High resolution microwave and infrared spectroscopy of four-membered heterocyclic compounds
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Date
2009, 2011, 2012, 2012, 2010, 2011
Authors
Chen, Ziqiu
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Elsevier
Elsevier
American Chemical Society
Elsevier
American Chemical Society
Elsevier
Elsevier
American Chemical Society
Elsevier
American Chemical Society
Abstract
High resolution molecular spectroscopic techniques are useful tools to accurately probe energy differences between quantum states of molecules. These energy levels are inherently dependent on the underlying potential functions, which ultimately govern the structures and dynamics of molecules. Thus, the detailed characterization of potential energy profiles through molecular spectroscopy provides important information about molecular properties. Given the increased structural and dynamic complexity of large molecules, small compounds serve as excellent prototypes to establish quantum mechanical models that accurately characterize quantum states and ultimately potential energy functions of various molecular classes. This thesis describes the use of rotational and rovibrational spectroscopy to probe one such class: four-membered heterocycles.
Rotationally-resolved vibrational spectra of four-membered rings including β-propiolactone (c-C3H4O2), 3-oxetanone (c-C3H4O2), azetidine (c-C3H6N) and silacyclobutane (c-C3H8Si) were recorded below 1200 cm-1 using a Fourier transform infrared spectrometer (FTIR) with synchrotron light at the far infrared beamline of the Canadian Light Source (CLS). Additionally, Fourier transform microwave (FTMW) spectroscopy was used to study the pure rotational spectra of β-propiolactone and silacyclobutane for the first time. This allowed the accurate characterization of the ground vibrational state and molecular structure in support of the rovibrational analysis.
The far infrared vibrational modes of these four molecules were analyzed individually initially and followed by a global fit of all observed transitions of each molecule. Unique spectroscopic signatures arising from Coriolis coupling(β-propiolactone, 3-oxetanone), tunneling motions (azetidine, silacyclobutane) and the large amplitude ring puckering vibration (3-oxetanone, azetidine, silacyclobutane) were revealed and treated. The resultant Hamiltonian models used for each molecule account for the observed spectra as the spectroscopic constants are consistent across the ground state and all vibrationally excited states studied. Collectively, these studies have provided a highly effective working protocol for the treatment of high resolution rovibrational data to model the dynamic behaviour of real molecules.
Description
Keywords
Spectroscopy, High resolution, Synchrotron, Physical chemistry, Heterocyclic compounds
Citation
Z. Chen and J. van Wijngaarden, Journal of Molecular Spectroscopy, 257 (2009) 164–169
Z. Chen and J. van Wijngaarden, Journal of Molecular Spectroscopy, 268 (2011) 107-111
Z. Chen and J. van Wijngaarden, Journal of Molecular Spectroscopy, 279 (2012) 31–36
Z. Chen and J. van Wijngaarden, Journal of Physical Chemistry A, 116 (2012) 9490-9496
T. Zaporozan, Z. Chen and J. van Wijngaarden, Journal of Molecular Spectroscopy, 264 (2010) 105-110
J. van Wijngaarden, Z. Chen, C. W. van Dijk and J. L. Sorensen, Journal of Physical Chemistry A, 115 (2011) 8650-8655
Z. Chen and J. van Wijngaarden, Journal of Molecular Spectroscopy, 268 (2011) 107-111
Z. Chen and J. van Wijngaarden, Journal of Molecular Spectroscopy, 279 (2012) 31–36
Z. Chen and J. van Wijngaarden, Journal of Physical Chemistry A, 116 (2012) 9490-9496
T. Zaporozan, Z. Chen and J. van Wijngaarden, Journal of Molecular Spectroscopy, 264 (2010) 105-110
J. van Wijngaarden, Z. Chen, C. W. van Dijk and J. L. Sorensen, Journal of Physical Chemistry A, 115 (2011) 8650-8655