Schnippering, Mathias (2009) Development and application of evanescent wave cavity ring-down spectroscopy for studies of electrochemical and interfacial processes. PhD thesis, University of Warwick.

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Abstract

This thesis is concerned with the application of evanescent wave
cavity ring-down spectroscopy (EW-CRDS) and evanescent wave
broadband cavity enhanced absorption spectroscopy (EW-BB-CEAS) for
studies of electrochemical and interfacial processes. These include
nanoparticle adsorption/dissolution, polymer nanoparticle formation and
surface-bound electrochemical redox reactions. Different experimental
setups have been designed to investigate these systems.
EW-CRDS is a surface sensitive technique, which allows
absorption measurements at solid/liquid and solid/air interfaces. Surface
reactions can easily be monitored in real time. A pulsed or modulated laser
beam is coupled into an optical cavity which consists of at least one optical
element, in which the beam is total internal reflected. At the position of
total internal reflection (TIR), an evanescent field is established with the
amplitude decaying exponentially with distance from the boundary. The
evanescent field can be exploited to investigate the absorbance properties
of the liquid phase in the first few hundred nanometres of the solution
above the silica surface. These types of instruments have high temporal
resolution (up to 2 kHz repetition rate), coupled with high sensitivity
(minimum detectable interfacial absorbance per pass: ~80 ppm) which
enables the investigation of a variety of processes relating to fundamental
questions in the field of physical chemistry and materials science. The
aforementioned sensitivity and resolution make EW-CRDS an ideal tool
for those investigations, especially if combined with other techniques such
as electrochemistry or microfluidic and hydrodynamic techniques. In this
thesis, different instrumentational setups will be discussed.
EW-BB-CEAS is another example for a TIR based absorption
spectroscopic technique and can give additional spectral information about
the investigated surface processes by employing broadband light such as
supercontinuum radiation. In this case, the amplified light intensity within
the optical cavity is measured rather than the light decay.
By employing complementary techniques, such as electrochemistry
and atomic force microscopy and by fitting experimental data using finite-element
modelling, surface processes can not only be described accurately
but also kinetic information such as rate constants for the aforementioned
systems can be calculated.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QD Chemistry
Library of Congress Subject Headings (LCSH):	Cavity-ringdown spectroscopy, Surface chemistry, Absorption spectra
Official Date:	December 2009
Dates:	Date Event December 2009 Submitted
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Unwin, Patrick R.
Extent:	xix, 176 leaves : ill., charts
Language:	eng
URI:	http://wrap.warwick.ac.uk/id/eprint/3787

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