عنوان
پدید آورنده
موضوع
رده
کتابخانه
محل استقرار
NATIONAL BIBLIOGRAPHY NUMBER
Number
TLpq304303126
LANGUAGE OF THE ITEM
.Language of Text, Soundtrack etc
انگلیسی
TITLE AND STATEMENT OF RESPONSIBILITY
Title Proper
The effect of pH and solvent on the photophysics of thymine
General Material Designation
[Thesis]
First Statement of Responsibility
A. M. Abdallah
.PUBLICATION, DISTRIBUTION, ETC
Name of Publisher, Distributor, etc.
King Fahd University of Petroleum and Minerals (Saudi Arabia)
Date of Publication, Distribution, etc.
1996
PHYSICAL DESCRIPTION
Specific Material Designation and Extent of Item
95
DISSERTATION (THESIS) NOTE
Dissertation or thesis details and type of degree
M.S.
Body granting the degree
King Fahd University of Petroleum and Minerals (Saudi Arabia)
Text preceding or following the note
1996
SUMMARY OR ABSTRACT
Text of Note
The effect of pH and various alcohol-water mixtures on the electronic spectra and excited state dynamics of thymine, one of the DNA constituents, have been investigated. A mode-locked Nd:YAG laser in combination with a cavity-dumped synchronously-pumped dye laser is used as a source of excitation. Fluorescence decay and time-resolved spectra were recorded with picosecond photon counting spectrometer. Steady-state fluorescence spectra as well as ultraviolet absorption spectra were also recorded. Fluorescence spectra of thymine in aqueous solutions where thymine exists in the neutral form have been found to vary in shape as the excitation wavelength is increased. This change in shape is explained by the presence of another tautomer beside the predominant diketo tautomer of thymine. This minor tautomer is believed to be 5-methyl-2-hydoxy-4(3H)-pyrimidinone or the keto-enol tautomer. Lifetime analysis of fluorescence decays support this explanation where a biexponential decay with lifetimes of around 0.7 and 4 ns is observed for the neutral form of thymine. Time-resolved spectra are in accordance with this explanation. Fluorescence lifetimes of thymine do not vary in methanol-water and ethanol-water mixtures. While the lifetime of the keto-enol tautomer is found to vary with viscosities of the 1-propanol-water mixtures. This is explained by solvent-solvent and solute-solvent interaction. According to the steady-state and time-resolved fluorescence spectra in the various alcohol-water mixtures, thymine does nor undergo a pKa shift in the excited state.
TOPICAL NAME USED AS SUBJECT
Biochemistry
Chemistry
Pure sciences
PERSONAL NAME - PRIMARY RESPONSIBILITY
A. M. Abdallah
ELECTRONIC LOCATION AND ACCESS
Electronic name
مطالعه متن کتاب p
[Thesis]
276903
a
Y
