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

Abstract

³⁵Cl NQR spectra of CHC1₃ and CDCl₃ have been recorded at 77 K with an injection and phase-locked NQR spectrometer. The theoretical ³⁵Cl NQR spectrum of CHC1₃ 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 CHC1₃ molecule by assuming that contributions to ³⁵Cl NQR line width from static electric effects and relaxation effects are the same in CHC1₃ and CDCl₃ and that the magnetic dipole interaction contribution to ³⁵Cl NQR line width in CDCl₃ 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.