1. Max Planck Institute for the Structure and Dynamics of Matter
Segmented Chirped-pulse Millimeter-wave Spectroscopy for Astrochemistry
Benjamin E. Arenas1 Amanda L. Steber1,2 Sébastien Gruet1,2 Melanie Schnell1,2
1Max Planck Institute for Structure and Dynamics of Matter, Hamburg, Germany
2The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Hamburg, Germany
Max Planck Institute for the Structure and Dynamics of Matter

2. Introduction To increase the output of laboratory spectra for:
Astrochemistry
Organic Molecules
Interstellar Ice Grains
Analysis of Chiral Compounds
Intermolecular Interactions
Controlling Cold Molecules
To increase the output of laboratory spectra for:
Detecting new molecules;
Exploring the importance of excited states and isotopologues;
Chemical reactions.
See also: Amanda L. Steber, “The Study of Acenaphthene and its Complexation with Water”, [TH12]
Segmented Chirped-pulse Millimeter-wave Spectroscopy for Astrochemistry

3. 75 –110 GHz Spectrometer
Segmented chirped-pulse Fourier transform millimeter-wave rotational spectrometer
Pulses
AWG writes pulses
Amplified and up-converted
Chamber
mmw transmitted into chamber
Interaction with molecules
Detection
FID collected, down-converted, amplified and digitised
Fourier transform
Local oscillator frequency for down-conversion of FID
1 J.L. Neill et al., Opt. Express 21 (2013)
Segmented Chirped-pulse Millimeter-wave Spectroscopy for Astrochemistry

4. 75 –110 GHz Spectrometer Still to come…
Molecular interaction chamber
Receiver
Sample
inlet
mmw
transmitter
Still to come…
New molecular interaction chamber
Electrical discharge
Laser ablation
Segmented Chirped-pulse Millimeter-wave Spectroscopy for Astrochemistry

5. 1,2-Propanediol 1,2-Ethanediol 1,2-Propanediol AKA ethylene glycol
Detected in the ISM in 20022
1,2-Propanediol
6.5 – 25.0 GHz3
7 conformers
38 – 70, 200 – 230, – 400 GHz4
3 conformers
2 J. M. Hollis et al., ApJ 571 (2002) L59-L62
3 F. J. Lovas et al., J. Mol. Spectrosc. 257 (2009) 82-93
4 J.-B. Bossa et al., A&A 570 (2014) A12
Segmented Chirped-pulse Millimeter-wave Spectroscopy for Astrochemistry

6. The Conformers of 1,2-Propanediol
3 F. J. Lovas et al., J. Mol. Spectrosc. 257 (2009) 82-93
Conformer
Energy (cm-1) 1 2 74 3
115 4
212 5
230 6
349 7
375
Segmented Chirped-pulse Millimeter-wave Spectroscopy for Astrochemistry

7. 1,2-Propanediol – Spectrum
Segmented Chirped-pulse Millimeter-wave Spectroscopy for Astrochemistry

8. 1,2-Propanediol – Spectrum
Segmented Chirped-pulse Millimeter-wave Spectroscopy for Astrochemistry

9. 1,2-Propanediol – Structures
Conformer 1
Conformer 2
Conformer 3
Conformer 4
Segmented Chirped-pulse Millimeter-wave Spectroscopy for Astrochemistry

10. 1,2-Propanediol Comparison
Conformer 1
Lovas et al., 2009
A (MHz)
(14)
(8)
B (MHz)
(54)
(5)
C (MHz)
(52)
(4)
ΔJ (kHz)
(94)
0.738(7)
ΔJK (kHz)
5.3417(33)
5.276(30)
ΔK (kHz)
2.481(18)
2.53(10)
δJ (kHz)
(31)
0.1631(16)
δK (kHz)
3.171(10)
3.180(31)
# of Lines
122 -
MW rms (kHz)
25.304
Segmented Chirped-pulse Millimeter-wave Spectroscopy for Astrochemistry

11. Vibrational States of 1,2-Propanediol
Segmented Chirped-pulse Millimeter-wave Spectroscopy for Astrochemistry

12. Isopropyl Cyanide Studied in the mw and mmw regions
28 – 38 GHz5
3 vibrationally excited states
0 – 20, 37 – 69, 303 – 346, 589 – 600 GHz6
Detected in the ISM in 20147
First branched organic molecule
Could point towards other branched organic molecules
Possible amino acid precursor
5 J. R. Durig and Y. S. Li, J. Mol. Spectrosc. 21 (1974)
6 H. S. P. Müller et al., J. Mol. Spectrosc. 267 (2011)
7 A. Belloche et al., Science 345 (2014)
Segmented Chirped-pulse Millimeter-wave Spectroscopy for Astrochemistry

13. Isopropyl Cyanide In collaboration with Dr. B. Michela Giuliano
at the Centre for Astrochemical Studies at MPE
Segmented Chirped-pulse Millimeter-wave Spectroscopy for Astrochemistry

14. Isopropyl Cyanide ν29 Ground state ν17
Müller et al., 2011
A (MHz)
(16)
(31)
B (MHz)
(52)
(27)
C (MHz)
(53)
(22)
DJ (kHz)
0.6127(12)
(153)
DJK (kHz)
(43)
(42)
DK (kHz)
-5.231(27)
(61)
d1 (kHz)
(11)
(69)
d2 (kHz)
(63)
(76)
HJK (Hz)
0.0347(16)
(140)
h2 (Hz)
(72)
(83)
h3 (Hz)
(33)
(140)
# of Lines
173 -
MW rms (kHz)
26.963
ν29
Ground state
ν17
Segmented Chirped-pulse Millimeter-wave Spectroscopy for Astrochemistry

15. Conclusions and Outlook
75 – 110 GHz segmented chirped-pulse rotational spectrometer
Organic molecules in the ISM
1,2-Propanediol
Isopropyl cyanide
Low frequency vibrations that are difficult to observe with IR spectroscopy
Exploration of conformers, excited states and isotopologues
New chamber
Electrical discharge and laser ablation apparatus
Chemical reactions and reaction mechanisms
Segmented Chirped-pulse Millimeter-wave Spectroscopy for Astrochemistry

16. Acknowledgements Thank you!
Segmented Chirped-pulse Millimeter-wave Spectroscopy for Astrochemistry

17. Max Planck Institute for the Structure and Dynamics of Matter
Segmented Chirped-pulse Millimeter-wave Spectroscopy for Astrochemistry
Benjamin E. Arenas1 Amanda L. Steber1,2 Sébastien Gruet1,2 Melanie Schnell1,2
1Max Planck Institute for Structure and Dynamics of Matter, Hamburg, Germany
2The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Hamburg, Germany
Max Planck Institute for the Structure and Dynamics of Matter