Fourier-Transform absorption spectroscopy of C3 in the 3 antisymmetric stretch mode region M. VERVLOET, M. A. MARTIN-DRUMEL., D. W. TOKARYK, O. PIRALI ISMO, CNRS-Universite Paris-Saclay, Orsay, France AILES beamline, Synchrotron SOLEIL, Saint-Aubin, France Department of Physics, University of New Brunswick, Fredericton, NB, Canada

Objective: record the (0,n2l,1) - (0,n2l,0) transitions Context C3 is a linear, symmetric molecule 4050 Å band from comet spectra first seen in 1882; assigned to C3 by Douglas (1951) Gausset et al. (1965) studied the A 1Пu – X 1Σg+ electronic system – the analysis revealed a large Renner Teller splitting in the A 1Пu state and low energy (about 65 cm-1) of the X 1Σg+ 2 bending state 3 vib modes (1, 2l, 3), 2 and 3 and IR active: diode laser spectroscopy of the 3 band by Kawaguchi et al, J. Chem. Phys, 91 (1989) and 2 band by Schmuttenmaer et al. 1990 Lines of the 3 band of C3 detected in the circumstellar envelopes (Hinkle et al., Science 1988) and absorption lines of 2 band (Giesen et al., ApJ 2001) Objective: record the (0,n2l,1) - (0,n2l,0) transitions

Experimental set-up on the AILES beamline of SOLEIL Electrical DC discharge coupled to the FT 24 m absorption pathlength Resolution = 100MHz (0.004 cm-1) Discharge : ~ 1KV / 1A Gas mixture : CH4 seeded in 1 mbar He Intense lines are due to CO

Comparison with diode laser spectrum: (0,n2l,1) - (0,n2l,0) (0,2,0) P(40) (0,2,0) R(13) R(14) (0,1,0) P(7) (0,1,0)  P(6) Kawaguchi et al. (1989) (0,0,0) P(40) Wavenumbers (cm-1)

Stimulated Emission Pumping Data from electronic transitions to support our analysis In addition to IR data (Kawaguchi et al., Krieg et al.) and ab-initio calculations (Per Jensen) Analysis of the 4050 Ǻ group : A 1Пu – X 1Σg+, L. Gausset et al. Astrophys. J. 142, 45 (1965) (000) , (010), (020), (020), (030) , (040)  Stimulated Emission Pumping - Nothrup and Sears (0,2n 2,0) states with l= 0 (), 2 () Rohlfing and Goldsmith (0, 2n+1 2, 1) states with l=1 ()

Spectral analysis procedure and effective Hamiltonian J-1 R(J-1) J J+1 P(J+1) F2(J) for the lower state = R(J-1)-P(J+1) R(J) P(J) F2(J) for the lower state = R(J)-P(J) (0, 2,1) (0, 2,1) USCD (0, 2,0) LSCD (0, 2,0) Formulation from Maki et al, J. Mol. Spec. 36, 433-447 (1970) includes the l-type resonance < J,v,l|H|J,v,l > = Bv[J(J+1) - l2] -Dv [J(J+1) - l2]2 + Hv[J(J+1) - l2]3 < J,v,l|H|J,v,l ± 2> = (1/4)q[(v l)(v ± l + 2]½ {[J(J+1)-l(l ±1)] [J(J+1) – (l ± 1)(l ± 2}½ q → q +qjJ(J+1) + qjjJ2(J+1)2 ±

Analysis (021)-(020); (021) - (020) Extension of Kawaguchi et al observations up to J=55 Plots of the 2(J) for (0,2,1)  states shows a local perturbation for J=33-34. Proposition of (190)  state as the perturber level. Based on SEP data from Northrup and Sears who observed (180)  at 1993 cm-1 2(J) J(J+1)

Analysis of (041) - (040) ; (041) - (040); (041) - (040) Gausset et al. provide term values for (040) state. Northrup and Sears provide low J combination differences for the (040) state Lines involving (040) are more intense than the l=0 and 2 and the l-doubling effect is weaker Analysis of (041) - (040)  band rely on the model and fit. 41 lines f levels, Jmax=45 Ev B/cm-1 D/10-5 cm-1 H/10-9 cm-1 q/10-2 cm-1 qJ/10-6 cm-1 (0,4,0) Σ 286.52 0.468074(30) 0.2744(38) 0.133(14) 0.4885(8) -0.3685(31) (0,4,0) Δ 287.250(10) 0.468929(26) 0.2929(27) 0.181(9) (0,4,0) Γ 289.302(11) 0.471883(23) 0.3369(25) 0.200(8) Ev B/cm-1 D/10-5 cm-1 H/10-9 cm-1 q/10-2 cm-1 qJ/10-6 cm-1 (0,4,1) Σ 2260.3657(18) 0.472022(28) 0.3130(37) 0.109(14) 0.5706(8) -0.4848(30) (0,4,1) Δ 2257.3903(97) 0.474334(24) 0.3704(26) 0.214(9) (0,4,1) Γ 2249.312(11) 0.481029(23) 0.5116(25) 0.369(8) 200 lines (, ,  states); RMS of the fit about 0.003 cm-1 (exp accuracy about 0.0005 cm-1)

Summary (050) R(31) R(33) (050) R(34) (040) R(18) (040) R(21) R(23) (040)  (040) R(27) R(26) (030) R(8) R(9) (030) R(14) R(16) R(15) Extension of the analysis to bands involving higher quanta of 2 Comparison with recent theoretical calculations (Schröder and Sebald, J. Chem. Phys 2016) We plan to analyse our data using semi-rigid bender approach (S. Ross, UNB)

Atlas of Comet 122P/de Vico: Cochran and Cochran, Icarus 2002 C3 in cometary spectra: « 4050 Å group » : A1u – X1g+ (Gausset el al. 1965 and Merer 1967) Span from 3350 Å to 4700 Å

Atlas of Comet 122P/de Vico: Cochran and Cochran, Icarus 2002 000 -000 Пu – Σg+ 000 -020 Пu – Σg+ 000 -040 Пu – Σg+ 000 -040 Пu – Δg 020 -020 Пu- – Σg+ 020 -040 Пu- – Σg+ 020 -000 Пu+ – Σg 020 -020 Пu+ – Σg 020 -020 Пu+ – Δg 020 -040 Пu+ – Σg 020 -040 Пu+ – Δg 040 -000 Пu- – Σg+ 040 -020 Пu- – Σ 100 -000 Пu – Σg+ 010 -010 Δg – Пu 010 -030 Δg – Пu 010 -010 Σg- – Пu 010 -030 Σg- – Пu 010 -010 Σg+ – Пu 010 -030 Σg+ – Пu 030 -030 Σg- – Пu

Atlas of Comet 122P/de Vico: Cochran and Cochran, Icarus 2002 Identification of 16 U lines all shifted by 0.3 cm-1 in comparison to lab data 8 for 010 -050 Σg- – Пu 8 for 010 -050 Σg+ – Пu Due to uncertainty of the energy of (051) that we use to determine (050) involved in the cometary band (about 0.5 cm-1) Gausset A (010) Rohlfing X (051) X (050) X (000) THANK YOU!