Hartley bands

We have investigated the two principal channels in the dissociation of ozone at wavelengths corresponding to the Hartley band ... 

Table 5. The branching ratios into the three spin-orbit states of the oxygen atom fragment as a function of photolysis wavelength in the Hartley band. Note that a statistical yield would give a branching ratio of 5 3 1, or as percentages, 55.5 33.3 11.1.

This channel has recently been observed in the 335-352 nm region of the Huggins band.49 Such a channel is not inconsistent with previously determined branching ratios in the Hartley band. These determinations typically rely on measuring the amount of 0(3P) as a function of time and inferring the channels present from the observed kinetics. Such a measurement accounts for the amount of 0(4D) versus 0(3P) formed but not which channels gives rise to these species. 

Absorption spectra of 03 are shown in Figs. 4.7 and 4.8. The strongest absorption, in the 200- to 300-nm region, is known as the Hartley bands. It is this absorption that is responsible for the so-called actinic cutoff ... 

The Huggins bands are in the 300- to 360-nrn region, whereas the 440- to 850-nrn region represents the Chappuis bands. As seen in Figs. 4.7 and 4.8, both absorptions are much weaker than the Hartley bands. 

The Hartley band of ozone has been the object of systematic investigations. The vibrational structures on top of the band have motivated studies of the dissociation dynamics on the corresponding potential surface [107]. 

In a more recent work, Joens [158] has assigned the structures of the Hartley band using a Dunham expansion, that is equilibrium point quantization. The lifetime predicted by his analysis is extremely short, equal to 3.2 fs, while the symmetric stretching period is of 30 fs. Recall, however, that the interpretations in terms of equilibrium point expansions and in terms of periodic orbits are strictly complementary only for regular regimes. 

The interpretation of a spectrum from a dynamical point of view can also be applied to a spectrum containing a broad feature associated with direct and/or indirect dissociation reactions. From such spectra dynamics of a dissociating molecule can also be extracted via the Fourier transform of a spectrum. An application of the Fourier transform to the Hartley band of ozone by Johnson and Kinsey [3] demonstrated that a small oscillatory modulation built on a broad absorption feature contains information of the classical trajectories of the vibrational motion on PES, so-called unstable periodic orbits, at the transition state of a unimolecular dissociation. 

Photochemical Production. The direct production of Oil1 A) from the ground state by light absorption is not possible since the transition is highly forbidden. However, 02( A) is a primary product of the photolysis of 03 in the Hartley band (see Section VI-11)... 

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