Project B8

@article{nokey,

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

author = {Oskar Asvany and Urs U. Graf and Weslley G. D. P. Silva and Lea Schneider and Slawa Kabanovic and Volker Ossenkopf-Okada and Jürgen Stutzki and Igor Savić and Rolf Güsten and Oliver Ricken and Bernd Klein and Stephan Schlemmer},

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 = {Philipp C. Schmid and Samuel J. P. Marlton and Weslley G. D. P. Silva and Thomas Salomon and János Sarka and Sven Thorwirth and Oskar Asvany and Stephan Schlemmer},

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^{+} (̃2Π)},

author = {Weslley G. D. P. Silva and Philipp C. Schmid and Divita Gupta and Sven Thorwirth and János Sarka and Oskar Asvany and Stephan Schlemmer},

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 = {Samuel J. P. Marlton and Philipp C. Schmid and Weslley G. D. P. Silva and Oskar Asvany and Stephan Schlemmer},

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), B = 1.39568(3), D = 2.27(9) × 10−5, γ = −0.07332(7), γD = 1.87(3) × 10−4, and the Fermi contact hyperfine constant for the HCN+ nitrogen atom bF = 0.0059(1). Based on this value, the Ã2Σ1/2+ state electronic wavefunction is estimated to have 11.5 ± 0.2% s orbital character. The spin–orbit coupling constant for the ̃ state was also determined with high precision ASO = −49.3122(4) cm−1. This work illustrates that leak-out spectroscopy can be applied to measure high-resolution spectra of low energy electronic transitions.},

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 = {Thomas Salomon and Weslley G. D. P. Silva and Sven Thorwirth and Oskar Asvany and Stephan Schlemmer},

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 = {Marcel Bast and Julian Böing and Thomas Salomon and Eline Plaar and Igor Savić and Mathias Schäfer and Oskar Asvany and Stephan Schlemmer and Sven Thorwirth},

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

isbn = {1089-5639},

year  = {2025},

date = {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 = {Divita Gupta and Philipp C. Schmid and Thomas Salomon and Oskar Asvany and Stephan Schlemmer},

doi = {10.1021/acsearthspacechem.5c00032},

year  = {2025},

date = {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{2025JMoSp.40711978B,

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

author = {Carlo Baddeliyanage and Joshua Karner and Sruthi Purushu Melath and Weslley G. D. P. Silva and Stephan Schlemmer and Oskar Asvany},

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 = {JoséLuis Doménech and Weslley G. D. P. Silva and Ernest A. Michael and Stephan Schlemmer and Oskar Asvany},

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

isbn = {1089-5639},

year  = {2024},

date = {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{Thorwirth2024,

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

author = {Sven Thorwirth and Kim Steenbakkers and Timon Danowski and Philipp C. Schmid and Luis Bonah and Oskar Asvany and Sandra Brünken and Stephan Schlemmer},

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 = {Kim Steenbakkers and Tom van Boxtel and Gerrit C. Groenenboom and Oskar Asvany and Britta Redlich and Stephan Schlemmer and Sandra Brünken},

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{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}

}