Ionization inner valence orbitals

In this section, we present an overview of the photoabsorption cross section (o ) and the photoionization quantum yields (rh) for normal alkanes, C H2 +2 ( = 1 ), as a function of the incident photon energy in the vacuum ultraviolet range, and of the number of carbon atoms in the alkane molecule, because normal alkanes are typical polyatomic molecules of chemical interest. In Fig. 5, the vertical ionization potentials of the valence electrons, which interact with the vacuum ultraviolet photons, in each of these alkane molecules are indicated to show how the outer- and inner-valence orbitals associated with carbon 2p and 2s orbitals, respectively, locate in energy [7]. 

Although originally mainly the more pronounced near-edge features were observed and compared or interpreted (usually empirically), it is evident from a recent review (18) that today considerably greater emphasis is given to the study of the extended fine structure. This stands in relation to the improved experimental methods for detection of weak modulations and to the currently more advanced theoretical description of the EXAFS part of the spectrum. Complete understanding of the Kossel structure at the threshold part of an element s inner-shell spectrum, which contains among others valence orbital, ionization, and chemical shift information, is relatively slow due to the... 

Table 13 Calculated (ADC(3)) energies (E, eV) and Intensities (P) of the outer- and Inner-valence orbital vertical Ionization transitions In thiophene ...

Ionization of inner valence orbitals In this regime, where several matrix elements have comparable strength, the self energy has a sequence of poles, and has several solutions with comparable residues. A qualitative explanation is given in Fig 3 there are configurations shown in part (b) of the figure that have the same energy as the hole state shown in part (a). 

Iron cloud lies closer to the nucleus than the periphery of the completed 4d subshell. The valence electron is shielded from the positive nucleus only incompletely, thus being held more firmly (ionization potential 7.57 ev), than is the valence electron in the rubidium atom (ionization potential 4.19 ev), for which the shielding is more nearly complete. Likewise, there is attraction between the incompletely shielded nuclear charge of one atom in silver metal and the peripheries of the electron clouds of adjacent atoms and breakup of the metal structure to the individual atoms is far more difficult for silver (heat of sublimation 67 kcal per gram-atom) than for any of the alkali metals (heats of sublimation ranging from 20 to 36 kcal). If any one factor may be said to explain the nobility of the coinage metals, it would thus be the incomplete shielding of the valence electron by the inner d orbitals. 

The effects of V -Vg mixing lowers this peak Into the discrete spectral region, where It correctly corresponds to the strong b E resonance (24). It Is of Interest to note that the o orbital in N2 also contributes to the K-edge cross section (26), and to Inner-valence channels associated with 20g Ionization (27). Since these aspects of photolonlzatlon of N2 are so well documented In the literature (22-27), they are not reported explicitly here. 

The 4-3IG basis set is not exactly a double zeta basis since only the valence functions are doubled and a single function is still used for each inner shell orbital. It may be termed a split valence shell basis set. The inner shells contribute little to most chemical properties and usually vary only slightly from molecule to molecule. Not splitting the inner shell functions has some effect on the total energy, but little effect on dipole moments, valence ionization potentials, charge densities, dissociation energies, and most other calculated quantities of chemical interest. The 4-3IG basis thus consists of 2 functions for H and He, 9 functions for Li to Ne, 13 functions for Na to Ar,..., etc. For hydrogen the contractions are... 

In addition to the main lines in the spectrum associated with the outer valence orbitals, the calculations predict interesting satellite structures as well as the appearance of multiple structure in the inner valence region. In the inner valence region a main line may cease to exist. Its intensity can be distributed over many ionic states, giving rise to the breakdown of the orbital picture of ionization. This phenomenon has been found to be common to most molecular systems. For a thorough discussion of this phenomenon we refer to Ref. 32. 

The calculations were performed using a double-zeta basis set with addition of a polarization function and lead to the results reported in Table 5. The notation used for each state is of typical hole-particle form, an asterisc being added to an orbital (or shell) containing a hole, a number (1) to one into which an electron is promoted. In the same Table we show also the frequently used Tetter symbolism in which K indicates an inner-shell hole, L a hole in the valence shell, and e represents an excited electron. The more commonly observed ionization processes in the Auger spectra of N2 are of the type K—LL (a normal process, core-hole state <-> double-hole state ) ... 

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