Absorption and Laser Induced Fluorescence Spectra of Molecular Iodine

In this experiment you will determine the energy levels of a diatomic molecule.

Questions

Answer in writing:

  1. For the absorbance spectroscopy and LIF parts of the experiment, write in detail:
    1. Subject
    2. Purpose
    3. List the equations you will use. Explain the meaning of each variable and its units.
    4. List the known values needed for the experiment (e.g., for the calibration you will need the peak wavelengths of mercury).
    5. List the literature values of the quantities you will be measuring in this experiment.
  2. Explain how the detector you will use works. Specifically:
    1. Monochromator: What happens when light passes through the monochromator? Explain in terms of diffraction (עקיפה) and interference (התאבכות).
    2. Photomultiplier: Is there a minimal intensity required in order to get signal amplification? Can you get a signal for each photon?
  3. Explain some of the principles behind the equipment you will use:
    1. Exlpain spontaneous emission, stimulated emission and absorption.
    2. How does a laser work? What is the main difference between laser light and the light of a mercury lamp?
    3. What is the Franck-Condon principle?

Prepare in advance and bring to the lab:

  1. Values of ωe, ωeχe, De, D0, E*, Be and re for iodine molecule obtained from literature.
  2. The wavelength of the five major peaks of a mercury lamp.
  3. Use equation 23 and calculate the resolution of a monochromator with a reciprocal linear dispersion of 1.6 nm/mm (for a 1200 grooves/mm grating) and w=500μm wide entrance slit. Considering this resolution, what features will be seprable in the spectrum?