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Characterization of Electronic States of Volatile Anaesthetics by Electron Energy Loss Spectroscopy and Synchrotron Radiation
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Volatile anaesthetics are widely used in clinical practice to induct and maintain anaesthesia
through inhalation. The major atmospheric effects that may arise from emission
of volatile anaesthetics are their contributions to ozone depletion in the stratosphere and
to greenhouse global warming. In this thesis we present spectroscopic studies on UVradiation
and electron interaction with three of the volatile anaesthetics currently in use,
sevoflurane (C4H3F7O), isoflurane (C3H2ClF5O) and halothane (C2HBrClF3), in order
to comprehensively describe the underlying molecular mechanisms of these molecules yielding
dissociation. Electron scattering elastic differential cross sections (DCS) by the three
mentioned molecules were measured for energies from 8.0 eV to 50 eV. The experimental
DCSs and integral cross sections (ICSs) were compared with theoretical calculations,
performed by collaborating groups, using two different methodologies, the Schwinger multichannel
method (SMC) and the independent atom model–screening corrected additivity
rule (IAM-SCAR). Moreover, we present, for the same compounds, results from VUV
photoabsorption measurements over the wavelength range 115-220 nm, together with ab
initio theoretical calculations of the vertical excitation energies and oscillator strength.
This combined experimental and theoretical study allows a comprehensive description
and characterization of the electronic states of these chemical compounds. The measured
photoabsorption cross sections were also used to calculate the photolysis lifetime of the
molecules in the Earth’s atmosphere from ground level up to the limit of the stratopause.
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Electron scattering VUV photoabsorption isoflurane sevoflurane halothane