1. Rotational spectroscopy of ethylamine into the THz Zbigniew Kisiel, Adam Kraśnicki Institute of Physics, Polish Academy of Sciences Ivan R. Medvedev, Christopher Neese, Sarah Fortman, Manfred Winnewisser, Frank C. De Lucia Department of Physics, The Ohio State University Holger S. P. Müller I. Physikalisches Institute, Universitat zu Köln 64th OSU International Symposium on Molecular Spectroscopy TC09

2. Ethylamine:  a = 1.057(6) D  b = 0.764(9) D  c = 0 D  a = 0.11(1) D  b = 0.65(1) D  c = 1.014(15) D AntiGauche  E (Gauche-Anti) = 50 – 100 cm  1 anti, cmw:Fischer + Botskor, J.Mol. Spectrosc. 91, 116 (1982) gauche, cmw:Fischer + Botskor, J.Mol. Struct. 97, 93 (1983) Fischer + Botskor, J.Mol. Spectrosc. 104, 226 (1984) anti, 10-270 GHz:Apponi et al., Astrophys. J. 673, 1240 (2008)

3. gauche-Ethylamine: Fischer and Botskor, J.Mol.Struct. 97, 93 (1983) Fischer and Botskor, J.Mol.Spectrosc. 104, 226 (1984) + torsion o = antisymm. e = symm.  E tors  1170.6(2) MHz  E inv  1391.4(2) MHz rotation + inversion a = antisymm. s = symm. (+ CH 3 torsion ? )

4. Rotational transitions in gauche-Ethylamine: Fischer and Botskor, J.Mol.Struct. 97, 93 (1983) Fischer and Botskor, J.Mol.Spectrosc. 104, 226 (1984)  E a  220.8(2) MHz  E s  2562.0(2) MHz   b within each of the four substates   c between substates with different torsional parity but in the same inversion state11 3 3

5. FASSST = FA st S canning S ubmillimeter S pectroscopic T echnique Tripled: 780 - 1125 GHz one source, two triplers3x Standard: 110 - 370 GHz three sources

6. 260 GHz 375GHz

7. Coverage of the ethylamine spectrum: FASST: 115 - 376 48 x 12 GHz synthesizer: 552 – 658 GHz 3 x FASST: 868 - 1081

8. Comparison with predictions: a-type: mainly anti b- and c-type: mainly gauche 298 K

9. Intensity correction at 1 THz using SO 2 lines: 9001000GHz Derived signal level Noise patch Raw Corrected

10. Intensity correction at 560 GHz using power signal: Apparent line intensity is divided by the power signal and the result is compared with CDMS and JPL database linelists.

11. Intensity correction at 560 GHz using power signal: A A – line in main Q-type sequence that becomes too attenuated by correction (kink in power) B B – R-type interloper that seems poorly predicted (but the one to high frequency from it is fine)

12. AABS AABS has been applied to many different types of broadband spectra: FASSST, cascaded multiplication THz, chirped pulse FTMW, Bruker FTIR..

13. Understanding of the spectrum (600 GHz): Anti, b R Gauche, c R, ae  ao Gauche: K a =13  12 c Q-branch, ao  ae transitions

14. Understanding of the spectrum (1 THz): Gauche, c R, ao  ae Gauche, c R, ae  ao SO 2 Anti, b R

15. The major spectroscopic constants for ethylamine: _____________________________________________________________________________________________ ANTI GAUCHE GAUCHE AE AO SE SO _____________________________________________________________________________________________ A /MHz 31758.1834(98) 32398.43(41) 32404.03(40) 32416.13(10) 32386.49(10) B /MHz 8749.2537(20) 8937.43(14) 8938.51(14) 8934.34(18) 8933.15(18) C /MHz 7798.9522(22) 7829.30(14) 7829.24(14) 7833.47(18) 7833.49(18) DJ /kHz 7.6378(10) 7.9369(21) 7.9988(22) 7.9888(45) 7.9819(50) DJK /kHz -27.088(23) -33.05(18) -27.69(15) -26.77(23) -32.86(24) DK /kHz 191.158(56) 219.5(29) 186.5(29) 198.4(40) 200.1(43) delJ /kHz 1.4156(12) 1.6575(60) 1.6804(58) 1.7088(19) 1.7137(21) delK /kHz -1.761(55) -44.2(16) -32.5(17) 14.82(35) 11.84(38) DE /MHz 220.67(22) 2561.67(17) Ga /MHz 181.66(25) 62.0(22) Fbc /MHz 64.4(12) 93.9(11) Gb /MHz 15.6(43) 25.3(31) Nlines 866 1586 366 sigma /MHz 1.5 1.8 0.8 max K_a 16 14 4 max f /GHz 1059 1057 651 _____________________________________________________________________________________________ unscaled B3LYP/6-31G(d,p) 7.568 7.756 -29.79 -31.28 196.1 205.3 1.382 1.592 2.686 10.92

16. Anti-ethylamine: problems with higher-J transitions J = 37  36, a R K a = 3 12 14 16 18 22

17. Anti-ethylamine: unresolved problems even at low-J and K a : Apponi et al., Astrophys. J. 673, 1240 (2008)

18.  Room temperature rotational spectrum of ethylamine was recorded up to 1081 GHz in three broadband segments.  Rotational transitions in the anti conformer and in the gauche ae and ao substates have been assigned and fitted for frequencies of well over 1 THz. For the gauche se and so substates the assignment reached 650 GHz.  The strongest features in the 600GHz and 1 THz regions are accounted for.  This is very much a work in progress: gauche: many transitions have been confidently assigned by using the Fischer+Botskor model of two coupled pairs of states but not yet well fitted anti: many unresolved problems at high K a and even low-J, low-K a  The next step will be to set up the full quartet of interacting inversion+torsion substates for the gauche rotamer.SUMMARY: