Nuclear Quadrupole Interactions in Nuclear Quadrupole Resonance Detection of Energetic and Controlled Materials: Theoretical Study

There has been a growing interest in nuclear quadrupole resonance (NQR) techniques useful for the detection of explosives and drugs in solid state systems. This paper uses the first-principles one-electron Hartree-Fock theoretical method to study the nuclear quadrupole interaction parameters e²qQ and η for the ¹⁴N nuclei in the explosives RDX and β-HMX as well as the drugs cocaine and heroin. It has been found in our earlier published investigations reviewed here that there is very good agreement for our calculated e²qQ and η for ¹⁴N, for all these four systems, and experiment. We also present our unpublished theoretical results for cocaine with an HCl molecule attached. We successfully explain quantitatively the drastic decrease in e²qQ in going to cocaine-HCl from cocaine-free base as well as the observed substantial increase in η and discuss the implications of these dramatic changes for NQR detection in general.