Experimental stages

First meeting

Things to read before the lab:

1. Molecular spectroscopy – electronic transitions, selection rules, transition intensity, Frank-Condon coefficients, relaxation processes in excited molecules (radiative and non-radiative).
2. Electronic levels of aromatic molecules and how solvent polarity affects  transitions.
3. Absorption spectra, Beer-Lambert law.
4. Fluorescence spectra, usage of reference (QBS), quantum yield, polarity corrections to quantum yield.
5. Polarity scale – E_T(30)

Things you would perform:

1. Preparation of solutions
2. Measurements of absorption spectra – absorption peek wavelength and optical density (OD) at 360 nm.
3. Measurement of fluorescence spectra

At this stage, the students would be able and required to calculate the quantum yield of the Bimane molecule.

Second meeting       

Things to read before the lab:

Single photon counting technique – basics and the role of various components in the experimental setup, the pile-up problem

 Things you would perform:

1. Application of the single photon counting technique to measure the convolution of the experimental setup with the decay signal of the excited Bimane molecules.
2. Calibration of the time in the experiment and measurement of the bear response of the experimental setup.

At this stage, the students would be able and required to find the scaling constant for converting between A/D channels and real physical time.

Third Meeting

Things to read before the lab:

Methods of deconvolution

 Things you would perform:

Use software to analyze of the SPC experiments data – deconvolution and extraction of total life times of the excited Bimane molecules in the various solvents.

Final report

1. Theoretical background.
2. Description of all experimental methods and problems.
3. Analysis of the results to obtain plots of k_rad, absorption energy maxima and fluorescence energy maxima as a function of solvent polarity.
4. Discuss the implication of your results to understanding of molecular conformation in polar and apolar solutions.  Compare your results to the literature.