Project C4

@article{2026arXiv260507995K,

title = {Space as a spectroscopic laboratory: High-resolution spectroscopy of the [^{13}C II] hyperfine structure with SOFIA/upGREAT},

author = {Kabanovic, S. and Ossenkopf-Okada, V. and Schlemmer, S. and Stutzki, J. and Schneider, N. and Graf, U. U. and Asvany, O. and Riechers, D. A. and Guevara, C. and Higgins, R. and Simon, R. and Okada, Y. and Mertens, M. and Schneider, L. and Güsten, R. and Tielens, A. G. G. M.},

url = {https://doi.org/10.1051/0004-6361/202659546},

doi = {10.1051/0004-6361/202659546},

year  = {2026},

date = {2026-06-01},

urldate = {2026-06-01},

journal = {A&A},

volume = {710},

pages = {L25},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Revisiting the J = 1 ← 0 fundamental rotational transition of HHe+ with action spectroscopy},

author = {Asvany, O. and Graf, U. U. and Silva, W. G. D. P. and Schneider, L. and Kabanovic, S. and Ossenkopf-Okada, V. and Stutzki, J. and Savić, I. and Güsten, R. and Ricken, O. and Klein, B. and Schlemmer, S.},

doi = {10.1039/D5CP04689K},

year  = {2026},

date = {2026-01-27},

urldate = {2026-01-27},

journal = {PCCP},

volume = {28},

pages = {4662-4667},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{D5CP04201A,

title = {High-resolution spectroscopy of [H,C,N]^{+}: I. Rotationally resolved vibrational bands of HCN^{+} and HNC^{+}},

author = {Schmid, P. C. and Marlton, S. J. P. and Silva, W. G. D. P. and Salomon, T. and Sarka, J. and Thorwirth, S. and Asvany, O. and Schlemmer, S.},

doi = {10.1039/D5CP04201A},

year  = {2026},

date = {2026-01-01},

urldate = {2026-01-01},

journal = {Phys. Chem. Chem. Phys.},

volume = {28},

issue = {7},

pages = {4394-4404},

publisher = {The Royal Society of Chemistry},

abstract = {Rovibrational spectra of the open-shell linear cations HCN+ (̃2Π) and HNC+ (̃2Σ+) are measured with leak-out spectroscopy in cryogenic 22-pole ion traps. The fundamental ν1 C–H stretching vibration of HCN+ is found at 3056.3412(1) cm−1 and the lower energy Renner–Teller (RT) component (Σ) of the ν1 + ν2 combination band is found at 3340.8480(2) cm−1. The resulting effective RT vibrational frequency of ≈300 cm−1 inferred from the comparison of these two bands indicates a large Renner–Teller splitting for HCN+. For HNC+, the ν1 N–H stretching vibration is found at 3407.9136(4) cm−1, much higher than expected from previous matrix work. Thanks to the rotational resolution of these infrared measurements, spectroscopic constants for the electronic fine-structure, molecular rotation, centrifugal distortion, Λ-doubling and spin-rotation interaction have been determined for the vibrational ground and excited states with high confidence. The infrared spectrum of HCN+ is rather rich and contains more bands including, e.g., the electronic à ← ̃ transition. The analysis of this band and the pure rotational spectrum of HCN+ will be the subject of further publications.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{D5CP04204F,

title = {High-resolution spectroscopy of [H,C,N]^{+}: II. Ground state rotational spectrum of HCN^{+}},

author = {Silva, W. G. D. P. and Schmid, P. C. and Gupta, D. and Thorwirth, S. and Sarka, J. and Asvany, O. and Schlemmer, S.},

url = {http://dx.doi.org/10.1039/D5CP04204F},

doi = {10.1039/D5CP04204F},

year  = {2026},

date = {2026-01-01},

urldate = {2026-01-01},

journal = {Phys. Chem. Chem. Phys.},

volume = {28},

issue = {7},

pages = {4405-4411},

publisher = {The Royal Society of Chemistry},

abstract = {The rotational spectrum of HCN+ has been measured between 270 and 520 GHz in a cryogenic ion trap instrument employing a double resonance vibrational-rotational scheme based on leak-out spectroscopy. A total of four transitions with quantum numbers ranging from J″ = 2.5 to 5.5 have been observed for the lowest-energy spin–orbit state 2Π3/2 of this open-shell cation, which has an inverted 2Π electronic ground state. The transitions show well-resolved Λ-doubling components each displaying complex hyperfine splittings due to the presence of two nuclei with non-zero spins, 1H (I = 1/2) and 14N (I = 1). The accurate transition frequencies and ground state spectroscopic parameters determined for HCN+ in this work will enable radio astronomical searches of this important cation in the interstellar medium.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{D5CP04255K,

title = {High-resolution spectroscopy of [H,C,N]^{+}: III. Infrared Ã2Σ^{+} ← ̃2Π electronic transition of HCN^{+}},

author = {Marlton, S. J. P. and Schmid, P. C. and Silva, W. G. D. P. and Asvany, O. and Schlemmer, S.},

doi = {10.1039/D5CP04255K},

year  = {2026},

date = {2026-01-01},

urldate = {2026-01-01},

journal = {Phys. Chem. Chem. Phys.},

volume = {28},

issue = {7},

pages = {4412-4421},

publisher = {The Royal Society of Chemistry},

abstract = {The Ã2Σ+ ← ̃2Π electronic transition of the fundamental HCN+ ion is reported. The spectrum exhibits a rotational, fine, and hyperfine structure that provides insights into the geometries and wavefunctions of the Ã2Σ+ and ̃2Π states. The extracted spectroscopic constants for the à state include (in cm−1) Te = 3238.8224(2)},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{silva2026hyperfineresolved,

title = {Hyperfine-resolved rovibrational and rotational spectroscopy of OH^{+}},

author = {Silva, W. G. D. P. and Schneider, L. and Graf, U. U. and Müller, H. S. P. and Jusko, P. and Jacob, A. M. and Riechers, D. A. and Schlemmer, S. and Asvany, O.},

url = {https://arxiv.org/abs/2605.12102},

doi = {10.1039/D6CP00632A},

year  = {2026},

date = {2026-01-01},

urldate = {2026-01-01},

journal = {Physical Chemistry Chemical Physics},

volume = {28},

number = {20},

pages = {12651-12659},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{cite-keyh,

title = {High Resolution Leak-Out Spectroscopy of the ν2 Symmetric CH_{3} Stretching Mode of Protonated Acetonitrile, CH_{3}CNH^{+}},

author = {Salomon, T. and Silva, W. G. D. P. and Thorwirth, S. and Asvany, O. and Schlemmer, S.},

doi = {10.1021/acs.jpca.5c06360},

isbn = {1089-5639},

year  = {2025},

date = {2025-12-23},

urldate = {2025-12-23},

journal = {The Journal of Physical Chemistry A},

volume = {130},

number = {1},

pages = {88–95},

publisher = {American Chemical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{cite-keyf,

title = {Spectroscopic Detection and Characterization of Cyanooxomethylium, NCCO^{+}},

author = {Bast, M. and Böing, J. and Salomon, T. and Plaar, E. and Savić, I. and Schäfer, M. and Asvany, O. and Schlemmer, S. and Thorwirth, S.},

doi = {10.1021/acs.jpca.5c06273},

isbn = {1089-5639},

year  = {2025},

date = {2025-11-20},

urldate = {2025-11-20},

journal = {The Journal of Physical Chemistry A},

volume = {129},

number = {48},

pages = {11136–11144},

publisher = {American Chemical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{cite-keyg,

title = {Rotationally Resolved Spectrum of the Degenerate Antisymmetric C–H Stretching Band of c-C3H3^{+}},

author = {Gupta, D. and Schmid, P. C. and Salomon, T. and Asvany, O. and Schlemmer, S.},

doi = {10.1021/acsearthspacechem.5c00032},

year  = {2025},

date = {2025-04-02},

urldate = {2025-04-02},

journal = {ACS Earth and Space Chemistry},

volume = {9},

number = {4},

pages = {952–958},

publisher = {American Chemical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2025PCCP...27.4826S,

title = {High-resolution leak-out spectroscopy of HHe_{2}^{+}},

author = {Salomon, T. and Baddeliyanage, C. and Schladt, C. and Simkó, I. and Császár, A. G. and Silva, W. G. D. P. and Schlemmer, S. and Asvany, O.},

doi = {10.1039/D4CP04767B},

year  = {2025},

date = {2025-02-01},

urldate = {2025-02-01},

journal = {Physical Chemistry Chemical Physics (Incorporating Faraday Transactions)},

volume = {27},

number = {9},

pages = {4826-4828},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2025JMoSp.40711978B,

title = {Extending the laboratory rotational spectrum of linear C_{3}H^{+}},

author = {Baddeliyanage, C. and Karner, J. and Melath, S. P. and Silva, W. G. D. P. and Schlemmer, S. and Asvany, O.},

doi = {10.1016/j.jms.2024.111978},

year  = {2025},

date = {2025-01-01},

urldate = {2025-01-01},

journal = {Journal of Molecular Spectroscopy},

volume = {407},

pages = {111978},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{cite-keyi,

title = {High Resolution Rovibrational Spectroscopy of the ν6 and ν3 + ν7 Bands of H_{3}CCCH^{+}},

author = {Doménech, J. L. and Silva, W. G. D. P. and Michael, E. A. and Schlemmer, S. and Asvany, O.},

doi = {10.1021/acs.jpca.4c03628},

isbn = {1089-5639},

year  = {2024},

date = {2024-11-22},

urldate = {2024-11-22},

journal = {The Journal of Physical Chemistry A},

volume = {128},

number = {48},

pages = {10322–10327},

publisher = {American Chemical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Silva2024,

title = {Hyperfine-resolved rotational spectroscopy of HCNH^{+}},

author = {Silva, W. G. D. P. and Bonah, L. and Schmid, P. C. and Schlemmer, S. and Asvany, O.},

doi = {10.1063/5.0185365},

issn = {1089-7690},

year  = {2024},

date = {2024-02-21},

urldate = {2024-02-21},

journal = {physics.chem-ph},

volume = {160},

number = {7},

publisher = {AIP Publishing},

abstract = {<jats:p>The rotational spectrum of the molecular ion HCNH+ is revisited using double-resonance spectroscopy in an ion trap apparatus, with six transitions measured between 74 and 445 GHz. Due to the cryogenic temperature of the trap, the hyperfine splittings caused by the 14N quadrupolar nucleus were resolved for transitions up to J = 4 ← 3, allowing for a refinement of the spectroscopic parameters previously reported, especially the quadrupole coupling constant eQq.</jats:p>},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Thorwirth2024,

title = {Gas-Phase Infrared Action Spectroscopy of CH2Cl^{+} and CH3ClH^{+}: Likely Protagonists in Chlorine Astrochemistry},

author = {Thorwirth, S. and Steenbakkers, K. and Danowski, T. and Schmid, P. C. and Bonah, L. and Asvany, O. and Brünken, S. and Schlemmer, S.},

doi = {10.3390/molecules29030665},

issn = {1420-3049},

year  = {2024},

date = {2024-02-00},

urldate = {2024-02-00},

journal = {Molecules},

volume = {29},

number = {3},

publisher = {MDPI AG},

abstract = {<jats:p>Two fundamental halocarbon ions, CH2Cl+ and CH3ClH+, were studied in the gas phase using the FELion 22-pole ion trap apparatus and the Free Electron Laser for Infrared eXperiments (FELIX) at Radboud University, Nijmegen (the Netherlands). The vibrational bands of a total of four isotopologs, CH235,37Cl+ and CH335,37ClH+, were observed in selected wavenumber regions between 500 and 2900 cm−1 and then spectroscopically assigned based on the results of anharmonic force field calculations performed at the CCSD(T) level of theory. As the infrared photodissociation spectroscopy scheme employed probes singly Ne-tagged weakly bound complexes, complementary quantum-chemical calculations of selected species were also performed. The impact of tagging on the vibrational spectra of CH2Cl+ and CH3ClH+ is found to be virtually negligible for most bands; for CH3ClH+–Ne, the observations suggest a proton-bound structural arrangement. The experimental band positions as well as the best estimate rotational molecular parameters given in this work provide a solid basis for future spectroscopic studies at high spectral resolutions.</jats:p>},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Steenbakkers2024,

title = {Leak-out spectroscopy as alternative method to rare-gas tagging for the Renner–Teller perturbed HCCH^{+} and DCCD^{+} ions},

author = {Steenbakkers, K. and van Boxtel, T. and Groenenboom, G. C. and Asvany, O. and Redlich, B. and Schlemmer, S. and Brünken, S.},

doi = {10.1039/d3cp04989b},

issn = {1463-9084},

year  = {2024},

date = {2024-01-17},

urldate = {2024-01-17},

journal = {Phys. Chem. Chem. Phys.},

volume = {26},

number = {3},

pages = {2692–2703},

publisher = {Royal Society of Chemistry (RSC)},

abstract = {<jats:p>Vibronic coupling effects in the low-lying bending modes of the open-shell linear ions HCCH<jats:sup>+</jats:sup> and DCCD<jats:sup>+</jats:sup> have been investigated using cryogenic infrared action spectroscopy in combination with a free electron laser.</jats:p>},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Silva17082024,

title = {High resolution rovibrational and rotational spectroscopy of H_{2}CCCH^{+}},

author = {Silva, W. G. D. P. and Gupta, D. and Plaar, E. and Doménech, J. L. and Schlemmer, S. and Asvany, O.},

doi = {10.1080/00268976.2023.2296613},

year  = {2024},

date = {2024-01-01},

urldate = {2024-01-01},

journal = {Molecular Physics},

volume = {122},

number = {15-16},

pages = {e2296613},

publisher = {Taylor & Francis},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@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 = {Changala, P. B. and Chen, N. L. and Le, H. L. and Gans, B. and Steenbakkers, K. and Salomon, T. and Bonah, L. and Schroetter, I. and Canin, A. and Martin-Drumel, M.-A. and Jacovella, U. and Dartois, E. and Boyé-Péronne, S. and Alcaraz, C. and Asvany, O. and Brünken, S. and Thorwirth, S. and Schlemmer, S. and Goicoechea, J. R. and Rouillé, G. and Sidhu, A. and Chown, R. and Van De Putte, D. and Trahin, B. and Alarcón, F. and Berné, O. and Habart, E. and Peeters, E.},

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}

}

@article{2023JMoSp.39811840B,

title = {Ro-vibrational spectra of C–C stretching modes of C_{3}H^{+} and HC_{3}O^{+}},

author = {Bast, M. and Böing, J. and Salomon, T. and Thorwirth, S. and Asvany, O. and Schäfer, M. and Schlemmer, S.},

doi = {10.1016/j.jms.2023.111840},

year  = {2023},

date = {2023-11-01},

urldate = {2023-11-01},

journal = {Journal of Molecular Spectroscopy},

volume = {398},

pages = {111840},

keywords = {},

pubstate = {published},

tppubtype = {article}

}