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CHEM106: Physical Chemistry II

Unit 8: Spectroscopy II: Electronic Transitions   The previous unit dealt with IR causing rotational and vibrational phenomena within a molecule.  In this unit, you will learn what happens when a more energetic radiation, such as ultraviolet or visible (UV-Vis) light interact with molecules.  UV-Vis light possesses sufficient energy to cause electronic transition.  During an electronic transition, electrons jump from their (low-energy) ground state configuration into a high-energy excited state.  The excited electrons then find their way back to the ground state, and here some interesting phenomena might occur, such as fluorescence and phosphorescence.  Some direct applications of electronic transitions include LASERs.

Unit 8 Time Advisory
This unit will take you 9 hours to complete.

☐    Subunit 8.1: 6 hours

☐    Subunit 8.2: 3 hours

Unit8 Learning Outcomes
Upon successful completion of this unit, the student will be able to: - Describe electronic transitions. - Compare absorption and emission spectra. - Describe the excited state of molecules. - Explain the difference between fluorescence and phosphorescence. - Describe the Frank-Condon Principle. - Describe the principles of operation of lasers.

8.1 Electronic Spectroscopy of Molecules   - Reading: The Chemical Educator, Vol. 12, No. 4: David P. Richardson and Raymond Chang’s “Lecture Demonstrations of Fluorescence and Phosphorescence” Link: The Chemical Educator, Vol. 12, No. 4: David P. Richardson and Raymond Chang’s “Lecture Demonstrations of Fluorescence and Phosphorescence” (HTML)
 
Instructions: Read this article in The Chemical Educator for an interesting explanation of the difference between fluorescence and phosphorescence. From the link above, click on the image of the PDF version under "Full Text" on the right side of the page. Note that this reading also covers the material you need to know for subunits 8.1.1–8.1.6.

 Studying this resource should take approximately 1.5 hours.    

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.
  • Reading: Concordia College: Professor Darin J. Ulness’s “Molecules and Molecular Spectroscopy” Link: Concordia College: Professor Darin J. Ulness’s “Molecules and Molecular Spectroscopy” (PDF)
     
    Instructions: Please click on the link and select the “Old Course Notes” hyperlink to download the PDF file.  Read pages 253–259.  Studying this resource should take approximately 4.5 hours to complete.  Note that this reading also covers the material you need to know for subunits 8.1.1–8.1.6.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above. 

8.1.1 The Structure of the Electronic State   Note: Subunits 8.1.1–8.1.6 are covered by the readings assigned beneath subunit  8.1., which is mainly based on the readings from  Professor Darin J. Ulness’s “Molecules and Molecular Spectroscopy,” section 17.4.  In particular, please focus on David P. Richardson and Raymond Chang’s “Lecture Demonstrations of Fluorescence and Phosphorescence” to learn about the difference between fluorescence and phosphorescence.

8.1.2 Absorption Spectra   Note: Subunits 8.1.1–8.1.6 are covered by the readings assigned beneath subunit  8.1., which is mainly based on the readings from  Professor Darin J. Ulness’s “Molecules and Molecular Spectroscopy,” section 17.4.  In particular, please focus on David P. Richardson and Raymond Chang’s “Lecture Demonstrations of Fluorescence and Phosphorescence” to learn about the difference between fluorescence and phosphorescence.

8.1.3 Emission Spectra   Note: Subunits 8.1.1–8.1.6 are covered by the readings assigned beneath subunit  8.1., which is mainly based on the readings from  Professor Darin J. Ulness’s “Molecules and Molecular Spectroscopy,” section 17.4.  In particular, please focus on David P. Richardson and Raymond Chang’s “Lecture Demonstrations of Fluorescence and Phosphorescence” to learn about the difference between fluorescence and phosphorescence.

8.1.4 Fluorescence and Phosphorescence Spectra   Note: Subunits 8.1.1–8.1.6 are covered by the readings assigned beneath subunit  8.1., which is mainly based on the readings from  Professor Darin J. Ulness’s “Molecules and Molecular Spectroscopy,” section 17.4.  In particular, please focus on David P. Richardson and Raymond Chang’s “Lecture Demonstrations of Fluorescence and Phosphorescence” to learn about the difference between fluorescence and phosphorescence.

8.1.5 Franck-Condon Activity   Note: Subunits 8.1.1–8.1.6 are covered by the readings assigned beneath subunit  8.1., which is mainly based on the readings from  Professor Darin J. Ulness’s “Molecules and Molecular Spectroscopy,” section 17.4.  In particular, please focus on David P. Richardson and Raymond Chang’s “Lecture Demonstrations of Fluorescence and Phosphorescence” to learn about the difference between fluorescence and phosphorescence.

8.1.6 The Franck-Condon Principle   Note: Subunits 8.1.1–8.1.6 are covered by the readings assigned beneath subunit  8.1., which is mainly based on the readings from  Professor Darin J. Ulness’s “Molecules and Molecular Spectroscopy,” section 17.4.  In particular, please focus on David P. Richardson and Raymond Chang’s “Lecture Demonstrations of Fluorescence and Phosphorescence” to learn about the difference between fluorescence and phosphorescence.

8.2 Lasers and Applications   - Reading: Concordia College: Professor Darin J. Ulness’s “Lasers” Link: Concordia College: Professor Darin J. Ulness’s “Lasers” (PDF)

 Instructions: For Professor Ulness’s notes, please click on the
link above, and select the “*Old Course Notes*” hyperlink to
download the PDF file.  Read pages 260–266.  Studying this resource
should take approximately 3 hours to complete.  Note that this
resource also covers the material you need to know for subunits
8.2.1–8.2.5.  
    
 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.

8.2.1 Anatomy of the Laser   Note: Subunits 8.2.1–8.2.5 are covered by the readings assigned beneath subunit  8.2., which is mainly based on the readings from  Professor Darin J. Ulness’s “Molecules and Molecular Spectroscopy,” Chapter 18.

8.2.2 Physics of Laser Operation   Note: Subunits 8.2.1–8.2.5 are covered by the readings assigned beneath subunit  8.2., which is mainly based on the readings from  Professor Darin J. Ulness’s “Molecules and Molecular Spectroscopy,” Chapter 18.

8.2.3 Population Inversion   Note: Subunits 8.2.1–8.2.5 are covered by the readings assigned beneath subunit  8.2., which is mainly based on the readings from  Professor Darin J. Ulness’s “Molecules and Molecular Spectroscopy,” Chapter 18.

8.2.4 Stimulated Emission   Note: Subunits 8.2.1–8.2.5 are covered by the readings assigned beneath subunit  8.2., which is mainly based on the readings from  Professor Darin J. Ulness’s “Molecules and Molecular Spectroscopy,” Chapter 18.

8.2.5 Applications of Lasers   Note: Subunits 8.2.1–8.2.5 are covered by the readings assigned beneath subunit  8.2., which is mainly based on the readings from  Professor Darin J. Ulness’s “Molecules and Molecular Spectroscopy,” Chapter 18.

  • Assessment: The Saylor Foundation’s “Assessment 12” Link: The Saylor Foundation’s “Assessment 12” (DOC)
     
    Instructions: Complete the attached assessment questions to check your understanding of the material covered thus far. Once you have completed the assessment, you may check your answers against the “Answer Key” (DOC).
     
    Completing this assessment should take approximately 1 hour.