
Spectroscopic Simulator
This applet covers an aspect of the Physical Chemistry II course that students
often find confusing. Although it is based on relatively simple mathematics, a
complete understanding of the phenomenon requires assimilating the following
concepts:
 The energy levels of a diatomic molecule are given by the formula:
 E(v,J) = hv (v + ½) + BJ (J + 1); v = 0..infinity, J=0..infinity
 A molecule absorbs light at frequencies that correspond to difference
between energy levels. In this case, we are interested in the following
differences, frequency of light:
 E (v = 1, J')  E (v = 0, J); with J' = J + 1 or J 1
 The intensity of the transition is proportional to the population of the
lower state, intensity is proportional to:
 J (J + 1) exp[E (v = 0, J) / kT]
Many students are comfortable with these separate concepts,
but find it difficult to combine them together to produce an
understanding of rovibrational spectroscopy. This applet simulates an
infrared spectrometer, allowing students to adjust the experimental and
molecular parameters and observe the effects on the infrared spectrum. Students
may use the applet to first focus on each of the individual concepts, within
the context of the actual experiment, and then to integrate these concepts
into a coherent whole.
Run the applet >>
