1. MICROWAVE AND FIR SPECTROSCOPY OF DIMETHYLSULFIDE IN THE GROUND, FIRST AND SECOND EXCITED TORSIONAL STATES
V. Ilyushin1, I. Armieieva1, O. Dorovskaya1, M. Pogrebnyak1, I. Krapivin1, E. Alekseev1 , R. Motiyenko2, L. Margulès2, F. Kwabia Tchana3, A. Jabri4, L. Manceron5, S. Bauerecker6, C. Maul6
1 Institute of Radio Astronomy of NASU, Kharkov, Ukraine
2 Laboratoire PhLAM, Université de Lille 1, France
3 LISA, Université Paris-Est Créteil, Université Paris Diderot, France
4Sorbonne Universités, MONARIS, Paris, France
5 Synchrotron SOLEIL, Ligne AILES, Gif-sur-Yvette, France
6 Institut für Physikalische und Theoretische Chemie, Technische Universität Braunschweig, Braunschweig, Germany

2. PAM_C2v_2tops computer program
Motivation
=0.062
PAM_C2v_2tops computer program
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}
=0.102

3. Motivation
AA species only

4. 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

5. 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

6. SOLEIL synchrotron

7. Fragment of submillimeter wave spectrum of dimethylsulfide
theory
experiment
theory
experiment

8. Overview of the 15 = 1  0 torsional band of DMS
theory
experiment
149.0
177.5
206.0
cm-1
163.25
191.75
220.25

9. Q-branch theory experiment 182.43 182.93 183.43 cm-1 182.68 183.18
183.68

10. Fragment of R-branch theory experiment 198.66 198.78 198.90 cm-1
198.72
198.84
198.96

11. Fragment of P-branch theory experiment 163.05 163.19 163.33 cm-1
163.12
163.26
163.40

12. Reassignment of the FIR spectra
AA transitions only
A. Jabri, V. Van, H. V. L. Nguyen, H. Mouhib, F. Kwabia Tchana, L. Manceron, W. Stahl, and I. Kleiner, A&A 589, A127 (2016)

13. Overview of the data set fit quality
# lines in the fit, wrms = 0.88, Jmax=60, Kamax=30
Npar = 89
Current work
A. Jabri et al., A&A 589, A127 (2016)
Unc. #
rms
5 kHz 98
4.7 kHz 99
5.5 kHz
10 kHz
3814
8.7 kHz
30 kHz
7871
24.1 kHz
40 kHz
300
27.3 kHz
305
52.7 kHz
50 kHz
7134
54.7 kHz 18
48.6/ 69.7 kHz
100 kHz
3547
68.0 kHz
180
84.6 kHz
200 kHz 29
90.0 kHz
cm-1
1013
cm-1
578
cm-1
gs transitions rms=48.79 kHz
11= transitions rms=41.30 kHz
15 = transitions rms=48.80 kHz
15   transitions rms=39.22 kHz

14. SUMMARY OF THE FIT
More than new lines were added to the dataset in the frequency range from 49 GHz to 660 GHz
The dataset consists of microwave and 1013 FIR lines covering (15, 11) = (0,0),(0,1),(1,0) torsional states.
The range of rotational quantum numbers is expanded up to J = 60 and Ka=30
Obtained theoretical model containing 89 parameters provides a fit within experimental error (weighted rms 0.88)

15. Comparison with ab initio calculations
Senent M. L., Puzzarini C., Dominguez-Gomez R., Carvajal M., Hochlaf M., 2014, J. Chem. Phys., 140,
CCSD(T)/AVTZ level
A. Jabri, V. Van, H. V. L. Nguyen, H. Mouhib, F. Kwabia Tchana, L. Manceron, W. Stahl, and I. Kleiner, A&A 589, A127 (2016)
15 = cm-1 CCSD/VTZ anharmonic 182 cm-1
11 = cm-1 CCSD/VTZ anharmonic 177 cm-1

16. Thank you for your attention
This work was done under support of the Volkswagen foundation. The assistance of Science and Technology Center in Ukraine is acknowledged (STCU partner project #P686).