Physical Chemistry , 1st ed.

operator are usually given in the character table, as discussed in the previous chapter regarding allowed vibrational transition ...

c.All of the atoms in chloroform have complete valence shells and all-paired electrons. This suggests a colorless compound. It i ...

implies four molecular orbitals, each with its own characteristic values for c 1 , c 2 ,c 3 , and c 4 , and each with its own en ...

molecule is the HOMO →LUMO transition, which may or may not be an allowed transition. (It usually is, so the HOMO and LUMO are i ...

for can be determined from atomic spectra. Since a specific value for is not necessary in understanding the patternof the ele ...

as opposed to the nonaromatic aliphatic hydrocarbons. The Hückel approxi- mation provides some clues for benzene’s distinctions. ...

benzene. This generality is called the 4n 2 rule,where nis any nonnegative integer and the expression 4n 2 yields the number of ...

is usually converted into vibrational energy. Such a process is called an inter- nal conversion,because the electronic state cha ...

but the timescale is much faster than the normal human perception. Phosphorescence, in terms of our own physical perception, is ...

right frequency. It is dependent on the concentration of species in the ex- cited state but independentof the photon density ( ...

and the only varying factor in this ratio is , the frequency of the transition. What this ratio says is that the greater the fr ...

a billion billion times more likely for light having wavelength of 300.0 nm than a wavelength of 21.0 cm. Before we get to laser ...

of photons, all having the same wavelength (and phase, as it turns out), occurs. Because all of these photons have the same wave ...

short order and a pulse of lasing action occurs at a wavelength of 694.3 nm, which is in the red region of the spectrum. Typical ...

energy level diagram for this laser is shown in Figure 15.33, with Figure 15.34 showing an example of a He-Ne laser in operation ...

forbidden transitions. For molecules, there is a convention based on the char- acter table for the symmetry point group, but wid ...

15.2 Selection Rules 15.1.Linearly polarized light can be assigned a specific irre- ducible representation of a symmetry point g ...

15.7 & 15.8 Franck-Condon Principle and Polyatomic Molecules 15.24.Figure 15.36 shows two vibronic levels of a molecule. Ind ...

16 W E HAVE MADE PASSING MENTION of the effects of magnetic fields on atomic or molecular energy levels. For example, we have st ...

troscopy. In MR spectroscopy, an experimenter has the opportunity to vary both the electromagnetic radiation and the magnetic fi ...