| Summary: | 碩士 === 國立臺灣大學 === 物理學系 === 85 === In the first part of this thesis, the absorption spectra
of Chlorophyll a (Chl a) in non-polar solvents are
taken for the study of aggregation of Chl a.
Concentration- and time-dependent experiments are performed
on several polar and non-polar solvents. The Gibbs free energy
of dimerization of Chl a are calculated. Some discussion for
the unwelcome hydration are also given at the end of this
part. Femtosecond laser
sources are powerful tools for the study of ultra-fastphenomena
on picosecond and sub-picosecond time scales. Thus it can be
used to study the vibrational motions and their relaxation
mechanisms, both dephasing and relaxation, of polyatomic
molecules. Therefore, in the second part, we use a ultra-fast
laser source to study the vibrational motions and the relative
phenomena of a cyanine dye HDITCP solution.
A Ti:sapphire femtosecond pulse laser is used to excite and
probe HDITCPdye molecules. Incorporating with an optical delay
line and Lock-In technique, we build a pump-probe
measurements setup in our laboratory. Then we execute a series
of wavelength-dependent one-color-pump-probe measurements from
780---860 nm. The vibration motions and their dephasing are
observed in these experiments. The possible mechanisms
governing this phenomena are alsodeduced.
Finally, conclusion and future studies on these two experiments
are proposed at the end of this thesis.
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