1. Molecular Spectroscopy – CHEM 5591
Spring 2019
J. Mathias Weber

2. Technicalities(1) Requirements:
two semesters of undergraduate physical chemistry and graduate standing
recommended: firm grasp of algebra, complex numbers, calculus, differential equations, CHEM 5581
Class hours:
MWF 09:00 am to 09:50 am
Office Hours: Wednesday, Thursday 5 pm – 6 pm
DOES THIS WORK FOR
EVERYONE?

3. Technicalities(2) Locations: JILA tower A709 phone 492-7841
web site:
Exam schedule:
Two-hour exams: Feb 26, April 9, 6-8 pm, EKLC E1B75
Final Exam: date, time, and location TBA

4. Proposed: Thursday nights, 6 – 7 pm.
Technicalities(3)
Problem sets (homework):
usually handed out (i.e. posted on course web site) on Fridays, to be returned the following Fridays before class
homework will be graded by graduate student Wyatt Zagorec-Marks.
credits accumulated over the semester determine your homework performance grade. Everyone may drop one homework assignment without penalty.
worked solutions to problem sets will be posted on the course web page.
Travel: Due to professional travel, there will be no class meetings on Feb. 18, Feb. 20, and Feb. 22, as well as on April 1, April 3, and April 5. The missed lectures will be given on other dates instead. There may be other travel coming up.
Proposed: Thursday nights, 6 – 7 pm.

5. Technicalities(4) Grades:
homework performance: 40%
clicker questions (participation) 5%
average of the two-hour-exams: 30%
final exam: 25%
All slides and clicker questions will be posted on the course web page
Literature:
Wolfgang Demtröder “Molecular Physics” (main text book for the course).
Wolfgang Demtröder “Laser Spectroscopy” (useful resource)
H. Haken, H. C. Wolf “Molecular Physics and Elements of Quantum Chemistry” (useful resource)
G. Herzberg “Molecular Spectra & Molecular Structure” (the spectroscopy “bible”)
Browse the library or the book store for other books that you may like...

6. Tentative List of Topics
Classical treatment of interaction of light and matter
Transitions between states - Einstein coefficients
Line shapes
States and Spectra of the H-Atom
States and Spectra of Multielectron Atoms
Orbit and Spin Magnetism, Spin-Orbit Interaction, Fine Structure
The Born-Oppenheimer Approximation
Purely Rotational Spectra of Diatomic Molecules
Ro-vibrational Spectra of Diatomic Molecules
Electronic States of Diatomic Molecules
Electronic Spectra of Diatomic Molecules
Multiphoton transitions
Raman Spectroscopy
Nuclear Spin Statistics
Group Theory
Rotations of Polyatomic Molecules
Vibrations of Polyatomic Molecules – Normal Modes
Electronic States of Polyatomic Molecules
Spectra of Polyatomic Molecules
Spectra of Nanomaterials
Semiclassical description of an absorption process
Lasers

7. Goals of Spectroscopy:
Experimental determination of the properties of the quantum states of a system (atoms/molecules/materials).
Theoretical prediction of these properties.
Study of transition probabilities between these states
Understanding of dynamics and processes (e.g. dissociation, radiationless transitions, excited state lifetimes, electron emission, ...)

8. Approaches: How do we get such data? Interaction of a sample with
Light:
absorption
emission
scattering
Matter particles
electrons
neutrons
atoms
molecules
...

9. Method
typical spectral range
degree of freedom
NMR
107 – 109 Hz
3·10-4 – 3·10-2 cm-1
nuclear spin
EPR
109 – 1011 Hz
3·10-2 – 3 cm-1
electron spin
microwave spectroscopy
109 – 1012 Hz
3·10-2 – 30 cm-1
mol. rotation
infrared spectroscopy
1012 – 1014 Hz
30 – 3·103 cm-1
mol. vibrations
UV/vis spectroscopy
1014 – 1016 Hz
3·103 – 3·105 cm-1
valence electrons
X-ray spectroscopy
> 1016 Hz
> 3·105 cm-1
core electrons

10. Typical energies: ionization potentials 5 – 15 eV (40 – 121·103 cm-1)
electron affinities 0 – 4 eV (0 – 32·103 cm-1)
dissociation energies 1 – 5 eV (0 – 40·103 cm-1)
vibrations (fundamental) eV (80 – 4000 cm-1)
rotations < 1 meV (0.008 – 8 cm-1)
Outlier: H2 (Be = cm-1; e = cm-1)

11. The color of a nonfluorescent object is due to the light left
after absorption

12. The color of a nonfluorescent object is due to the light left
after absorption
absorbed
perceived
perceived
absorbed
absorbed
perceived