Microwave Studies of Glycerol F.J. Lovas, and D.F Plusquellic NIST and V.V. Ilyushin and R.A. Motiyenko Institute of Radio Astronomy of NASU

Outline Background on Studies of Polyols (for astronomy) MW Study of Glycerol: ab Initio calculations Prior free jet study ( GHz) FTMW study ( GHz) Summary

Glycerol: CH 2 OHCHOHCH 2 OH Sweet, colorless, viscous liquid Results from hydrolysis of fats & oils Many applications: pharmaceuticals & cosmetics chemical stabilizer plasticizer coatings moisturizer adhesives & lubricants

Sugars and Polyols in Space C 2 sugar: “Interstellar Glycolaldehyde: The First Sugar” J.M. Hollis, F.J. Lovas, & P.R. Jewell, Ap. J. 540, L107 (2000) “Green Bank Telescope Observation of Glycolaldehyde” Hollis, Jewell, Lovas & Remijan, ApJ 613, L45 (2004) C 2 sugar alcohol: “Interstellar Antifreeze: Ethylene Glycol” Hollis, Lovas, Jewell, & Coudert, Ap. J. 571, L59 (2002) “Ethylene glycol in comet C/1995 O1 (Hale-Bopp)” Crovisier, et al. Astron. Astrophys. 418, L35 (2004). C 3 sugars: “GBT Detection of New Interstellar Aldehydes: Propenal and Propanal” Hollis, Jewell, Lovas, Remijan & Møllendal, Ap. J. 610, L21 (2004). Negative result on glyceraldehyde, C 3 H 6 O 3

Sugars and Polyols in Space C 3 sugars: “1,3-Dihydroxyacetone in Sgr B2(N-LMH): The First Interstellar Ketose” S.L. Widicus Weaver & G.A. Blake Ap. J. 624, L33 (2005); erratum Ap. J. 632, Li63 (2005) “Investigating the Limits of Chemical Complexity in Sagittarius B2(N): A Rigorous Attempt to confirm 1,3-dihydroxyacetone” Apponi, Halfen, Ziurys, Hollis, Remijan & Lovas Ap. J. 643, L29 (2006) 63 new transitions of DHA were sought but no plausible emission was observed for 97% of these

Murchison and Murray Meteorite Studies Polyols in Meteorites by GC-MS Carbonaceous meteorites as a source of sugar-related organic compounds for the early Earth“ Cooper, Kimmich, Belisle, Sarinana, Brabham & Garrel, Nature 414, 879 (2001). “Murchison meteorite is generally used as the standard reference for organic compounds in Extraterrestrial material.” CarbonsSugarsSugar AlcoholsSugar Acids C2C2 ---ethylene glycol ---- C3C3 dihydroxyacetoneglycerolglyceric acid C4C4 ---Erythritol & Threitol erythronic acid & threonic acid C5C5 ---ribitol & isomers ribonic acid & isomers

Prior Lab and Theoretical Studies Ab Initio study of ethylene glycol and glycerol: Teppen et al. J. Mol. Struct. 314, 169 (1994). Found 11 stable conformers for glycerol “Free jet investigation of the rotational spectrum of glycerol” G. Maccaferri, W. Caminati, & P.G. Favero, J. Chem. Soc. Faraday Trans. 93, 4115 (1997). Identified the 2 lowest energy conformers in the 60 – 78 GHz range for the normal and tri-OD species

(1) G'Gg'gg' E = 0.0 cm -1 (2) GGtg'g' E = 34.4 cm -1 (3) GGgg'g' E = cm -1 (4) G'Gg'gt E = cm -1 (5) GG'tg'g E = cm -1 Five lowest energy conformers of glycerol and their relative energies from ab initio MP2 aug-cc-pVTZ basis set with zero point corrections

NIST Mini-FTMW Spectrometer

Mirror-Mounted Heated Reservoir Nozzle

A1 A2 Conformer 1 Conformer 2 Conformer 5 a-type * * * C1 B1 B2

ParameterG'Gg'gg' (1) ab initio MP2 GGtg'g' (2) ab initio MP2 Another Conformer like (2)? A (MHz) (11) % (19) % (13) B (MHz) (94) % (96) % (79) C (MHz) (96) % (84) % (76) Δ J (kHz)1.4863(18)0.5251(10)0.5004(80) Δ JK (kHz)1.5133(52)0.1784(32)0.172(35) Δ K (kHz)2.8869(42)7.520(16)7.97(28) δ J (kHz) (93) (34)0.0367(45) δ K (kHz)0.9786(57)-0.649(14)-0.97(35) N lines rms (MHz) Energy (cm -1 ) Two Lowest Energy Conformers of Glycerol C1

ParameterGGgg'g' (3)ab initio MP2 A (MHz) (16) % B (MHz) (40) % C (MHz) (46) % Δ J (kHz)0.5208(44) Δ JK (kHz)0.138(26) Δ K (kHz)8.02(37) δ J (kHz)0.0303(17) δ K (kHz)-0.48(14) N lines 30 rms (MHz) Energy (cm -1 )207.6 New Conformer (3) at 207 cm -1 C1

Parameter GG'tg'g (5) v=0 GG'tg'g (5) v=1 ab initio MP2 A (MHz) (28) (28) % B (MHz) (71) (72) % C (MHz) (76) (75) % Δ J (kHz) (74) (74) Δ JK (kHz)2.4295(34)2.4354(32) Δ K (kHz)8.406(38)8.415(38) δ J (kHz) (16) (16) δ K (kHz)1.146(11)1.109(12)  E (MHz) N lines 180 rms (MHz) Energy (cm -1 )245.9 C1 Second New Conformer at 246 cm-1 with OH Tunneling

Measured and calculated dipole moments for glycerol conformers G'Gg'gg' (1) MeasuredMP2Diff. % μaμa 0.780(6) D-0.81 D3.8 μbμb 0.30(2) D 0.30 D0.0 μcμc 1.134(4) D 1.25 D10.2 GGtgg' (2) MeasuredMP2Diff. % μaμa 1.749(3) D-1.86 D6.3 μbμb 0.901(2) D-1.04 D15.5 μcμc 0.161(2) D-0.13 D18.7 GGgg'g' (3) Measured a MP2Diff. % μaμa ≈1.7 D-1.61 D5.3 μbμb ≈0.2 D-0.20 D0.0 μcμc ≈1.7 D 2.22 D30.3 a Estimated from intensity comparisons GGtg'g (5) MeasuredMP2Diff. % μaμa 2.77(5) D-3.02 D6.9 μbμb 1.47(7) D-1.20 D18.4 μcμc ≈0. D 1.03 D---

Summary FTMW spectrum yielded 4-5 conformers Ab initio calculations aided new conformer identification Dipole moments determined & aided assignments GBT data covered good candidate lines for conformers 1 & 2, but no signals observed down to 5 – 10 mK noise level