In the fluorescence quenching of rhodamineB dye, the fluorescence decay of rhodamineB in the DMF-solution with ethanol-watermixture was monitored by measuring the605 nm emission lifetime (decay of intensityover time) after a laser pulse. The lifetime (t)of rhodamine B in absence of quenchers is Do2.10 ns. Quenching of rhodaminefluorescence by the presence of 2% ethanol-water mixture reduced the lifetime (T) to 1.86ns. Using the following Stern-Volmerequation, what would be the rhodamine Bemission lifetime in ns by changing theethanol-water to 13 %? (Final answer shouldbe of three significant figures)1.142ToT=k₁ + k₂+k₂ [Q]k₁ + k₁₂

To determine the fluorescence lifetime of rhodamine B when the concentration of the ethanol-water…

Answered: In the fluorescence quenching of…

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

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Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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In a photochemical experiment it is observed that 5.78×10-5 mol of uranyl oxalate is decomposed at a wavelength of 300 nm emitted by a lamp in one hour. When acetone was irradiated with the same lamp for 10 hours, the amount of acetone decomposed was found to be 2.32× 10-4 mol. What is quantumyield for the acetone decomposition under the same condition?
The chemical shift of the CH3 protons in acetaldehyde (ethanal) is δ = 2.20 and that of the CHO proton is 9.80. What is the difference in local magnetic field between the two regions of the molecule when the applied field is (a) 1.2 T, (b) 5.0 T?
d) Doppler broadening is a source of line broadening in the flame of an atomic absorption instrument, λ = 20 (7x10-7)(0.5. Find the Doppler line width for the absorption line λ = 248.3 nm of Fe in a 2500 K flame (T), where M is the mass of the atom (56 Da).
A 0.00002415 mol dm-3 solution of a substance had an absorbance of 0.325 in a 0.5 cm path length cell. Calculate the molar absorption coefficient for the substance
Suppose you measure the absorbance of a yellow dye solution in a 1.00 cm cuvette (b=1.00 cm). The absorbance of the solution at 427 nm is 0.84 . If the molar extinction coefficient of yellow dye at 427 nm is 27400 M–1cm–1, what is the concentration of the solution in M?
What are the differences between atomic and molecuar absorption spectroscopies?
In a mass spectrometer, two beams of singly ionized isotopes of uranium 23592U and 23892U are injected with velocity 1.4*105m/s into a magnetic field of strength 0.7 T normally. Compute the distance d between the two trace lines of the isotopes after they complete one semi-circle. (Given: masses of the isotopes are m235 = 3.9*10-25 kg and m238 = 3.95*10-25) a) 1.26 cm b) 0.63 cm c) 0.32 cm d) none of these.
5. (a) The Mossbauer effect depends upon the recoilless emission of a y-ray. How important is it to embed the emitter nucleus in a bulky and rigid crystal lattice? (b) Briefly describe the isomer shift in Mossbauer spectroscopy.
(c) Comment on the truth, or otherwise, of the following statement. "Fast time-scale flash photolysis can be used to determine rate constants for collisional relaxation (quenching) processes of singlet and triplet states. Radiative decay rate constants (Einstein A coefficients) can be determined from such measurements, and can also be calculated from absorption coefficients."
The fluorescence lifetime of a compound is 10 ns and a quantum yield of 10% was measured. Calculate the kF value. Show your work.
The quantum yield of light-induced chemical reactions (called photochemical reactions) measures the efficiency of the process. The quantum yield, ϕ, is defined as:ϕ=numberofreactioneventsnumberofphotonsabsorbed . Suppose a quantum yield for the reaction CH3X→CH3+Xis ϕ= 0.95. A cuvette containing a solution of CH3Xis irradiated with 280-nmwith a power of 885 mWfor 10.0 minutes. Part A Assuming total absorption of the light by the sample, what is the maximum amount (in moles) of CH3Xthat breaks apart?Express your answer to two significant figures. nothingmolCH3Xm o l C H 3 X actual
Iron(III) forms a complex with thiocyanate ion that has the formula Fe(SCN)+2. The complex has an absorption maximum at 580nm. A sample of well water was assayed according to the following scheme: Sample Sample Vol (mL) Oxidizer Fe(ii) (mL) added 2.75ppm KSCN (0.050 M) H20 (mL) Abs @ 580 nm 1 50.00 5.00 5.00 20.00 20.00 .549 2 50.00 5.00 0 20.00 25.00 .231 What is the concentration of Fe in the well water sample?

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