Project B8

Project leaders: Schlemmer, Stephan (PH1); Thorwirth, Sven (PH1); Asvany, Oskar (PH1)

In this sub-project we want to record spectra of negative ions which are believed to play a role in the physics and chemistry of the interstellar medium. They are a sink for the electrons produced by cosmic ray ionisation and some anions have already been found in the ISM but their role in the chemical evolution of the ISM is not understood very well. For small species like deprotonated methanol, CH₃O^– , we aim for rotationally resolved vibrational spectra and pure rotational spectra with our unique action spectroscopy methods. Such anions should be present in the ISM based on the very high abundance of the parent molecule and it will therefore be possible to detect them in CRC based collaborations by their fingerprint rotational spectra. Likewise, infrared spectra of negatively charged medium sized hydrocarbons, in particular polycyclic aromatic hydrocarbons (PAHs), will be recorded to obtain a first account of the amount of negatively charged PAHs. A first prime target in this research will be the benzene anion (C₆H₆^– ) and also deprotonated benzene (C₆H₅^– ). Such a new step in ion spectroscopy is needed in the era of the JWST and ALMA telescopes which provide infrared and also far-infrared spectra in tremendous detail such that more anions will be found and their role can be investigated.

Publications

@article{2023A&A...680A..19C,

title = {Astronomical CH_{3}^{+} rovibrational assignments. A combined theoretical and experimental study validating observational findings in the d203-506 UV-irradiated protoplanetary disk},

author = {P. Bryan Changala and Ning L. Chen and Hai L. Le and Bérenger Gans and Kim Steenbakkers and Thomas Salomon and Luis Bonah and Ilane Schroetter and Amélie Canin and Marie-Aline Martin-Drumel and Ugo Jacovella and Emmanuel Dartois and Séverine Boyé-Péronne and Christian Alcaraz and Oskar Asvany and Sandra Brünken and Sven Thorwirth and Stephan Schlemmer and Javier R. Goicoechea and Gaël Rouillé and Ameek Sidhu and Ryan Chown and Dries Van De Putte and Boris Trahin and Felipe Alarcón and Olivier Berné and Emilie Habart and Els Peeters},

doi = {10.1051/0004-6361/202347765},

year  = {2023},

date = {2023-12-01},

urldate = {2023-12-01},

journal = {Astronomy & Astrophysics},

volume = {680},

pages = {A19},

key = {B8,C4},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

References

1. Asvany and Schlemmer, “Rotational action spectroscopy of trapped molecular ions”, Phys. Chem. Chem. Phys. 23, 26602 (2021).
2. Brünken, Sipilä, Chambers, Harju, Caselli, Asvany, Honingh, Kamin ́ski, et al., “H2D+ observations give an age of at least one million years for a cloud core forming Sun-like stars”, Nature 516, 219 (2014).
3. Brünken, Kluge, Stoffels, Asvany, and Schlemmer, “Laboratory Rotational Spectrum of l-C₃H⁺ and Confirmation of its Astronomical Detection”, ApJ Letters 783, L4 (2014).
4. Doménech, Jusko, Schlemmer, and Asvany, “The First Laboratory Detection of Vibration-rotation Tran- sitions of 12CH+ and 13CH+ and Improved Measurement of Their Rotational Transition Frequencies”, ApJ 857, 61 (2018).
5. Doménech, Schlemmer, and Asvany, “Accurate rotational rest frequencies for ammonium ion isotopo- logues”, ApJ 866, 158 (2018).
6. Jusko, Asvany, Wallerstein, Brünken, and Schlemmer, “Two photon rotational action spectroscopy of cold OH at 1 ppb accuracy”, Phys. Rev. Lett. 112, 253005 (2014).
7. Jusko, Stoffels, Thorwirth, Brünken, Schlemmer, and Asvany, “High-resolution vibrational and rota- tional spectroscopy of CD₂H⁺ in a cryogenic ion trap”, J. Mol. Spectrosc. 332, 59 (2017).
8. McGuire, Asvany, Brünken, and Schlemmer, “Laboratory spectroscopy techniques to enable observa- tions of interstellar ion chemistry”, Nat. Rev. Phys. 2, 402 (2020).
9. Schmid, Asvany, Salomon, Thorwirth, and Schlemmer, “Leak-out Spectroscopy, a universal method of action spectroscopy in cold ion traps”, J. Phys. Chem. A 126, 8111 (2022).
10. Thorwirth, Schreier, Salomon, Schlemmer, and Asvany, “Pure Rotational Spectrum of CN⁺”, ApJ Letters 882, L6 (2019).