In an Experiment to Investigate the Decay of Photoexcited Tryptophan

question 20

Multiple Choice

In an experiment to investigate the decay of photoexcited tryptophan, the observed lifetime of the excited state was measured for various concentrations of oxygen, O₂, which acted as a quencher. By constructing a Stern-Volmer plot of the following data, determine the rate constant for fluorescence quenching.
$\begin{array}{llllll}{\left[\mathrm{O}_{2}\right] / \mathrm{mol} \mathrm{dm}^{-3}} & 0.02 & 0.04 & 0.06 & 0.08 & 0.10 \\\tau_{\text {pbs }}\left(\mathrm{O}_{2}\right) / \mathrm{ns} & 1.64 & 1.18 & 0.91 & 0.74 & 0.63\end{array}$

• A) 12.3 ? 10^-9 mol^-1 dm³ s^-1
• B) 2.7 ? 10^-9 mol^-1 dm³ s^-1
• C) 15.9 ? 10^-9 mol^-1 dm³ s^-1
• D) 10.7 ? 10^-9 mol^-1 dm³ s^-1

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