Pulsed spectrometer for nuclear quadrupole resonance for remote detection of nitrogen in explosives

Abstract

We describe a pulsed spectrometer for detection of nuclear quadrupole resonance on the nuclei of nitrogen N-14 with fast Fourier transform. The use of a multipulse sequence, four channel system for data registration and processing permits detection of the nuclear quadrupole resonance (NQR) signal in the presence of strong interference and the piezo effect. Using this spectrometer we registered the NQR signal from an explosive sample of 150 g (92% RDX) at a distance of 22 cm, and the time of detection was 81 s.

The application of single particle aerosol mass spectrometry for the detection and identification of high explosives and chemical warfare agents

“…9 NQR detection has also been modified for standoff detection by adapting the receiving and transmitting coils and using a narrow bandwidth for detection. 11 The main disadvantage of bulk detection systems is the significant amount of explosive necessary to trigger an alarm (e.g. enough explosive, wires, or detonation material present to be seen in visible images); trace detection is advantageous since trace levels of explosives (e.g.…”

A new conjugated polymer with donor-acceptor architectures based on alternating 1,4-divinyl-2,5-dioctyloxybenzene and 5,8-(2,3-dipyridyl)-quinoxaline: Synthesis, characterization, and photoinduced charge transfer

“…!-conjugated polymers with donor-acceptor architectures are currently of interest because the intramolecular charge transfer can facilitate ready manipulation of the electronic structure (HOMO/LUMO levels), leading to small band-gap semiconducting polymers [17][18][19][20]. In addition, conjugated polymers have been proven quite useful in creating highly sensi-tive fluorescent chemical sensors [21][22][23]. The conjugated polymer backbone allows efficient electron delocalization and exciton migration over large distances, thereby creating amplified sensory responses compared with small-molecule-based sensors.…”

The Frequency Offset Effects of NQR of Spin I = 1 for Remote Detection

“…One method for increasing the SNR is the application of multipulse sequences. Presently the pulse NQR method is used for the remote NQR detection of explosives [3]. It is very difficult to attain the optimal condition for the observation of the temperature of the sample and the optimal parameters of the pulse sequence in case of remote detection.…”

“…It is very difficult to attain the optimal condition for the observation of the temperature of the sample and the optimal parameters of the pulse sequence in case of remote detection. Presently one tries to optimize the multipulse sequence parameters via the computation of the experimental data [4], using the experimental data [3]. The frequency offset effects are important in these data.…”