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

? ? * * 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

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

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

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?

LA-CP-FTMW spectrometer LASER Nd-YAG *

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

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

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

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

Lactaldehyde dimeric form: µ=0 µ=0

Lactaldehyde dimeric form: MP2/6-311++g(d,p)

The rotational spectrum * DIMERIC FORM

The rotational spectrum DIMER 1 A/MHz: 2007.94052( 58) B/MHz: 1155.16487( 38) C/MHz: 866.77727(31) - Very intense b-type transitions - Intense c-type lines transitions

The rotational spectrum DIMER 2 A/MHz: 1996.16046(68) B/MHz: 1165.56439(40) C/MHz: 850.74327(30) - Weak c-type transitions - Very weak b-type transitions DIMER 1 A/MHz: 2007.94052( 58) B/MHz: 1155.16487( 38) C/MHz: 866.77727(31) - Very intense b-type transitions - Intense c-type lines transitions

Dimeric form characterization: MP2/6-311++g(d,p)

Dimeric form characterization: MP2/6-311++g(d,p) 55 transitions measured 44 transitions measured

Dimeric form characterization: CONFORMER III

Dimeric form characterization: MP2/6-311++g(d,p)

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

Monomeric form characterization: MP2/6-311++g(d,p)

Monomeric form characterization: DIMERIC FORM * MONOMERIC FORM

Monomeric form characterization: MP2/6-311++g(d,p) DIMERIC FORM * MONOMERIC FORM 21 transitions measured

Lactaldehyde caught in the gas phase:

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.

Molecular Astrophysics Universidad de Valladolid Acknowledgements Finantial support (FP/2007-2013) / ERC-2013-SyG Grant No. 610256 CSD 2009-00038 Molecular Astrophysics Grants: CTQ 2013- 40717-P CTQ 2016- 76393- P Grants: VA175U13 VA077U16 Pr. José L. Alonso GEM , Edificio Quifima, Unidad Asociada CSIC, Universidad de Valladolid Valladolid, Spain