Electron Coupled Interaction in Solid Iodine

Abstract

Hyperfine structure in the nuclear quadrupole resonance spectrum of solid iodine observed by Kojima, Ogawa, Hagiwara, Abe and Minematsu is analysed in terms of electron coupled interaction between nuclear spins. Theoretical expression for the Hamiltonian of the electron coupled interaction between two nuclei in an iodine molecule is derived, having the form of J I _{A z} I _{B z} + K ( I _{A x} I _{B x} + I _{A y} I _{B y} ), where z is the bond axis. Electron coupled interactions between nuclei belonging to different molecules in the crystal are neglected. Values of the coupling constants J and K are determined to be both equal to 3.0 kc from the comparison with the experimental data. Electronic structure of the chemical bond is discussed on the basis of the above coupling constants in combination with the previously known quadrupole coupling constants. It is concluded that the bond in an iodine molecule has 22% s character and 33% d character. It is also concluded that there are auxiliary bonds between neighboring molecules with a fractional importance of 10%.