Laboratory astrochemistry at infrared wavelengths and molecular structure

• Applicant: Dr. Sven Thorwirth
• Subject Area: Astrophysics and Astronomy
• Term: from 2009 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 88839181

• Final Report Year: 2017

Final Report Abstract

Fortunately, quite a few of the original ideas have turned into reality over the funding period to “pay my debts”, for example, the isotopic spectroscopy of carbon rich clusters (C3 , SiC3 Si, C3 S, SC3 S), the high resolution spectroscopy of Si2 C finally culminating in its astronomical detection, the high-resolution infrared study of GeC3 Ge and the spectroscopic detection of several carbon-sulfur chains as long as SC7 S by similar techniques. An astronomical detection of Si2 C could not be expected at the beginning but its discovery during was very exciting indeed! In IRC+10216, Si2 C is found to be very abundant and to play a key role in the formation of silicon-carbon dust grains. The laboratory infrared detection of a cluster as complex as SC7 S was kind of a surprise but is a clear manifestation of the possibilities provided by high-resolution infrared spectroscopy of a free jet. For sure, other binary carbon-rich chain systems involving even more exotic elements than S and Si, are very interesting future targets. As we have shown through our study of GeCCCGe for example, high-resolution infrared spectroscopy can provide very important structural information for carbon-rich systems. Still, for many such fundamental systems virtually no spectroscopic and structural information is known from experiment. As we have shown at a later stage of the funding period, new areas like carbon clusters ions are very promising fields of research to be entered in the future. A first step into this direction was already successfully taken as shown through the detection of C3 + and HC3 O+ , studies that offer many more future possibilities. The collaboration with Dr. Michael C. McCarthy at Harvard University has permitted the detection of many highly interesting transient molecules. This branch of research performed here offers possibilities for subsequent radio astronomical searches. Many of the molecules are found to exhibit very interesting/exotic molecular structures and might even be considered as textbook examples for structural chemistry.

Publications

• Bonding in the Heavy Analogue of Hydrogen Cyanide: The Curious Case of Bridged HPSi, Angew. Chem. Int. Ed. 49, 5661 (2010)
  V. Lattanzi, S. Thorwirth, D. T. Halfen, L. A. Mück, L. M. Ziurys, P. Thaddeus, J. Gauss, and M. C. McCarthy
  
• A continuous-wave optical parametric oscillator around 5 micrometer wavelength for highresolution spectroscopy, Rev. Sci. Instrum. 82, 063105 (2011)
  J. Krieg, A. Klemann, I. Gottbehüt, S. Thorwirth, T. Giesen, and S. Schlemmer
  
• High-resolution OPO spectroscopy of Si2 C3 at 5µm: Observation of hot band transitions associated with ν3 , J. Mol. Spectrosc., 270, 75 (2011)
  S. Thorwirth, J. Krieg, V. Lutter, I. Keppeler, S. Schlemmer, M. E. Harding, J. Vázquez, and T. F. Giesen
  
• Silicon Oxysulfide, OSiS: Rotational Spectrum, Quantum-Chemical Calculations, and Equilibrium Structure, J. Phys. Chem. Lett. 2, 1228-1231 (2011)
  S. Thorwirth, L. A. Mück, J. Gauss, F. Tamassia, V. Lattanzi, and M. C. McCarthy
  
• Cyclic SiS2 - a new perspective on the Walsh rules, Angew. Chem. Int. Ed. 51, 3695-3698 (2012)
  L. A. Mück, V. Lattanzi, S. Thorwirth, M. C. McCarthy, and J. Gauss
  
• Two Isomers of Protonated Isocyanic Acid: Evidence for an Ion-Molecule Pathway for HNCO-HOCN Isomerization, J. Phys. Chem. Lett. 3, 3420-3424 (2012)
  V. Lattanzi, S. Thorwirth, C. A. Gottlieb, and M. C. McCarthy
  
• High-Resolution Spectroscopy of C3 around 3 µm, J. Phys. Chem. A 117, 3332-3339 (2013)
  J. Krieg, V. Lutter, C. P. Endres, I. Keppeler, P. Jensen, M. E. Harding, J. Vázquez, S. Schlemmer, T. F. Giesen, and S. Thorwirth
  
• Discovery of a missing link: Detection and structure of the elusive disilicon carbide cluster, J. Phys. Chem. Lett. 6, 2107-2111 (2015)
  M. C. McCarthy, J. H. Baraban, P. B. Changala, J. F. Stanton, M.-A. Martin-Drumel, S. Thorwirth, C. A. Gottlieb, and N. J. Reilly
  
• Discovery of SiCSi in IRC+10216: A missing link between gas and dust carriers of Si-C bonds, Astrophys. J. 806, L3 (2015)
  J. Cernicharo, M. C. McCarthy, C. A. Gottlieb, M. Agundez, L. Velilla Prieto, J. H. Baraban, P. B. Changala, M. Guelin, C. Kahane, M. A. Martin-Drumel, N. A. Patel, N. J. Reilly, J. F. Stanton, G. Quintana-Lacaci, S. Thorwirth, and K. H. Young
  
• Gas-phase spectroscopic detection and structural elucidation of carbon-rich group 14 binary clusters: Linear GeC3 Ge, J. Phys. Chem. A 120, 254-259 (2016)
  S. Thorwirth, V. Lutter, A. Javadi Javed, J. Gauss, and T. F. Giesen
  
• Carbon-sulfur chains: A high-resolution infrared and quantum-chemical study of C3S and SC7S, Int. J. Quantum Chem. 117, e25414 (2017)
  J. B. Dudek, T. Salomon, S. Fanghänel, and S. Thorwirth
  
• High-resolution infrared fingerprints of carbon-sulfur clusters: The ν1 band of C5S, Chem. Phys. Lett. 684, 262-266 (2017)
  S. Thorwirth, T. Salomon, S. Fanghänel, J. R. Kozubal and J. B. Dudek