Photo bleaching spectroscopic studies and lifetime measurements of fluorescent organic dyes

العناوين الأخرى

دراسات القصر البصري الطيفية و حسابات زمن عمر التألق للصبغات العضوية

مقدم أطروحة جامعية

Ali, Qusayy Raghib

مشرف أطروحة جامعية

Chiad, Baha Tumah
al-Wattar, Abbas Jasim Hammadi

أعضاء اللجنة

Dhahir, Muhammad K.
Mahdi, Bushrah Razzuqi
Ali, Nathira Abbas
Agha, Ahmad Kamal Ahmad Khidr
Twij, Wisam Abd Ali

الجامعة

جامعة بغداد

الكلية

كلية العلوم

القسم الأكاديمي

قسم الفيزياء

دولة الجامعة

العراق

الدرجة العلمية

دكتوراه

تاريخ الدرجة العلمية

2013

الملخص الإنجليزي

In this work, samples of three different types of laser dyes: Coumarin 307 (C307), Acriflavine(ACF), and Rhodamine B(RhB) have been prepared in liquid and solid phases by dissolving into different suitable solvents (ethanol, chloroform, dimethyl sulfoxide, propanol, and cyclohexane) and polymer hosts (polymethel methacrylate, PMMA, and polystyrene, PS), for a wide range of concentration ( 10-3M to 10-5M).

Their absorption and fluorescence spectra were recorded.

The fluorescence spectra have been recorded by using the constructed system.

Under high-excitation irradiance conditions to induce fluorescence, in this work a 405nm cw laser diode of 50mW was used, according to the major topic of this work (photobleaching).

The decay rate of photobleaching of Coumarin307, Acriflavine, and Rhodamine B dyes in liquid and solid phases have been studied.

In addition to this, other topics have been studied including lifetime, energy transfer, and influence of temperature and additive materials.

From the experimental results it has been found that the absorption spectra of C307 dye in used solvents show a red shift which increases with the increase of the dye concentration (reach to 5.5nm as a maximum value of C307 in chloroform, 4.5nm for ACF in DMSO, and 7nm for RhB in DMSO ) and this is attributed to solvation effects except in DMSO solvent where no shift was observed in case of C307 dye.

Inverse behavior occurred with ACF dye where no shift appeared in ethanol and propanol while red shift appeared in DMSO.

A comparison between fluorescence spectra of C307,ACF,and RhB dyes in different solvents show a blue shift reach to 50nm which increased with the decrease of the polarity of solvent.

Also a red shift appeared with the increase of the dye concentration in liquid and solid samples.

Also about 25nm blue shift was observed for solid samples compared with liquid samples for same dye.

From the photobleaching results, for one hour exposure time, it was found that solid dye samples suffered photobleaching more than the liquid dye samples.

This attributed to, in liquid solutions the dye molecules can move and circulate during the irradiation.

The percentage value of decay rate for solid samples had been recorded for one hour exposure time to the excitation source, were about 14% and 30% for 5×10-4M and record 42% and 50% for 5×10-5M for C307 and ACF dyes respectively.

For different hosts of polymer the achieved result record 60%, 14%, and 20% decay rate for one hour for C307 dye doped PMMA, PS, and PS/PMMA polymer respectively.

The lifetime for each dye in different solvents and phases have been measured in the Chemical Lab of University of Malaya.

A deconvolution process have been done to find the lifetime values at room temperature.

These values were about 5.27ns, 4.73ns and 2.74ns for C307, ACF and RhB respectively in liquid phase.

These values were reduced in solid phase for C307 was 3.71nsec.

In general the lifetime increases slightly with the increase of concentration reaching a maximum value and then decreases.

This may be attributed to the quenching caused by the formation of dimmers and aggregates at higher concentrations.

Energy transfer between ACF dye (as donor) and RhB dye (as acceptor) in ethanol and DMSO were investigated.

The energy transfer parameters have been calculated for two cases, which include: the Stern-Volmer constant, half value concentration, efficiency of energy transfer, critical transfer distance, and energy transfer rate parameter.

The achieved results indicated that the energy transfer efficiency increases with the increase of acceptor concentration to record 90.9% and 74.8% for 1×10-3M in ethanol and DMSO respectively, and that the resonance energy transfer to be the dominant mechanism in the dyes mixture.

Three additive materials, TiO2, Ag2O, and Imidazole had been mixed in appropriate ratio with dyes to increases the stability of dyes according to increase the dielectric constant of mixture, bonding between molecules, and scattered the incident excitation beam.

Finally, the influence of temperature has been studied, and it has been observed that the fluorescence intensity decreases with the increase of sample temperature and this is attributed to the increase of the radiationless processes with the increase of temperature.

Also some changes were observed of the dye structure.

In conclusion, the one of main parameters that leads to photobleaching is temperature.

التخصصات الرئيسية

الفيزياء

عدد الصفحات

133

قائمة المحتويات

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-607840