Diatom stretching dependence

Effect of Diatom Stretching Dependence. The features of the poten-tial energy surface most central to a discussion of its effect on the predissociation process are not the individual radial strength functions V j((R), but rather the vibrational matrix elements (integrated over the diatom bond length) of the full potential... 

First, diatomic molecules are usually adsorbed on cations (some exceptions to this empirical rule are mentioned in the case studies). The type of interaction and the resulting vibrational perturbation (purely electrostatic or with some orbital overlap contribution) depend on the charge carried by the cation and by the anions in nearest-neighbor positions and on the electronic structure of the cation (with or without d electrons). As a typical example of the effect of a purely electrostatic perturbation on the stretching mode of a diatomic molecule, we mention the classic case of CO adsorbed on Na+ exposed on NaCl (100) (Fig. 2), in which it is clearly shown that the frequency of adsorbed CO is distinctly blue shifted with respect to that of CO gas (2143 cm-1) (48). More general considerations concerning the role of the electrostatic field in perturbing the adsorbed molecules are discussed elsewhere (12-15, 21-23). 

SFCCCC Calculations of Ar-Ho Atom-Vibrating Rotor vdW Complex. A more complete description of the rotational predissociation dynamics in vdW molecule should In principle also include the effect of diatom (H2) bond stretching. Currently only one potential surface, the 803(6,8) potential of Carl and LeRoy( ), contains detailed Information about Its dependence on the length of the diatom bond. The 803(6,8) Ar-H2 potential ( ) Is expanded in the form... 

For a diatomic molecule, the crossing of two potential curves depends on only one coordinate, the intemuclear separation. However, for a polyatomic molecule there are multiple coordinates to consider. For example, the radical CHj is of C2v symmetry and has the triplet electronic states of A2 and symmetry. The molecule CH2 has three normal modes of vibration, namely, the symmetric stretch g, the symmetric bend Q2,... 

Each polyatomic ion or molecule has its own specific set of vibrational frequencies, and different polyatomic ions or molecules have different sets of vibrations. The number of absorptions depends on the number of atoms in the polyatomic ion or molecule and on the structure or specific arrangement of the atoms. The intensity of these absorptions depends on the kinds of atoms. For a diatomic molecule such as hydrogen chloride, HCl, only one simple vibrational pattern called a fundamental mode is possible. This involves the stretching and compression of the bond between the two atoms as shown in FIGURE 42.1a. For molecules with a greater number of atoms, the vibrational motion appears more complex, but is still comprised of a rela-... 

Consider a diatomic molecule, XY. The vibrational frequency of the bond depends on the masses of atoms X and Y, and on the force constant, k, of the bond. The force constant is a property of the bond and is related to its strength. If we return to stretching a spring, then the force constant is a measure of the stiffness of the spring. If atoms X and Y are of similar mass, they contribute almost equally to the molecular vibration. However, if the masses... 

The first solution, q, is the symmetric stretch, with the end atoms (a and c) moving in opposite directions while the central atom (b) remains still. The vibrational constant wj therefore depends only on the mass ma and in fact is essentially the same as would be measured for a diatomic molecule with the same potential energy curve, except that the mass of atom a is used instead of the reduced mass. 

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