Nuclear quadrupole resonance

About: Nuclear quadrupole resonance is a research topic. Over the lifetime, 3531 publications have been published within this topic receiving 38801 citations. The topic is also known as: Nuclear quadrupole resonance spectroscopy & NQR.

14N nuclear quadrupole resonance and relaxation measurements of sodium nitrite

Abstract: Measurements of the quadrupole coupling constant, asymmetry parameter, inverse linewidth parameter T*2, spin–spin relaxation time T2, and spin–lattice relaxation times T1s and T1l are reported for sodium nitrite in the temperature region from 77–467 °K. The relations between the spin–lattice relaxation times and the transition probabilities W+, WΔ, and W− are derived for a spin one system, and the transition probabilities are calculated from the T1 data. The results are compared with other NaNO2 studies and support the work of Avagadro et al. in the temperature region near the ferroelectric phase transition. They also indicate the existence of short‐range order above this transition.

Active Q-damping sub-system using nuclear quadrupole resonance and nuclear magnetic resonance for improved contraband detection

Abstract: A Q-damping subsystem for either an NQR or NMR contraband detection receiver for effectively reducing the dead time and increasing sensitivity of the contraband detection system. The invention acts as an addition to the standard transmit circuits of NQR and NMR based scanners and spectrometers. The active Q-damping devices require additional circuitry for an NQR/NMR detection receiver and a programming for the control thereof. Typically, the detection receiver generates a high-voltage RF pulse on the order of 200-1000 V with normal operation of 100-300 microseconds in length to provide sufficient magnetic field characteristics to perturb the precessing nuclei. The NQR or NMR detection receiver electronics are very sensitive and have to detect a very weak nuclear induction pulse signal that is in the nano/micro-volt range. The invention encompasses several embodiments of the detection receiver with the Q-damping subsystem which include: a transformer coupled resistive damping circuit; an inductively coupled resistive damping circuit; a shunt capacitor/resistor damping circuit; a grounded shunt capacitor/resistor damping circuit; a common mode choke transient suppression damping circuit; a multi-stage Q-damping circuit; and a full-wave Q-damping circuit.