Magnetic dipole interaction and line widths in NQR: 35Cl NQR spectrum of chloroform

Abstract

35 Cl NQR spectra of CHC1 3 and CDCl 3 have been recorded at 77 K with an injection and phase-locked NQR spectrometer. The theoretical 35Cl NQR spectrum of CHC1 3 has been computed with the inclusion of H-C1 intramolecular magnetic dipole Interaction In the quadrupole Hamiltonian. It has been possible to obtain the H-C1 internuclear distance in the CHC1 3 molecule by assuming that contributions to 35Cl NQR line width from static electric effects and relaxation effects are the same in CHC1 3 and CDCl 3 and that the magnetic dipole interaction contribution to 35Cl NQR line width in CDCl 3 is negligible. The calculated H-C1 distance values are: 2.34 Å for the ‘a’ site and 2.49 Å for the ‘b’ site. These values may be compared with the x-ray value of 2.31 Å. It has also been possible to assign the observed NQR frequencies to the appropriate chlorine sites in the unit cell.