THE TORSIONAL FUNDAMENTAL BAND AND ROTATIONAL SPECTRA UP TO 940 GHZ OF THE GROUND, FIRST AND SECOND EXCITED TORSIONAL STATES OF ACETONE V.V. Ilyushin1, I.A. Armieieva1, O.A. Dorovskaya1, E.A. Alekseev1, R.A. Motiyenko2, L. Margulès2, B. Drouin3, O. Pirali4, M. Tudorie5 1 Institute of Radio Astronomy of NASU, Kharkov, Ukraine 2 Laboratoire PhLAM, Université de Lille 1, France 3 JPL, California Institute of Technology, Pasadena, USA 4 Synchrotron SOLEIL, Ligne AILES, Gif-sur-Yvette, France 5 Service de Chime Quantique et Photophysique, Université Libre de Bruxelles, Belgium

Motivation

Ilyushin & Hougen, J. Mol. Spectrosc., vol. 289, pp. 41-49, (2013) PAM_C2v_2tops computer program Ilyushin & Hougen, J. Mol. Spectrosc., vol. 289, pp. 41-49, (2013) A general expression for the fitting Hamiltonian is written as H = (1/4) knpqr1r2s1s2t1t2 Bknpqr1r2s1s2t1t2  {J2kJznJxpJyq[pAr1pBr2cos(3s1A) cos(3s2B)sin(3t1A)sin(3t2B) + (-1)(n+q) pBr1pAr2cos(3s1B) cos(3s2A)sin(3t1B)sin(3t2A)]                                                                                              + [(-1)(n+q)sin(3t2A)sin(3t1B)cos(3s2A)cos(3s1B)pAr2pBr1 + sin(3t2B)sin(3t1A)cos(3s2B)cos(3s1A)pBr2pAr1]JyqJxpJznJ2k} The PAM_C2v_2tops program makes use of an explicit two-dimensional potential function and carries out a global fit of rotational transitions in several torsional states simultaneously. A two step diagonalization procedure is used (first stage - 441 torsional basis functions, second stage - 66 lowest torsional basis functions).

The acetone data set from the recent literature P. Groner, S. Albert, E. Herbst, F. C. De Lucia, F. J. Lovas, B. J. Drouin, J. C. Pearson, Ap. J. Supp. 142 (2002) 145-151. ( = 0, J  60, K  30) P. Groner, E. Herbst, F. C. De Lucia, B. J. Drouin, H. Mäder, J. Mol. Struct. 795 (2006) 173-178. (12 = 1, J  38, K  16) P. Groner, I. R. Medvedev, F. C. De Lucia, B. J. Drouin, J. Mol Spectrosc. 251 (2008) 180-184. (17 = 1, J  31, K  8) I.A. Armieieva, V.V. Ilyushin, Е.А. Alekseev, O.А. Dorovskaya, L. Margulès, R. A. Motiyenko, Radio physics and radio astronomy.- 2016.- Vol. 21, № 1.- P. 37-47. ( = 0, J  60, K  35; 12 = 1, J  52, K  32; 17 = 1, J  43, K  29)

MW spectrometer in Kharkiv BWO, 34 – 150 GHz PLL IF = 25 MHz FM modulated synthesizer 25 MHz Klystron 3.4 – 5.2 GHz IF = 5 MHz Absorbing cell Amplifier Lock-in detector Sine wave synthesizer 7 – 120 KHz DAC DDS AD9851 30 – 60 MHz Band-pass amplifier 390-430 MHz Synthesizer 360 MHz Frequency divider f/2 Frequency Doubler (optional) Detector Schottky Reference synthesizer 390-430 MHz

The Lille THz spectrometer Based on solid state sources Frequency multiplication technique Absorption cell – stainless steel tube 2.2 m Main detector InSb bolometer In the range 75 – 330 GHz solid state Schottky diode detectors Frequency multiplication chain in frequency range 150 – 990 GHz : Synthesizer Agilent E8257D 12.5-18.5 GHz Active multiplier (VDI) x6 75–110GHz Multipl. Passifs (VDI) x2: 150 – 220 GHz x3: 225 – 330 GHz x5: 400 – 500 GHz x6: 500 – 660 GHz x9: 750 – 990 GHz Variable attenuator THz spectrometer

SOLEIL synchrotron

Fragment of submillimeter wave spectrum of acetone Prediction

Overview of the band center 782626,749 m=1 3938,2 — 3837,2 782543,531 m=2 4134,7 — 4033,8 782479,236 m=0 4231,5 — 4130,12 782488,426 m=0 4231,11 — 4130,11 782616,226 m=1 5329,24 — 5230,23 782589,799 m=0 4231,12 — 4130,11 782596,497 m=0 4231,12 — 4130,12

Fragment of experimental record FIR lines 782626,749 m=1 3938,2 — 3837,2 782543,531 m=2 4134,7 — 4033,8 782479,236 m=0 4231,5 — 4130,12 782488,426 m=0 4231,11 — 4130,11 782616,226 m=1 5329,24 — 5230,23 782589,799 m=0 4231,12 — 4130,11 782596,497 m=0 4231,12 — 4130,12

Fragment of experimental record FIR lines 782626,749 m=1 3938,2 — 3837,2 782543,531 m=2 4134,7 — 4033,8 782479,236 m=0 4231,5 — 4130,12 782488,426 m=0 4231,11 — 4130,11 782616,226 m=1 5329,24 — 5230,23 782596,497 m=0 4231,12 — 4130,12

SUMMARY OF THE FIT More than 14 000 new lines were added to the dataset in the frequency range from 8 GHz to 930 GHz The final dataset consists of 26137 microwave and 1120 FIR lines The range of rotational quantum numbers is expanded up to J = 90 Obtained theoretical model containing 119 parameters provides the fit within experimental error (weighted rms 0.89)

High-J fits in molecules with large amplitude motions and K>2 Hamiltonian terms 5 10 15 20 25 30 35 J 60 180 120 240 300 Ered cm-1 vt=0 vt=1 vt=2 vt=3 vt=4 vt=5 Reduced energies Ered for torsion-rotation levels of acetone of species G in G36.

High-J fits in molecules with large amplitude motions and K>2 Hamiltonian terms 5 10 15 20 25 30 35 J 60 180 120 240 300 Ered cm-1 vt=0 vt=1 vt=2 vt=3 vt=4 vt=5 K=3 K=4 K=4 Acetic acid, vt=0,1, J up to 79 V. V. Ilyushin, C. P. Endres, F. Lewen, S. Schlemmer, B. J. Drouin „Submillimeter wave spectrum of acetic acid“Journal of Molecular Spectroscopy Vol. 290 pp. 31 - 41 (2013). Acetaldehyde vt=0,1,2 J up to 66 I.A. Smirnov, E.A. Alekseev, V.V. Ilyushin, L. Margulés, R.A. Motiyenko, B.J. Drouin « Spectroscopy of the ground, first and second excited torsional states of acetaldehyde from 0.05 to 1.6 THz » Journal of Molecular Spectroscopy Vol. 295 pp. 44 - 50 (2014). Toluene, m =0,1,2,+/-3 J up to 94 V. V. Ilyushin, E.A. Alekseev, Z.Kisiel, Lech Pszczółkowski, MS in preparation

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