1. 1 The rotational spectrum of 13 CH 3 NH 2 up to 1 THz Roman A. Motiyenko, Laurent Margulès PhLAM, Université Lille 1 Vadim Ilyushin Institute of Radio Astronomy of NASU, Kharkov

2. Interstellar methylamine 12 CH 3 NH 2 detected in Sgr B2 and Orion KL at 3 mm: Kaifu et al. ApJ 191 (1974) L135 in cm wave range: Fourikis et al. ApJ 191 (1974) L139 Detected in the atmosphere of Jupiter Kuhn et al. Geophys. Res. Lett. 4 (1977) 203 Precursor of glycine NH 2 CH 2 COOH CH 3 NH 2 +CO 2 mixture irradiated by UV: Bossa et al. A&A 506 (2009) 601; Lee et al. ApJ 697 (2009) 428; Holtom et al. ApJ 626 (2005) 940

3. Methylamine in THz domain Intense spectrum extending far beyond 1 THz Good candidate for Herschel observations (HIFI instrument 480 – 1910 GHz) T = 293 K T = 150 K T = 50 K detected in interstellar medium here

4. Previous studies 12 CH 3 NH 2 : more than 10 publications since 1947 Ohashi and Hougen, J. Mol. Spec. 121 474-501 (1987) – effective rotational-tunneling Hamiltonian Ilyushin et al., J. Mol. Spec. 229 170-187 (2005) – extension of the model, fit within experimental accuracy of microwave and IR data Ilyushin and Lovas, J. Phys. Chem. Ref. Data 36 (2007) – accurate predictions and intensity calculation up to 500 GHz for all transitions with J<30 Yu and Drouin, Columbus 2009 WH11 – extension of the measurements up to 1.6 THz Several deuterated species also studied: CD 3 NH 2, CD 3 ND 2, CH 3 NHD 13 CH 3 NH 2 : no spectroscopic studies

5. Two large amplitude motions: CH 3 torsion and NH 2 inversion -Ambiguity in barrier heights Torsional barrier: 684.1 cm -1 Takagi, J. Phys. Soc. Jpn 30, 1145, 1971:684.1 cm -1 718.4 cm -1 Kreglewski, J. Mol. Spec. 133, 10, 1989:718.4 cm -1 536.2 cm -1 Woon, Columbus 2007, RH08:536.2 cm -1 Barrier to inversion: 1688 cm -1 Tsuboi, J. Mol. Spec. 22, 272, 1967:1688 cm -1 2081 cm -1 Sztraka, Acta Chim Hung 124, 865, 1987:2081 cm -1 1943 cm -1 Kreglewski, J. Mol. Spec. 133, 10, 1989:1943 cm -1 1366 cm -1 Woon, Columbus 2007, RH08:1366 cm -1

6. 6 Tunneling splittings A 1, A 2, B 1, B 2, E 1, E 2 Each energy level is labeled by the values of usual quantum numbers J and K=K a and by an overall torsion- wagging-rotation symmetry species of G 12 PI group: A 1, A 2, B 1, B 2, E 1, E 2 E E 1+1 E 1-1 E 2+1 E 2-1 Additional labeling occurs for E symmetry species in order to distinguish between positive and negative K in a symmetric rotor basis set: E 1+1, E 1-1 and E 2+1, E 2-1 E2E2 E1E1 E 2+1 E 2-1 E 1+1 E 1-1 A2A2 A1A1 B2B2 B1B1 J, K a Selection rules: A 1 ↔ A 2 ; B 1 ↔ B 2 ; E 1 ↔ E 1 ; E 2 ↔ E 2 up to 10 transitions for each J and K a 13CH3NH2: 11 1 B1 10 2 B2 195100.935 MHz 11 1 E2-1 10 2 E2-1 200937.737 MHz 11 1 A1 10 2 A2 200963.096 MHz 11 1 E1-1 10 2 E1+1 201587.095 MHz 11 1 E2-1 10 2 E2+1 204600.355 MHz 11 1 B2 10 2 B1 247370.367 MHz 11 1 A2 10 2 A1 253172.102 MHz 11 1 E1+1 10 2 E1+1 256996.802 MHz 11 1 E2+1 10 2 E2-1 257421.111 MHz 11 1 E2+1 10 2 E2+1 261083.734 MHz

7. Lille sub-mm wave spectrometer Absorbing cell SR7270 DSP Lock-in amplifier InSb Bolometer Amplifier Synthesizer Agilent E8257D 12.5-17 GHz Active sextupler 75 – 105 GHz//+15 dBm Ethernet hub x6 x2: 150 – 215 GHz x3: 225 – 315 GHz x5: 400 – 530 GHz x6: 500 – 630 GHz x9: 750 – 945 GHz x2: 150 – 215 GHz x3: 225 – 315 GHz x5: 400 – 530 GHz x6: 500 – 630 GHz x9: 750 – 945 GHz xNxN N = 2, 3, 5, 6(2x3), 9(3x3)

8. 13 CH 3 NH 2 spectrum 775 – 945 GHz E 2-1 E 2+1 E 1+1 E 1-1 B 1, B 2 A 1, A 2 ΔJ=0, K=6←5

9. 14 N nuclear quadrupole hyperfine structure Hyperfine splittings Fit f hf Rotational frequencies f rot Global fit Expectation values Hyperfine constants Torsional- Wagging- Rotational parameters Two-step fitting scheme: pure rotational transitions 1.Hyperfine splittings to get pure rotational transitions torsional- wagging-rotational parameters 2.Rotational transitions to get torsional- wagging-rotational parameters

10. Hyperfine structure: results 1878 hyperfine components were used to determine 970 rotational frequencies and 2 hyperfine constants rms = 0.014 MHz wrms = 0.5 13 CH 3 NH 2 12 CH 3 NH 2 χ + (MHz)-2.4097(32)-2.4136(12) χ – (MHz)6.0661(36)6.0646(24)

11. The Hamiltonian K, K’ K K’ 0 1 J 0 1 J off diagonal contributions for lKl=1 The Hamiltonian matrix n =1: nontunneling motion n = 2, 4, 6…: tunneling involving wagging n = 3, 5, 7…: tunneling involving torsion Ohashi and Hougen, J. Mol. Spec. 121 474-501 (1987) Ohashi et al., J. Mol. Spec. 126 443-459 (1988)

12. 13 CH 3 NH 2 results as of 10/06/11 2525 rotational transitions in the range 150 – 950 GHz J max = 43, K a,max = 13 70 fitted parameters rms = 0.052 MHz wrms = 0.88 13 CH 3 NH 2 12 CH 3 NH 2 A (MHz)103158.33874(61)103155.7604(11) B (MHz)22081.02148(13)22608.30543(32) C (MHz)21242.88318(13)21730.43741(32) wagging h 2v (MHz)-1546.2308(11)-1549.18612(77) h 4v (MHz)2.7313(10)2.73198(95) q2q2 21.53422(40)21.54929(52) f2f2 -0.0919627(66)-0.096750(38) torsion h 3v (MHz)-2488.8795(15)-2493.5140(12) h 5v (MHz)2.86894(68)2.88400(55) f3f3 -0.165563(14)-0.173417(25) Dr. Ohashi’s code improved and extended to treat transitions with J>30

13. 13 Acknowledgements Dr. N. Ohashi for providing his code for methylamine Programme National de Physico-Chimie du Milieu Interstellaire - CNRS ANR-08-BLAN-0054 Dr. N. Ohashi for providing his code for methylamine Programme National de Physico-Chimie du Milieu Interstellaire - CNRS ANR-08-BLAN-0054