Photo-ionization energy

Fig. 5 Photo-ionization energies of the OSO4 molecule from experiment, from V-Xa calculations and Hartree Fock-Configuration Interaction (HF-CI) calculations.

The excited ions (DH +, DX ) and/or radicals (D ) might either go back to the original dye molecule, or undergo further reactions with other components in water such as dissolved oxygen, free H70H, and other impurities to form colourless end products. The presence of water was used to carry the charged intermediates, which lowered the photo-ionization energy, and therefore facilitated the dye decomposition. 

One hydrophilic anthraquinone dye (Al) and one hydrophobic anthraquinone dye (A2) were selected to explore the effect of solubility to the UV-irradiation. From the experimental data, the hydrophilic anthraquinone dye (sulphonate anthraquinone reactive dye) has about twice the dye removal rate than hydrophobic anthraquinone dyes at high pH. Since all the anthraquinone dyes have similar chemical structures and the pH did not show any distinguish effect in dye removal for A2, it is obvious that the rate difference is mainly due to the difference of solubility. The effect of dye s solubility to the photodegradation may be interpreted by the photo-ionization mechanisms proposed by Leaver I.H. (1980). The water can carry the charged intermediates (Al only), which lower the photo-ionization energy and therefore facilitate the dye degradation. 

Jorgensen CK (1975) Partly Filled Shells Constituting Anti-bonding Orbitals with Higher Ionization Energy than Their Bonding Counterparts. 22 49-81 Jorgensen CK (1975) Photo-Electron Spectra of Non-Metallic Solids and Consequences for Quantum Chemistry. 24 1-58... 

IP Ionization potential is the amount of energy needed to remove an electron from a molecule of chemical vapor. The resultant ion is a charged particle that is detectable by various instrumentation such as photo ionization or flame ionization detectors. 

We have already met the Auger process at the beginning of this chapter (Fig. 3.2) as a way in which photo-ionized atoms relax to ions of lower energy. However,... 

Figure 9.18 Morse curve of a diatomic H2. Photo-ionization occurs following photo-excitation to a high-energy state that has no bonding character...

Experimentally, we often want to ionize a molecule, e.g. for photo-ionization spectroscopy. In which case, a sample is bombarded with energetic photons of UV (i.e. short wavelength) or low-energy X-rays. 

Fig. 7.15. Photophysics associated with x-ray photoelectron spectroscopy and x-ray fluorescence. As illustrated, in the XPS experiment one monitors the energy of the electron ejected from the M shell upon photoionization (process 1). In the XRF experiment, one monitors the fluorescence emitted from either the M shell after photoionization (process 2a), or from the L shell after photo ionization and radiationless decay (process 2b).

If reasonable amounts of negative quarks could be had in a sample, energetic photons just above the threshold can ionize the quark to a free state with moderate kinetic energy. One advantage of such an experiment liberating photo-ionized quarks is that a high-resolution spectrometer (or related multi-channel device) can detect the well-defined X-rays emitted by the capture of the quark to a definite heavy atom (such as gold or thorium). 

Positive ions are usually generated in these techniques, as in mass spectrometry, by electron bombardment. Photo-ionization, laser desorption and chemical ionization have also been used for specific applications. When the ionizing energy is above the ionization potential of the parent compound, this procedure may result in the formation of several fragment ions. Collisions of parent and fragment ions with neutral molecules may then give rise to a sequence of chemical reactions. 

Table 4. Ionization energies in eV of the (J = 3/2) component of the 2 p shell of potassium obtained by photo-electron spectrometry, and corrected for the quasi-stationary positive potential of the non-conductors loosing electrons...

It is rather difficult to have preconceived ideas about the order of M.O. energies from Eq. (4). The closest analogy of a dioxo complex with unusually short internuclear distances may be C02 having the ionization energies (in eV) determined by photo-electron spectra49)... 

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