The following are excerpted from the lab manual with a couple of extra figures for your guidance.

Transcription

1 Short Lab Report Guide: The following are excerpted from the lab manual with a couple of extra figures for your guidance. ABC-UV-VIS Calculations: As indicated above in the theory section, calculate the concentrations of acetone, benzene and chloroform in the 1:100 fold diluted solution. a. using the method of selective elimination b. using the matrix inversion method ABC-UV-VIS Report: Cover Page: Put your name, partners name, experiment title and results from both analyses a and b above and the unknown letter if available. Attach: Work for the elimination method, Printouts of the Excel work and Printouts of Cary 50 Bio Spectra ABC-FTIR Report: Cover Page: Put the experiment title, your name, partner s name, the unknown letter and date on a cover page. Plot the spectra together in a stacked format: Use File Load Sample and then File Load Reference Page 1 sample on top, acetone on bottom Page 2 sample on top, benzene on bottom Page 3 sample on top, chloroform on bottom On the page with the spectra: Identify the peaks that both sample and standard have in common. Assign at least two peaks on the standard to a particular vibrational mode.

2 ABC-FTIR Report: Example of Spectra in Stacked Format with Peaks Labeled. Benzene, neat Acetone, neat Chloroform, neat Acetone Benzene Chloroform Carbonyl C=0 stretch. ABC Mixture Aliphatic C-H stretch.

3 ABC-GCMS Report: Cover page should have your name, your partner s name, the date and your unknown letter. 1. Calculate the concentrations of acetone, benzene and chloroform in the mixture using the GC peak integrals, using appropriate internal standard and standard addition formalism. Show your work. (See next page for details.) 2. Attach a chromatogram that shows all of the peaks and their integrals. 3. Attach the MS and library match for each peak in ONE of the chromatograms. 4. Indicate the likely structures for at least two ions in each mass spectrum. Fluorescence Report: Cover page should have your name, your partner s name, the date and the experiment title. 1. Experiment design. Write a sentence or short paragraph indicating the procedure you devised to produce the 1 μm rhodamine 6G. 2. Plots: (see example on next page) Plot both absorbance and fluorescence spectra on the same graph in Excel. Use the following guidelines (8 pts) a. Multiply the fluorescence spectrum values by a constant to give it roughly the same amplitude as the absorption spectrum. b. Use two different line styles, (i.e. solid and dashed) but no symbols for the plots. Use only black and white. c. No background color. d. No grid lines unless these are necessary to convey information on the plots. e. Appropriate sig-figs on axis labels. f. Use a reasonable font size and a simple font like Arial, Helvetica or Times. g. Give the graph a minimalist appearance. Use the minimum amount of ink necessary to convey the information that you want to for the graph. h. Minimize wasted space in the graph. i. Include a legend indicating which plot is fluorescence and which is emission. 3. Indicate the absorption and fluorescence emission processes using arrows of the appropriate relative lengths on a reproduction of the energy level diagram provided below. a. Label the axes on the diagram. (2 pts) b. Use arrows on the figure below to indicate: i. Initial state and final states describing the absorbance process. (2 pts) ii. Initial state and final state describing the laser excitation process. (1) iii. Initial state and final states describing the fluorescence emission process. (2 pts)

4 4. Calculate the photon energy corresponding to the peak in the absorption and emission spectra in the units specified on the report page. (see example on next page) a. Answer values correct = +2 pts b. Proper significant figures and units used = + 2 pts 5. In a paragraph or two, explain why the absorption and emission wavelengths are different and why the absorption and emission spectra look similar yet shifted on the wavelength axis. Fluorescence Experiment: Example Plot λ MAX Abs = 528 nm λ MAX Em = 548 nm Absorbance µm Rhodamine 6G in water (1.0 cm path) Emission Absorbance Wavelength (nm) Fluorescence Experiment : Example Calculations. ev := 1 nm := 10 9 m h := J s c m := s λ c := m ν := λ E:= h ν E = J Photon energy in J E mol J = mol Photon Energy in J/mol E J ev = 2.35eV Photon Energy in electron volts 1 λ 10 7 cm nm = 18939cm 1 Photon Energy in wavenumbers

5 Jablonski Diagram Page: λ MAX / nm Joules Joules / mol Electron volts (ev) Reciprocal cm (cm -1 ) S1 Absorption Emission So