM
21 transitions measured

24. Lactaldehyde caught in the gas phase:

25. What comes next? Until now: Next step:
Characterization of the more stable monomeric form of lactaldehyde in gas phase
Characterization of the more stable dimeric forms of lactaldehyde in gas phase
Microwave spectrum recorded within 6-18GHz
Next step:
Extend the measurements up to 40GHz.

26. Molecular Astrophysics Universidad de Valladolid
Acknowledgements
Finantial support
(FP/ ) / ERC-2013-SyG
Grant No
CSD
Molecular Astrophysics
Grants: CTQ P
CTQ P
Grants: VA175U13
VA077U16
Pr. José L. Alonso
GEM , Edificio Quifima, Unidad Asociada CSIC,
Universidad de Valladolid
Valladolid, Spain