The Quasistationary States in Multipulse NQR

A number of methods for cancelling magnetoacoustic and piezoelectric ringing signals in the spectroscopy of the nuclear quadrupole resonance are presented. The suggested methods include using the sequence (q~0)~-(z-~p~-2z'-q~v-2"r-~o_,-2z-~p_v-z) . anda multipulse analog of the twopulse Hahn sequence with the first pulse replaced by a short steady-state sequence. Another method presented is the method of orthogonal effective fields for a fast saturation of the quadrupole spin system which can be used for subtracting the magnetoacoustic and piezoelectric components from the signal. The suggested methods can be used for the practi~:al purposes of detecting explosive substances and narcotics.

Section: Methods Of Orthogonal Effective Fieldsmentioning

confidence: 99%

Multipulse sequences for explosives detection by NQR under conditions of magnetoacoustic and piezoelectric ringing

Mikhaltsevitch¹,

Rudakov²,

Flexman³

et al. 2004

“…If fa 1 ~ n/2 and rp 2 ~ re/2, the transformation becomes more compticated and the coherente transfer decreases. In the case of the simultaneous two-frequency irradiation the calculations can be considerably simplified with the transition in the new reference frame, in which the sum coŸ q -b coqrsqr can be replaced by single term colSx [10]. This transformation can be carried out by rotation about the commutator [SxPq,S q~] = S 7 since these three operators constitute an SU(2) subgroup.…”

Section: The Technique Of Calculationsmentioning

confidence: 99%

“…(-2pq/co, and sin r = .Oq'/co, are the direction cosines of the rotation axis Si q cos fa + S qr sin fa. In order to conserve the notation of transitions we consider the reference frame rotation [10]. Then the unitary transformation in the Hilbert space can be replaced by simple multiplication of these matrices by symbolic computations with Mathematica, Maple, MATHCAD and others.…”

Section: The Technique Of Calculationsmentioning

confidence: 99%

“…In this paper we would like to presenta simple and effective technique for solving any problem in a three-level system which was used in our previous paper [10] for describing the formation of echo signals in ~4N NQR for the case of a small asymmetry parameter when the two-transition excitation cannot be avoided. In quantum optics the formation of the transient signals with multiple-transition irradiation is described in detail in ref.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Theory of two-frequency excitation in14N NQR

Osokin

Khusnutdinov

2003

Self Cite

“…An increase of the sensitivity due to the decrease of the dead time of the receiver and the ferroelectric ringing of the sample in this case is supposed. The theory of the simultaneous irradiation at two transitions has been published previously [4]. In that paper all the trajectories of spin magnetization transfers in the process of the echo formation have been calculated and are shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Two-frequency composite pulses in NQR

Osokin

Khusnutdinov

2006

Self Cite

The application of multiple-pulse sequences consisting of two-transition composite pulses for remote nuclear quadrupole resonance detection of explosives and narcotics is discussed. The pulse sequence for obtaining these pulses is described and it is shown that these pulses are equivalent to the pulse applied at the third (nonirradiated) transition. The Ioss of the signal intensity in this case is absent.