Potential energy curves Morse

Figure 3.6 shows the Morse potential energy curves for two hypothetical electronic states of a diatomic molecule, the vibrational energy levels for each, and the shape of the vibrational wavefunctions (i//) within... 

Now let us idealize the intersection region of the overlapping Morse potential energy curves as shown in Figure 2.15. In the nonequilibrium situation, we arbitrarily define a and b so that the change in barrier height for the reverse reaction is... 

A simple case is the portrayal of the ground state of the OH radical, see Figure 2.14. For simplicity, we show a part of the Morse potential energy curve with the highest bound and quasibound vibrational levels indicated by solid lines and dashed line, respectively, Figure 2.14a. The spectral density is... 

The Frank-Condon principle is based on the fact that the time of an electronic transition (of the order of 10 s) is shorter than that of a vibration (of the order of 10 s). This means that during an electronic transition the nuclei do not change their positions. This phenomenon can be illustrated using the Morse potential energy curves for diatomic molecules (Figure 2.17). The series of horizontal lines... 

The principles of photoluminescence applied to solid oxide surfaces can be most easily understood by assuming some simplifications. For example, we can start by considering the Morse potential energy curves (Fig. 1) related to an ion pair such as M-+0-, taken as a harmonic oscillator to represent an oxide, typically an alkaline earth oxide. The absorption of light close to the fundamental absorption edge of this oxide leads to the excitation of an electron in the oxide ion followed by a charge-transfer process to create an exciton (an electron-hole pair), which is essentially... 

Figure 2.1 Morse potential energy curves for the neutral and negative-ion states of F2. The vertical electron affinity VEa, adiabatic electron affinity AEa, activation energy for thermal electron attachment E, Err — AEa — VEa, EDEA — Ea(F) — D(FF), and dissociation energy of the anion Ez are shown.

Figure 2.3 Morse potential energy curves for the neutral and negative-ion states of CC14. The new quantity illustrated in this figure is photodetachment energy. It is larger than AEa and is the peak in the photodetachment spectmm. Thermal electron attachment is exothermic, that is, EDEA = a positive quantity. Two other states dissociating to Cl + CC13(—) and the polarization curve are not shown.

HERSCHBACH IONIC MORSE POTENTIAL ENERGY CURVES... 

Figure 2.4 Classification of negative-ion Morse potential energy curves originally presented by Herschbach in 1966. The curves are calculated from actual data. The empty spaces are impossible combinations. These classifications have been modified so that they are symmetrical and all combinations are possible [34, 36].

NEGATIVE-ION MASS SPECTROMETRY AND MORSE POTENTIAL ENERGY CURVES, 1980 TO 1990... 

Figure 4.9 Morse potential energy curves for chloromethane and its ions. The curves are calculated using the activation energy determined from data in Figure 4.8. The high-temperature data is for unimolecular dissociation via the curve crossing on the approach side of the molecule. Only the VEa is negative and dissociation occurs in the Franck Condon transition. The thermal energy dissociation occurs through the thermal activation of the molecule, as is the case for all DEC(l) molecules.

In 1963 negative-ion Morse parameters for the ground-state anions of Br2 and I2 were obtained by estimating D, re, and v from the VEa measured from charge transfer spectra and properties of the excited states of the neutral. Multiple excited states of I2(—) were characterized by D. R. Herschbach in 1966. He presented general forms for ionic Morse potential energy curves (HIMPEC). Nine total groups... 

Figure 7.11 Original Hershbach ionic morse potential energy curves and the modified HIMPEC [2, 3], The curves are calculated for the current best available data. The multiple curves for 02(—) and I2( ) are given to illustrate the relative positions of the curves. The specific example is the curve that is solid.

Figure 7.12 Historical Morse potential energy curves for H2 and its anions, dating back to 1936 [25], 1956 for the excited state [26], 1967 for the polarization ground state [27], and 1981 for the valence excited state [28].

Figure 7.13 Current best Morse potential energy curves for H2 and its anions, from [30-32],...

Figure 7.15 Current best Morse potential energy curves for I2 and its anions. The X axis is the reduced intemuclear distance 5=1 — reJ r, where r is the intemuclear distance and re is the equilibrium intemuclear distance. The data are taken from [18]. The 12 curves were predicted in [23].

Figure 7.18 Current best Morse potential energy curves for naphthalene and its anions. There are four additional antibonding curves that are not shown, giving a total of eight valence-state curves. The adiabatic electron affinity corresponds to the valence state with an Ea of 0.16 eV. The polarization curve has an Ea of about zero.

The homonuclear diatomic molecules are the simplest closed set of molecules. Many of the electron affinities of the main group diatomic molecules have been measured by anion photoelectron spectroscopy (PES), but only a few have been confirmed. These Ea can be examined by their systematic variation in the Periodic Table. Calculating Morse potential energy curves for the anions and comparing them with curves for isoelectronic species confirm experimental values. The homo-nuclear diatomic anions of Group IA, IB, VI, VII, and 3d elements and NO are examined first. 

Electron Affinities and Morse Potential Energy Curves ... 

Figure 9.4 Historical Morse potential energy curves for I2 and I2(—) 1966 [12] and 1985 [8],...

Figure 9.5 Historical absorbance data for the construction of the Morse potential energy curves for the Halogen diatomic anions. The energies indicated by dotted lines were predicted in 1966 [12].

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