VIII - Energy states of molecules

Abstract

Examines the spectral patterns corresponding to rotational, vibrational, and electronic energy levels, and the relationship that can be established between these observed patterns and the parameters of the molecular model.

Laser-induced molecular fluorescence: A physical chemistry experiment

“…The Franck-Condon Principle A typical low-resolution spectrum is illustrated in Figure 2. The intensity pattern of the peaks nicely illustrates the quantum-mechanical Franck-Condon principle (2,15). For comparison we show in Figure 3 recently calculated Franck-Condon factors (FCFs) for this fluorescence series (16), plotted as a function of v".…”

“…The notation employed in this paper is standard spectroscopic usage, as summarized in the article by Hollenberg (2). 2 Complete potential curves for the B and X states have been illustrated previously by Stafford (/). dental in nature, as it results from the circumstantial occurrence of an I2 absorption transition at the same frequency as the radiation produced by the laser.…”

“…In the I2 absorption experiment the student is introduced to electronic spectroscopy through an analysis of the vibrational structure in the 63110+0 -X]2g+ electronic transition (1)(2)(3)(4)(5). Ordinarily the complex rotational fine structure within each u'-v" vibrational band is not resolved, so students measure and assign just the sharp heads of the red-degraded bands.…”

The DCl-HBr isotope exchange equilibrium. A statistical and experimental exercise for the physical chemistry laboratory

“…(6) as AE"(erg/mole) = 7V/ic[jD"'(DCl) -D"(HC1)Il-Dij'(DBr) -£WHBr)|] (7) or (2irmikTfnNkT 8ir2LkT 1 qf = -------;- where m is the mass of molecule, a is the symmetry term, I is the moment of inertia, tq0 is the fundamental frequency of vibration, and the other constants have their usual significance. The moments of inertia, fundamental frequencies, and dissociation energies can in principle be obtained by the methods described by Stafford (4) and summarized by Hollenberg (5), and in this sense this experiment can be regarded as an extension of the experiments they describe. However, there are practical difficulties in obtaining good fundamental and overtone spectra 1 To whom correspondence should be addressed.…”

Introducing Students to a Synthetic and Spectroscopic Study of the Free Radical Chlorine Dioxide

“…For example, the classic undergraduate physical chemistry laboratory exercise involving the absorption and emission spectra of diatomic iodine (I 2 ) is very popular. This popularity is largely due to the opportunity that students have to conceptually visualize molecular energy levels and directly determine molecular constants in the laboratory setting, , and several variations of this lab have also been introduced. − The laboratory exercise outlined here is similar in spirit to the classic iodine lab and centers around the study of the free radical chlorine dioxide (ClO 2 ). ClO 2 has received a considerable amount of attention for its ability to purify drinking water without creating harmful concentrations of disinfection byproducts, , its strong antimicrobial properties, and its ability to oxidize atmospheric ozone .…”