Presentation is loading. Please wait.

Presentation is loading. Please wait.

+ TERAHERTZ SPECROSCOPY OF METHYLAMINE R. A. Motiyenko, L. Margulès Laboratoire PhLAM, Université Lille 1, France V.V. Ilyushin, E.A. Alekseev Insitute.

Similar presentations


Presentation on theme: "+ TERAHERTZ SPECROSCOPY OF METHYLAMINE R. A. Motiyenko, L. Margulès Laboratoire PhLAM, Université Lille 1, France V.V. Ilyushin, E.A. Alekseev Insitute."— Presentation transcript:

1 + TERAHERTZ SPECROSCOPY OF METHYLAMINE R. A. Motiyenko, L. Margulès Laboratoire PhLAM, Université Lille 1, France V.V. Ilyushin, E.A. Alekseev Insitute of Radio Astronomy, NASU, Kharkov, Ukraine B. Drouin, S.Yu Jet Propulsion Laboratory J. Cernicharo, B. Tercero Centro de Astrobiologia (CSIC-INTA), Madrid Spain

2 + Interstellar methylamine  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  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 Intense spectrum extending far beyond 1 THz Good candidate for Herschel and SOFIA observations T = 293 K T = 150 K T = 50 K

3 + Rotational spectroscopy Two large amplitude motions: CH3 torsion NH2 inversion (wagging) 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 Motiyenko, Margulès and Ilyushin, 66th OSU Symposium, FA08, Columbus 2011 – 13CH3NH2 spectra up to 1 THz,

4 + 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 more than 10 transitions for each J and K a 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

5 + Lille sub-mm wave spectrometer Active sextupler 75 – 105 GHz//+15 dBm Absorbing cell SR7270 DSP Lock- in amplifier InSb Bolometer Amplifier Synthesizer Agilent E8257D 12.5-17 GHz Ethernet hub x6 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)

6 The JPL experimental setup PC FM Rf Synthesizer Multiplier chain Si detector Lock-in Sample cell Pump Reference 30 mTorr CH 3 NH 2 ×6×6 ×2×2 ×3×3 Frequency Multiplier Submillimeter Spectrometer (FMSS) …

7 6/23/2011Low Temperature Lineshape of HD 7 90.7 GHz → 101.8 GHz New THz Source for Spectroscopy Power Spectrum Under purged conditions

8 + The spectra 13 CH 3 NH 2 12 CH 3 NH 2 Lille : 500 – 630 GHz Lille : 775 – 945 GHz JPL : 1061 – 1093 GHz JPL : 1575 – 1625 GHz JPL : 2550 – 2660 GHz A = 103158 MHz A = 103155 MHz b Q 1 K = 6 - 5

9 + transition FIR freq. cm-1 FIR freq. MHz THz freq. MHz Diff. 1612E1+11511E1+185.5543 2564853.3892564837.47115.918 1612B1511B85.5664 2565216.1382565224.402-8.264 1612E1-11511E1-185.6079 2566460.2772566483.788-23.511 2011B1910B86.1932 2584007.1292584015.322-8.193 13 A12 A86.2135 2584615.7082584625.757-10.049 2410E1-1239E1-186.2555 2585874.8362585879.404-4.568 2011A1910A86.3767 2589508.3212589511.399-3.078 13 E1+112 E1+186.4152 2590662.5222590659.3513.171 13 B12 B86.4533 2591804.7312591807.648-2.917 13 E2-112 E2-186.6238 2596916.1922596912.6003.592 2410E1+1239E1+186.6711 2598334.2112598341.803-7.592 13 E1-112 E1-186.6980 2599140.6522599147.008-6.356 2410B239B86.8160 2602678.2032602696.431-18.228 1712E1+11611E1+187.0222 2608859.9242608861.053-1.129 1712B1611B87.0358 2609267.6422609266.2311.411 1712E1-11611E1-187.0772 2610508.7822610524.002-15.220 2111B2010B87.6596 2627968.6952627976.175-7.480 1413A 12A87.6849 2628727.1702628719.2727.898 2510E1-1249E1-187.7190 2629749.4622629735.30314.159 2111A2010A87.8431 2633469.8872633461.0758.812 1413B 12B87.9241 2635898.2062635885.06413.142 2510A249A87.9557 2636845.5502636835.7889.762 1812E1+11711E1+188.4901 2564853.3892564837.4717.143 1812B1711B88.5037 2565216.1382565224.402-8.334 1812E1-11711E1-188.5454 2566460.2772566483.788-25.924 2211E2-12110E2-188.7793 2584007.1292584015.3226.948 FIR vs THz measurements Ohashi et al. J. Mol. Spec. 126 (1987) 443 – 459

10 + The Hamiltonian K, K’ K K’ 0 1 J 0 1 J off diagonal contributions for K=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)

11 + Nuclear quadrupole hyperfine structure Hyperfine splittings Fit f hf Rotational frequencies f rot Global fit (Dr. Ohashi code) Expectation values Hyperfine constants Torsional- Wagging- Rotational parameters Two-step fitting scheme: 1.Hyperfine splittings to get pure rotational transitions 2.Rotational transitions to get torsional-wagging-rotational parameters 1406 hyperfine components were used to determine 587 rotational frequencies and 2 hyperfine constants rms = 0.014 MHz, wrms = 0.45

12 + The results 12 C spectra recorded and analyzed up to 2.6 THz 12 C Dataset consisting of 3868 lines 2540 microwave-terahertz lines 1328 FIR lines 80 parameters fitted RMS = 0.152 MHz, WRMS = 1.05 Major problems come from K>13 lines: new K-dependent terms should be included into the model 13 C species has not been detected in Orion survey of J. Cernicharo (upper limits for column densities will be provided in the paper to be publsihed) 13 CH 3 NH 2 12 CH 3 NH 2 A (MHz)103158.33874(61)103155.76112(95) B (MHz)22081.02148(13)22608.30528(12) C (MHz)21242.88318(13)21730.43756(12) wagging h 2v (MHz)-1546.2308(11)-1549.18582(89) h 4v (MHz)2.7313(10)2.7422(12) q2q2 21.53422(40)21.54636(49) f2f2 -0.0919627(66)-0.095832(20) torsion h 3v (MHz)-2488.8795(15)2493.5133(14) h 5v (MHz)2.86894(68)2.89100(72) f3f3 -0.165563(14)0.173766(16)

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


Download ppt "+ TERAHERTZ SPECROSCOPY OF METHYLAMINE R. A. Motiyenko, L. Margulès Laboratoire PhLAM, Université Lille 1, France V.V. Ilyushin, E.A. Alekseev Insitute."

Similar presentations


Ads by Google