عنوان
پدید آورنده
موضوع
رده
کتابخانه
محل استقرار
شماره کتابشناسی ملی
شماره
TLpq304303126
زبان اثر
زبان متن نوشتاري يا گفتاري و مانند آن
انگلیسی
عنوان و نام پديدآور
عنوان اصلي
The effect of pH and solvent on the photophysics of thymine
نام عام مواد
[Thesis]
نام نخستين پديدآور
A. M. Abdallah
وضعیت نشر و پخش و غیره
نام ناشر، پخش کننده و غيره
King Fahd University of Petroleum and Minerals (Saudi Arabia)
تاریخ نشرو بخش و غیره
1996
مشخصات ظاهری
نام خاص و کميت اثر
95
یادداشتهای مربوط به پایان نامه ها
جزئيات پايان نامه و نوع درجه آن
M.S.
کسي که مدرک را اعطا کرده
King Fahd University of Petroleum and Minerals (Saudi Arabia)
امتياز متن
1996
یادداشتهای مربوط به خلاصه یا چکیده
متن يادداشت
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.
موضوع (اسم عام یاعبارت اسمی عام)
موضوع مستند نشده
Biochemistry
موضوع مستند نشده
Chemistry
موضوع مستند نشده
Pure sciences
نام شخص به منزله سر شناسه - (مسئولیت معنوی درجه اول )
مستند نام اشخاص تاييد نشده
A. M. Abdallah
دسترسی و محل الکترونیکی
نام الکترونيکي
مطالعه متن کتاب وضعیت انتشار
فرمت انتشار
p
اطلاعات رکورد کتابشناسی
نوع ماده
[Thesis]
کد کاربرگه
276903
اطلاعات دسترسی رکورد
سطح دسترسي
a
تكميل شده
Y
