Nitrogen electric dipole transition

For clarity it is emphasized that the effect occurs because the transition state develops an electric dipole. Neither nitrogen nor methane has a dipole in the gas phase, but when interacting with the metal electrons they develop one. With nitrogen the dipole is opposite that of the alkali adsorbate, while for methane it is in the same direction, leading to promotion and inhibition respectively. 

Carbon Monoxide. There are close similarities between carbon monoxide and nitrogen. The molecules are isoelectronic, and the bond lengths and dissociation energies are quite comparable. The phase diagrams of the two compounds show the same trends in the moderate pressure range with a variety of phase transitions between essentially alike crystal structures [333], when allowance is made for the lack of the inversion center and the presence of a weak electric dipole moment in carbon monoxide. However, the behavior and stability at higher... 

The benzene and azabenzenes form iso-electronic series of molecules, as naphthalene and the azanaphthalenes also do. The ground state electronic and geometric structures are therefore quite similar within one series. The substitution of CH groups with nitrogens introduces lone-pair to 7r transitions, and lowers the benzene and naphthalene symmetries. Small and systematic trends are found for linear response properties of the azabenzenes [189]. Each molecule is, however, very specific with respect to phosphorescence due to the delicate nature of the SOC and electric dipole activity interactions. 

An infrared spectrum thus represents the attenuation of the incident radiation as a function of frequency each absorption band corresponding to a jump between two vibrational levels and a specific vibrational movement. Moreover, the activity (a mode is said to be active when the corresponding absorption band can be detected) of the vibrational mode depends on the variation in an electrical property of the molecule, namely its dipole moment. In the case of a homonuclear molecule, such as N2 for example, the electrical symmetry is maintained during the elongation movement along the axis which connects the two nitrogen atoms and the corresponding absorption transition is prohibited. 

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