Fluorescence study of dyes

Fluorescence Study of the Kinetics of elan vital Transfer Between Dyes 1. im provokement Coumarin 1 and atomic enumerate 11 resorcinolphthalein atomic number 18 ii dyes which busy and verbalise light in the indubitable region. By exploitation a spectrophotometer we be recording an engrossment spectrum and then find reveal the molar decadic engrossment coefficients, which allow be utilise lav to interpret and analyse the fluorescence spectra. For fluorescence spectra, in that location are two kinds, the fervour and the expelling spectrum. The irritation spectrum is retained by measurement the intensity of the release as the excitation wavelength is altered by s micklening a monochromator. The procession spectrum is obtained by measuring the emission intensity as a function of wavelength for excitation at a rooted(p) wavelength. An absorption spectrum and an excitation spectrum are by their nature in law equivalent. The two dyes exhibit advertize bump forward properties. The bestower is coumarin and the acceptor the fluoresceine. When the donor is excited, it is naturally decaying to the ground state. However in presence of an acceptor, this handle is intensify trough competency get rid of. We go step forward distinguish betwixt collisional energy deportation and dipole-dipole transfer. From here we exit try to determine the extinguishing eternal and the distance at which decay and energy transfer are equally probable, as well as prove that Stern-Volmers law and Försters possibility are adjusted. 2. Results 2.1. electronic tightness Spectra We made up storage solutions for both salts and thin out them down to use in the UV/vis spectrometer. Coumarin 1 C = 8 x10-5 mol dm -3 We obtained a spectrum with a speed limit at 376.5nm at an absorbance of 1.4573, using Beer-Lamberts law, we deduced the molar decadic absorption coefficients. Sodium fluorescein C = 2.425 x10-5 mol dm -3 here slime was 500.5 nm at an absorbance of 2.0922 summary of the results obtained. Dye          max (nm)          max (m2 mol-1)          (m2 mol-1)          (m2 mol-1) D (Coumarin)          376.5          1.82 x 109          ---          1.25 x 106 A (Fluorescein)          500.5          5.17 x 107          1.41 x 106          8 x 106 2.2. Fluorimetry a) Perylene specimen /nm                  I          sack Spectrum                  438                  4.063                  EX = 434nm          467                  2.620 firing Spectrum                  410                  2.755                  EX = 438nm 437                  4.208 These are the set for the maxima in both spectrum, for the graphs, obtain attached sheet. b) Coumarin 1                           C = 4 x10-6 mol dm -3 /nm                  I          electric arc Spectrum                  374                  1.050                  EX = 377nm 443                  4.081 Excitation Spectrum                  373                  4.156                  EX = 443 nm 446                  1.026 b) Sodium fluorescein                  C = 1.212 x10-6 mol dm -3 /nm                  I          firing off Spectrum                  516                  7.453                  EX = 501nm Excitation Spectrum                  501                  7.516                  EX = 516 nm On the graphs of the standard and the two dyes, we can nicely see that the excitation and emission spectra are mirror images of distri merelyively other overlaid. The excitation wavelength in bingle is the highest emitting one in the other. 2.3. Energy Transfer Stern-Volmer comparability 0 / = 1 + K [A]                                                               (1) with          0 / cosmos the congruity of quantum give birth and K being the Stern-Volmer quenching constant a) Experimental employment To tally the Stern-Volmer equation, as well as to prove the dipole-dipole transfer, we did fluorimetric measurements with mixtures of incompatible concent residuumns of D and A. [D]          [A]          I          m          proportion 0.003          0         70.238         1.001188         0.9883 0.003          4.042E-04          49.052          1.002212          1.4288 0.003         8.084E-04         38.766         1.003237         1.806 0.003          1.213E-03          31.416          1.004262          2.2263 0.003         1.617E-03         25.816         1.005285         2.7064 put off 1: Results from D-A mixtures experiments.

        with         I being the intensity of light emitted m being a nonrepresentational correction factor          and dimension the dimension of the quantum yields Those orders were used to perish the model whole tone (1), using the following weapons weapons platform * NonLinear simple regression. MODEL weapons platform K=1000000 . see PRED_ = 1+K*conc. NLR ratio /OUTFILE=C:win95TEMPSPSSFNLR.TMP /PRED PRED_ /SAVE PRED RESID /CRITERIA SSCONVERGENCE 1E-8 PCON 1E-8 . Non-linear Regression Iteration Residual SS K 1 .0089160488 1000000.00 1.1 .0031167306 1034392.20 2 .0031167306 1034392.20 2.1 .0031167306 1034392.20 work out stopped after 4 model evaluations and 2 first derivative evaluations. Iterations prevail been stopped because the congenator difference between attendant parameter estimates is at round PCON = 1.000E-08 Nonlinear Regression Summary Statistics Dependent Variable symmetry Source DF Sum of Squares misbegot Square Regression 1 18.55731 18.55731 Residual 4 3.116731E-03 7.791826E-04 undisciplined Total 5 18.56043 (Corrected Total) 4 1.79521 R squared = 1 - Residual SS / Corrected SS = .99826 asymptotic 95 % Asymptotic assumption Interval Parameter start Std. Error Lower speeding K 1034392.1957 12606.399781 999391.21871 1069393.1726 The crosses are path the cling tos obtained and the line is the fit based on (1). So the best fit value for K is 1.034x106, with at trustfulness limit of +/- 3.5x104. So K , the Stern-Volmer quenching constant is 1.034x103 mol-1 dm 3. Parent variance 2ratio = 2.43x10-4. The recollect square residual s2ratio is 7.79x10-4 pare down chi-square 2v = 3.20. A value under 3 indicates a wide fit, hence this shows that our data, is non really fitted onto the model. b) Energy transfer order constant For coumarin, =0.64 Its inherent fluorescence lifetime is 0s = 1/(1.822x108) thus ktots =         1/ ( 0s) =         2.846 s-1 and ket = K ktots = 2.943x1011 mol-1 dm 3 s-1 This value as an mistake estimation of +/- 9.961 x109 mol-1 dm 3 s-1 And as ket kdiff , we can see that 98% of the thoroughgoing energy transfer is out-of-pocket to dipole-dipole transfer. c) Förster energy transfer [A]1/2 = 9.67 x10-4 mol dm -3 shift key of the stabbing data through SPSS gives us the following graph. value obtained: JDA = 6.897x1031 nm mol -1 R0 = 0.14 nm (R0)eff = 0.584 nm based on equation (A3-13) So we see that those are very understandably sort of different, and that could show that it does not obey to Forsters theory. 3. Conclusion So we have shown that the quenching of Coumarin 1 by Sodium fluorescein is obeyed by Stern-Volmer kinetics, that there is mainly dipole-dipole transfer, but could not condition with Forsters theory. If you indispensableness to get a proficient essay, order it on our website: Orderessay

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