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Due to the quantum signal perturbation, the measurable quantities fluctuate fiercely.


Quantum Signal Processing (QSP) beamformer is insensitive to DOA errors, thus it can achieve stable output performance in such circumstance.


Other applications of Naimark's theorem in the context of frames include feasibility issues for von Neumann measurements in quantum signal processing.




 The method of determination of the phase cycle in PFT NMR experiments from the desired coherence transfer pathway was introduced. A computer program PHASE. BAS used to assist design phase cycling procedure based on this method was proposed. The program has been used to design a 128 step phase cycling procedure for the one and two dimensional INADEQUATE experiments. The one and two dimensional INADEQUATE spectra of nButanol were recorded by using this 128 step phase cycling procedure and a 32 step one collected... The method of determination of the phase cycle in PFT NMR experiments from the desired coherence transfer pathway was introduced. A computer program PHASE. BAS used to assist design phase cycling procedure based on this method was proposed. The program has been used to design a 128 step phase cycling procedure for the one and two dimensional INADEQUATE experiments. The one and two dimensional INADEQUATE spectra of nButanol were recorded by using this 128 step phase cycling procedure and a 32 step one collected in the Broker MSL Pulse Sequence LibraryINADSYMQ. PC respectively. The experimental results show that the former is superior to the latter in suppressing the single quantum signals and eliminating the imperfection of the spectrometer. It seems that the program could be an useful tool in the designing of pulse sequences, especially for the pulse sequences in which huge phase cycle steps are required.  本文介绍了通过选择相干传递路径来计算相位循环的理论依据。在此基础上提出了一个计算机程序PHASE.BAS用于计算相位循环。使用此程序设计了一个128步的相循环用于一维和二维INADEQUATE实验。实验结果表明此相循环能很好地消除单量子信号、压制t_1噪声,其效果明显优于Bruker MSL脉冲序列库中的32次循环的结果。  Raman Magnetic Resonance (RMR) spectroscopy for a heteronuclear AX3 spin system isrecorded by perturbing the highestorder quantum coherence state. The RMR experimentshows that an effective way for detecting higherorder quantum transitions is to prepare thehigherorder multiple quantum (MQ) coherence in the initial state. The product operatorformalism provides an exact method to predict arbitrary order MQ frequencies and intensitiesof RMR spectroscopy. By means of accumulation of Positivenegative... Raman Magnetic Resonance (RMR) spectroscopy for a heteronuclear AX3 spin system isrecorded by perturbing the highestorder quantum coherence state. The RMR experimentshows that an effective way for detecting higherorder quantum transitions is to prepare thehigherorder multiple quantum (MQ) coherence in the initial state. The product operatorformalism provides an exact method to predict arbitrary order MQ frequencies and intensitiesof RMR spectroscopy. By means of accumulation of Positivenegative alternate offset, thestrong single quantum signals are suppressed and hence the MQ transition signals can be detected with a higher efficiency.  研究了异核AX3自旋体系的初始态为最高阶量子相干态时的Raman磁共振谱．研究表明，唯有制备高阶多量子相干的初始态时才有可能对高阶多量子跃迁进行有效检测．积算符理论的精确性使得理论上准确地预言了Raman磁共振谱中各阶多量子跃迁频率、谱线强度，使得各阶多量子跃迁频率相互交错时仍有可能解析谱图．在Raman磁共振实验中采用了正负频偏交替变化采样的方法，对单量子信号进行压制，使其更有效地观察高阶多量子跃迁  Raman magnetic resonance experiment is a useful tool for direct detection of multiple quantum signals in one dimensional mode. It has been shown that all possible order quantum transitions in a spin system may be detected by the method using excitation radiofrequency field with proper offset and strengths. Among these quantum transition signals the single quantum transition signals are usually strongest. The strong single quantum signals may cause problems in dynamic... Raman magnetic resonance experiment is a useful tool for direct detection of multiple quantum signals in one dimensional mode. It has been shown that all possible order quantum transitions in a spin system may be detected by the method using excitation radiofrequency field with proper offset and strengths. Among these quantum transition signals the single quantum transition signals are usually strongest. The strong single quantum signals may cause problems in dynamic range of receiver, spectral baseline roll and phase artifacts. Thus, suppression of strong single quantum signals is necessary to obtain a high quality Raman magnetic resonance spectrum. Here we report an RMR experiment to suppress the strong single quantum signals by alternatively accumulating FID signals with positive and negative irradiation offsets. It follows from the analysis of the product operator formalism that the strong single quantum signals are symmetrical about offset, that is, when irradiation offset changes from positive value to negative, the strong single quantum signals also invert their intensities for a heteronuclear spin system. Therefore, the accumulation of FID with positive and negative irradiation offset can suppress strong single quantum signals in RMR experiments. The RMR experiments with alternative positive and negative offset accumulation acquisition on heteronuclear AX\n(n=1,2,3) spin systems (CHCl\3,CH\2Cl\2,CH\3OH) are carried out on an ARX 500MHz spectrometer, where proton is irradiated and canbon 13 is detected. The experimental results show that the strong single quantum signals are suppressed effectively and the multiple quantum signals with intensity similar to those of the single quantum signals are acquired. This is in a good agreement with the above theoretical prediction. \;  通常单量子信号的强度在Raman磁共振谱中要比其它多量子信号的强度大得多 ,因而易引起接收机饱和 ,使信号发生变形 ,不利于多量子信号的检测 ,因此压抑强的单量子峰是必要的 .积算符理论分析表明 ,异核体系Raman磁共振谱的单 ,多量子峰的共振频率及其信号强度关于频偏满足对称关系 :当频偏由正变为负时 ,单量子信号的强度亦随之改变了符号 .因此 ,对正负频偏 (数值相等 )的两次Raman磁共振实验的FID信号进行累加 ,就可压抑强的单量子峰 ,而对于多量子峰则在大的频偏条件下不会相互抵消 .因此 ,这样的实验累加可以保持多量子信号的强度而压抑掉强的单量子峰 .作为实验验证 ,我们给出了异核AXn 体系 (CHCl3,CH2 Cl2 ,CH3OH)的按上述正负频偏循环累加采样方法得到Raman磁共振1 3C实验谱 .实验结果同理论预言完全一致 .   << 更多相关文摘 
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