1. 60th OSU International Symposium on Molecular Spectroscopy TF03 The millimeter-wave rotational spectrum of lactic acid Zbigniew Kisiel, Ewa Białkowska-Jaworska, Lech Pszczółkowski Institute of Physics, Polish Academy of Sciences Warszawa, Poland

2. The lactic acid molecule Borba et. al., PCCP 6, 2101 (2004)  ZPE  Population kJ/mol% @ 298K SsC 0.091.7 GskC 8.0 3.6 G’sk’C 8.6 2.9 AaT10.0 1.6 SsC GskC 16.4 kJ/mol

3. Lowest energy vibrational states in lactic acid  30 = 60 cm -1  28 = 240  29 = 224  27 = 287 vibrational spectrum: Borba et. al., PCCP 6, 2101 (2004) rotational spectrum: van Eijck, JMS 101, 133 (1983) Studied in this work, and assigned with confidence Measured, but only tentative assignment

4. The Warsaw broadband millimeter-wave spectrometer

5. The IFPAN MMW spectrometer 120-350 GHz Istok BWO in electromagnet

6. Analysis carried out using the AABS software package All recorded spectra (typically 0.5 GHz each) combined into a single continuous spectrum Spectra and predictions displayed alongside with two previewing programs Graphical assignment and automated transfer of frequencies and quantum numbers to datafiles Fitting and predictions with ASFIT/ASROT (H.M.Pickett’s SPFIT/SPCAT can also be used) AABS = A ssignment and A nalysis of B roadband S pectra available on the PROSPE webpage: http://info.ifpan.edu.pl/~kisiel/prospe.htmhttp://info.ifpan.edu.pl/~kisiel/prospe.htm

8. Loomis-Wood type plot for K a = 1  0 transitions Ground state  30 = 1

9.  a /  b b: 32 8,24  31 9,23 a: 32 9,24  31 9,23 a: 32 8,24  31 8,23 b: 32 9,24  31 8,23  tot = 2.32 D  tot = 2.34 D  tot = 2.33 D

10. Spectroscopic constants determined for the ground state

11. Dataset for the ground state MMW: 171-318 GHz FTMW: 8-16 GHz CMW: 27-39 GHz

12. Quartic constants for the ground state GAMESSGAMESS FCONVFCONV VIBCAVIBCA } 1.2 %

13. The  30 satellite sequence ?? Sixth quantum ? 30 mode Observed for transitions with lowest values of K c, owing to the very small change in A on excitation of the 30 mode

14. Changes in constants on excitation of the 30 mode  quartics  octics sextics  A,B,C  KK JJ   C JJ

15. The 30 torsional mode Intramolecular hydrogen bond  30  60 cm - 1 GAMESSGAMESS output displayed with ChemCraftChemCraft

16. methyl torsion,  29 = 224 cm - 1 Assignment of the minor vibrational satellites

17. Lowest energy vibrational states in lactic acid  30 = 60 cm -1  28 = 240  29 = 224  27 = 287 v u ?

18. Conclusions:Conclusions: Spectroscopic constants determined for the ground state and nine different vibrational excited states Strongest features in rotational spectrum can be predicted with confidence well into the submillimeter-wave region Well-behaved rotational spectrum in lowest states: meaningful quartics in Watson’s Hamiltonian and all transitions fitted to within experimental accuracy Vibrational states crowded above 200 cm –1 and subject to various perturbations In progress: Dipole moment measurement Search for hydrogen-bonded complexes