一种精密的边限振荡器型NQR谱仪及其应用(英文)

A PRECISION MARGINAL OSCILLATOR - TYPE NQR SPECTROMETER AND IT'S APPLICATION

本文介绍一种精密的场效应管边限振荡器型核四极矩共振(NQR)谱仪。工作频率范围14MHz～35MHz,分段连续可调。这种谱仪的灵敏度高、波形失真小。在室温下,多晶粉未状氯酸钾样品中^(35)Cl的NQR频率测量精度大约3×10^(-6)。重结晶样品中^(35)Cl的NQR谱一次微分信号信噪比S/N≥150。用该谱仪对KClO_3、NaClO_3、NaCl样品进行测试,得到氯的同位素^(35)Cl和^(37)Cl的四极耦合常数比(eQq)^(35)Cl/(eQq)^(37)Cl的实测值分别为 1.2687363、1.2687306、1.2687361。在77K到393K温度区间测量了氯酸钾多晶粉未状样品中^(35)Cl的NQR共振频率和温度的关系,在冰水混合温度附近,温度每变化0.1K,NQR频率的变化是478Hz。

A precision marginal oscillator-type nuclear quadrupole resonance (NQR) spectrometer using field effect transistors (JFET'S) is described in this paper. The frequency is succesivcly adjustable by several ranges from 14 MHz to 35 MHz, This spectrometer shows a high sensitivity and small wave shape distortion. At room temperature, the measuring accuracy of NQR frequency of ^(35)Cl in polycrystallinc powder of potassium chlorate sample is about 3 ?? 10^(-6), the signal to noise ratio (S/N) of NQR spectrum of ^(35)C1 in recrystallized sample is greater Than 150. The obtained chlorine's quadrupolc coupling ratio (eQq) ^(35)Cl/(eQq) ^(37)Cl in potassium chlorate, sodium chlorate and sodium chloride art 1.2687363, 1.2687306 and 1.2687661 respectively. The relation of nuclear quadrupole resonance frequency and temperature have been studied by ^(35)Cl in polycrystalline powder sample when the temperature was varied from 77 K to 393 K