Quantum monodromy in NCNCS - direct experimental confirmation.

Autor: Tokaryk DW; Department of Physics, University of New Brunswick, P.O. Box 4400, Fredericton, New Brunswick E3B 5A3, Canada. DTokaryk@UNB.Ca., Ross SC; Department of Physics, University of New Brunswick, P.O. Box 4400, Fredericton, New Brunswick E3B 5A3, Canada. DTokaryk@UNB.Ca., Winnewisser M; Department of Physics, The Ohio State University, Columbus, Ohio, 43210-1106, USA., Winnewisser BP; Department of Physics, The Ohio State University, Columbus, Ohio, 43210-1106, USA., De Lucia FC; Department of Physics, The Ohio State University, Columbus, Ohio, 43210-1106, USA., Billinghurst BE; Canadian Light Source Inc., University of Saskatchewan, 44 Innovation Blvd., Saskatoon, Saskatchewan S7N 3V3, Canada.
Jazyk: angličtina
Zdroj: Physical chemistry chemical physics : PCCP [Phys Chem Chem Phys] 2023 Jul 19; Vol. 25 (28), pp. 18659-18678. Date of Electronic Publication: 2023 Jul 19.
DOI: 10.1039/d3cp01420g
Abstrakt: Since the first confirmation of quantum monodromy in NCNCS (B. P. Winnewisser et al. , Report No. TH07 in 60th International Symposium on Molecular Spectroscopy, Columbus, OH, (2005) and B. P. Winnewisser et al. , Phys. Rev. Lett. , 2005, 95 , 243002) we have continued to explore its implications for the quantum structure of molecules. To confirm quantum monodromy bending-vibrational + axial-rotational quantum energy level information is needed. This was not directly available from the pure a-type rotational transitions available in 2005. The confirmation of quantum monodromy therefore had to be based on the fitting of the Generalised SemiRigid Bender (GSRB) model to the experimental rotational data. The GSRB is a physically motivated model and was able to extract the required information based on the changes of the rotational energy level structure upon excitation of the bending vibration and of the axial rotation. These results were, in some sense, predictions. Our goal here was to obtain a fully experimental and unambigous confirmation of quantum monodromy in NCNCS. This involved a series of experimental campaigns at the Canadian Light Source (CLS) synchrotron. To coax the required information out of the masses of spectral data that had been obtained a variety of techniques had to be used. The result is that we can now confirm, without recourse to a theoretical model, the existence of quantum monodromy in the ν 7 bending mode of NCNCS. As a side benefit we also confirm the power of the GSRB model to extract the required information from the previously available data. The predictions previously provided by the GSRB were surprisingly accurate. Only a slight augmentation of the model was required to allow us to refit it including the new data, while maintaining the quality of the fitting for that data previously available. We also present a very basic introduction to the idea of monodromy and to how the GSRB was used.
Databáze: MEDLINE