1. THE BENDING VIBRATIONS OF THE C3-ISOTOPOLOGUES IN THE 1
THE BENDING VIBRATIONS OF THE C3-ISOTOPOLOGUES IN THE 1.9 TERAHERTZ REGION
Guido W. Fuchs University Kassel, Germany
P1901, ISMS Meeting, Urbana Champaign min, Tuesday,
01:47 PM - 02:02 PM Medical Sciences Building 274

2. Previous work: 𝐶 3 @ optical & IR
Optical 405nm
ν 1 symmetric stretching @ 𝑐𝑚 −1 (not IR-active)
Huggins 1882
Herzberg 1942
Douglas 1951
Gausset 1965
Maier 2001
Haddad 2014
Rohlfing 1989
ν 3 anti-symmetric stretching @ 𝑐𝑚 −1 (IR-active)
ν 2 bending @ 63 𝑐𝑚 −1 =1.9 𝑇𝐻𝑧 (IR-active)
Matsumura 1988
Moazzen-Ahmadi 1993
Krieg 2013
Hinkle
1988
Schmuttenmaer 1990
Gendriesch 2003
Giesen 2001
Mookerjea 2010, 2012, 2014

3. Excitation and Abundance of C3 in star forming cores around 1.8 THz
Herschel/HIFI observations towards W31C and W49N
B. Mookerjea, T. Giesen, J. Stutzki, et al. A&A 2010

4. Two previously unsolved aspects:
Mookerjea et al. noticed frequency shift of 12C12C12C astrophysical lines relative to laboratory data; e.g. P(6) has already 6 MHz offset (i.e. > linewidth) Possible reasons:
Dynamics in source (Doppler shift), e.g. outflows
imprecise laboratory data
Galactic [ 12 𝐶]/[ 13 𝐶]=20 − C3 13C-isotopologues are most likely detectable, but frequencies yet unknown. First astrophysical observation failed due to misassignment of isotopologue ⟹ Need of laboratory data
12C12C12C, 13C12C12C, C13C12C, C13C12C, C12C13C, C13C13C

5. Experimental setup in Kassel
See talk on Thursday RH01 at
Medical Sciences Building 274
01:30 PM
P1899: THE KASSEL LABORATORY ASTROPHYSICS THZ SPECTROMETRS
(talk has been moved from Friday to Thursday !!!)
THz spectrometer & laser ablation supersonic jet

6. Measurements of the main isotopologue 12C12C12C low bending vibration ν 2
Already data available [1] ⇒ B” and B’ from combination differences
Until now: Critical entries in molecular database (CDMS) not precise enough to analyse astrophysical observations[2]. ⇒ New measurements necessary
[1] Schmuttenmaer et al. 1990, Gendriesch et al [2] B. Mookerjea (private comm.)

7. The problem… P(2) and R(0) determine the precision of B“
Gendriesch et al. (Köln)
200 kHz
precision
Schmuttenmaer et al. (Berkeley) ~ 7 MHz precision
Now: Kassel 50 kHz precision
⇒ Δ ν 𝐵−𝐾 𝑃(2)≈2 𝑀𝐻𝑧
⇒ Δ 𝐵 𝐵−𝐾 ≈0.5 𝑀𝐻𝑧
6B“

8. Comparison of reduced exp. and calc
Comparison of reduced exp. and calc. molecular parameterset (in MHz) of 12C12C12C
isotopologue
parameter
This work
Previous exp. work [1]
Theor. Calc. [2]
12C12C12C 𝐵
(22)
(57) ν
(27)
(231) 𝐵
(19)
(48) 𝑞
(14)
(36)
-170.8
[1] J. Krieg et al. 2013, including data from Schmuttenmaer et al. 1990, Gendriesch et al. 2003
[2] B. Schröder et al. J.Chem.Phys. 144, (2016)
⇒ Δ 𝐵" 𝐵−𝐾 ≈0.55 𝑀𝐻𝑧
For higher J transitions deviation between predicted line positions from previous and new experimental data significant (> line width for J=6, e.g. P(6))

9. Bending mode transitions of 13C-isotopologues of CCC

10. Bending mode transitions of 13C-isotopologues of CCC

12. with 1:3 spin statistic Sample: 13 𝐶 12 𝐶 = 2 1

14. Spin statistics and line intensities of C C C isotopologues
Bose-Einstein statistic of two identical carbon nuclei ( 𝐼 12 =0)
Fermionic behaviour of outer C atoms ⇒ 3:1 statistical weights ( 𝐼 13 = 1 2 )

15. Similarity let to misassignment ⇒ failed astrophysical observation
R(J“) 13 12
Rot. Parameter B´= cm-1 13 12
Spin stat. Weights: ge/go = 1:1
Similarity let to misassignment ⇒ failed astrophysical observation
R(J“) 12
Rot. Parameter B”= cm-1 13 12
Spin stat. Weights: ge/go = 1:0
R(J“) 13
Rot. Parameter B”= cm-1 13 12
Spin stat. Weights: ge/go = 1:3

16. Fortrat diagram
13C in center
12C in center

17. Results
Line predictions for astrophysical observations

18. SOFIA far –IR observatory

19. Summary Measurement on C3 isotopologues and 12C12C12C were performed
Molecular parameters of 12C12C12C could be improved ⇒ better match with astrophysical observations
Molecular parameters of 13C isotopologues of C3 could be deterimend ⇒ explanation of failed astrophysical search ⇒ new searches under way

20. Thank you for your attention!
Acknowledgment
THOMAS F. GIESEN, A. BREIER, THOMAS BÜCHLING, VOLKER LUTTER, RICO SCHNIERER, K.M.T. YAMADA DFG GI 319/3-1, DFG GI 319/3-2, DFG SFB 956, Uni Kassel

21. Kassel Laboratory Astrophysics Group
Alexander Breier
Thomas Büchling
Johanna Chantzos
Eileen Döring
Doris Herberth
Steven Ingunza
Mona Kempkes
Pia Kutzer
Pascal Stahl
Björn Waßmuth
Daniel Witsch
Guido W. Fuchs
Thomas
F. Giesen

22. Authors: A. BREIER1) , THOMAS BÜCHLING1) , VOLKER LUTTER1) , RICO SCHNIERER2) , GUIDO W. FUCHS1) , THOMAS F. GIESEN1) ,
1) Institute of Physics, University Kassel, Kassel, Germany. 2) Institute of Physics, University of Rostock, Rostock, Germany;
Abstract: Short carbon chains are fundamental for the chemistry of stellar and interstellar ambiences. The linear carbon chain molecule C3 has been found in various interstellar and circumstellar environments, encompassing diffuse interstellar clouds, star forming regions, shells of late type stars, as well as cometary tails. Due to the lack of a permanent dipole moment C3 can only be detected by electronic transitions in the visible spectral range or by vibrational bands in the mid and far-infrared region. We performed experiments where C3 was produced via laser-ablation of a graphite rod with a 3 bar He purge and a subsequent adiabatic expansion into a vaccuum resulting in a supersonic jet. We report laboratory measurements of the lowest bending mode transitions of six 13C-isotopologues of the linear C3 molecule. Fifty-eight transitions have been measured between THz with an accuracy of better than 1 MHz. Molecular parameters have been derived to give accurate line frequency positions of all 13C isotopologues to ease their future interstellar detection. A dedicated observation for singly substituted 13CCC is projected within the SOFIA airborne observatory mission.

23. End

25. Virginia Diodes
Synthesiser (9-14 GHz) x 144

26. Liquid He InSb hot-electron bolometer (QMC instruments)

27. Laser ablation production of pure carbon molecules in a supersonic jet
photo
General
Valve
@ 20 Hz He
5 bar
Plasma
Rotating
graphite rod
reaction channel 4 mm
Nd:Yag
0.01 mbar

28. Energy expression linear molecule:
Ground state: 𝐸 0 𝐽 ℎ =𝐵" 𝐽 (𝐽+1) −𝐷" 𝐽 𝐽 𝐻" 𝐽 (𝐽+1) 3
=𝐵" 𝑓 −𝐷" 𝑓 2 +𝐻" 𝑓 with 𝑓=𝐽(𝐽+1)
Vibrational state: 𝐸 ± 𝐽 ℎ = ν+ 𝐵 ′ 𝑓 𝑙 − 𝐷 ′ 𝑓 𝑙 2 +𝐻′ 𝑓 𝑙 3
± 𝑞 ′ 𝑓 − 𝑞 𝐽 ′ 𝑓 2 + 𝑞 𝐽𝐽 ′ 𝑓 3
with 𝑓 𝑙 =𝐽 𝐽+1 − 𝑙 2
𝑞=𝑙−𝑡𝑦𝑝𝑒 doubling constant