The structures, vibrational frequencies, and potential energy functions of several
molecules in their ground and excited electronic states were determined using various
spectroscopic and theoretical methods.
High-level ab initio and density functional theory (DFT) calculations were
utilized to investigate the previously reported structures and vibrational spectra of 1,3-
disilacyclobutane (13DSCB) and its 1,1,3,3-d4 (13DSCB-d4) isotopomer. These
calculations confirmed the finding from earlier microwave work that the CSiC angles of
the 13DSCB ring are unexpectedly larger than the SiCSi angles. The calculated
vibrational spectra using density functional theory agreed well with the experimental
data and showed CH2 modes to have unusually low values. The calculations also
confirmed that the individual molecules in the vapor phase are puckered whereas in the
solid they become planar.
The one-dimensional potential energy surfaces (PESs) for the ring inversion
vibration of 2-cyclohexen-1-one and its 2,6,6-d3 isotopomer in its ground and singlet
S1(n,π*) electronic states were determined using ultraviolet cavity ringdown
spectroscopy (CRDS). The CRDS data allowed several of the quantum states of the ring
inversion vibration to be determined for both the ground and excited electronic states,
and the data were fit very well with PESs with high barriers to inversion. The infrared
and Raman spectra and DFT calculations were utilized to complete a vibrational
assignment of 2CHO and 2CHO-d3. A remarkable agreement was seen between the
experimental and calculated spectra.
The fluorescence excitation spectra (FES) and the single-vibronic level
fluorescence (SVLF) spectra of jet-cooled 1,4-dihydronaphthalene (14DHN) were acquired to determine its ring-puckering potential energy function for the ground and
singlet S1(π,π*) electronic states. Ultraviolet, infrared, and Raman spectra were also
recorded to complement the analysis. The potential energy functions showed that the
molecule is planar in both the ground and S1(π,π*) states. A complete vibrational
assignment was carried out for 14DHN using the infrared and Raman data and aided by
DFT calculations.
The ab intio calculations carried out on 2-methyl-2-cyclopenten-1-one (2MCP)
showed that the molecule can have 3 different conformers. Infrared and Raman spectra
of the liquid-phase molecule were recorded and analyzed to complement the theoretical
calculations.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2030 |
| Date | 15 May 2009 |
| Creators | Rishard, Mohamed Zuhair Mohamed |
| Contributors | Laane, Jaan |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | thesis, text |
| Format | electronic, application/pdf, born digital |
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