1. 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

2. Motivation

3. Ilyushin & Hougen, J. Mol. Spectrosc., vol. 289, pp. 41-49, (2013)
PAM_C2v_2tops computer program
Ilyushin & Hougen, J. Mol. Spectrosc., vol. 289, pp , (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)pAr2pBr 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 torsional basis functions, second stage lowest torsional basis functions).

4. 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) ( = 0, J  60, K  30)
P. Groner, E. Herbst, F. C. De Lucia, B. J. Drouin, H. Mäder, J. Mol. Struct. 795 (2006) (12 = 1, J  38, K  16)
P. Groner, I. R. Medvedev, F. C. De Lucia, B. J. Drouin, J. Mol Spectrosc. 251 (2008) (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 Vol. 21, № 1.- P ( = 0, J  60, K  35; 12 = 1, J  52, K  32; 17 = 1, J  43, K  29)

5. 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 MHz
Synthesizer 360 MHz
Frequency divider f/2
Frequency Doubler (optional)
Detector Schottky
Reference synthesizer MHz

6. 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 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

7. SOLEIL synchrotron

8. Fragment of submillimeter wave spectrum of acetone
Prediction

9. 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

10. 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

11. 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

12. SUMMARY OF THE FIT
More than new lines were added to the dataset in the frequency range from 8 GHz to 930 GHz
The final dataset consists of microwave and 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)

13. High-J fits in molecules with large amplitude motions and K>2 Hamiltonian terms5 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.

14. High-J fits in molecules with large amplitude motions and K>2 Hamiltonian terms5 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 (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 (2014).
Toluene, m =0,1,2,+/ J up to 94
V. V. Ilyushin, E.A. Alekseev, Z.Kisiel, Lech Pszczółkowski, MS in preparation

15. Thank you for your attention