Advanced Molecular
Spectroscopy – CHEM 5591
Spring 2014
J. Mathias Weber
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:
M, T: 4 pm – 5 pm
DOES THIS WORK FOR EVERYONE ?
Technicalities(2)
• Locations:
– JILA tower A709
– phone 492-7841
– email weberjm@jila.colorado.edu
– web site:
http://jila.colorado.edu/weberlabs/course-CHEM5591.html
• Exam schedule:
– Two-hour exams: Feb 18, April 1
6-8 pm, locations TBA
– Final Exam: date, time, and location TBA
DOES THIS WORK
FOR EVERYONE ?
Technicalities(3)
• Problem sets (homework):
– usually handed out (i.e. posted on course web site) on Wednesdays, to
be returned the following Wednesdays before class
– homework will be graded by graduate student Ben Knurr.
– 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. 26,
Feb. 28, April 28, April 30 and May 2. The lectures will be given on other
dates instead. I will set up a doodle poll to find an appropriate day in the
week. It may have to be Saturday afternoons ….
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...
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 dynamic problems (e.g. dissociation,
radiationless transitions, excited state lifetimes,
electron emission, ...)
Approaches:
How do we get such data? Interaction of a sample with
• Light:
o absorption
o emission
o scattering
• Matter particles
o electrons
o neutrons
o atoms
o molecules
o ...
Method
typical spectral range
degree of freedom
NMR
107 – 109 Hz
nuclear spin
3·10-4 – 3·10-2 cm-1
EPR
109 – 1011 Hz
electron spin
3·10-2 – 3 cm-1
microwave spectroscopy
109 – 1011 Hz
mol. rotation
3·10-2 – 3 cm-1
infrared spectroscopy
1011 – 1014 Hz
mol. vibrations
3 – 3·103 cm-1
UV/vis spectroscopy
1014 – 1016 Hz
valence electrons
3·103 – 3·105 cm-1
X-ray spectroscopy
> 1016 Hz
> 3·105 cm-1
core electrons
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 – 32·103 cm-1)
• vibrations
0.1 - 0.5 eV
(800 – 4000 cm-1)
• rotations
10 meV – 1 meV (0.08 – 8 cm-1)
The color of a nonfluorescent object is due to the light left
after absorption
0.6
0.5
Na2Cr2O7
K2IrBr6
0.3
0.2
0.4
Cu(NO3)2
absorbance
absorbance
0.4
absorbance
0.15
0.2
0.10
0.05
0.1
0.0
300
0.0
400
500
600
wavelength [nm]
700
800
300
0.00
400
500
600
wavelength [nm]
700
800
300
400
500
600
wavelength [nm]
700
800
The color of a nonfluorescent object is due to the light left
after absorption
0.6
0.5
Na2Cr2O7
K2IrBr6
0.3
0.2
Cu(NO3)2
0.4
absorbance
absorbance
0.4
absorbance
0.15
0.2
0.10
0.05
0.1
0.0
300
0.0
400
500
600
700
800
400
500
600
700
800
wavelength [nm]
wavelength [nm]
perceived
absorbed
300
0.00
300
400
500
600
700
wavelength [nm]
absorbed
perceived
absorbed
perceived
800