NUCLEAR MAGNETIC RESONANCE OF Xe$sup 129$ IN NATURAL XENON
NUCLEAR MAGNETIC RESONANCE OF Xe$sup 129$ IN NATURAL XENON
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天然氙中 Xe$sup 129$ 的核磁共振
DOI：
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发表时间：
1961
期刊：
影响因子：
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通讯作者：
H. Carr
中科院分区：
文献类型：
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作者：
R. L. Streever;H. Carr
Xe/sup 129/ 的自旋晶格弛豫时间T/sub i/ 被测量为液体中温度的函数和气体中压力的函数。发现了在恒定频率但变化的样品密度 p 下共振所需的外场的强烈位移 DELTA H。当样品密度在 48 atm 以上区域增加时，DELTA H 在 8060 高斯场中以 3.45 毫高斯/马加特（标准条件下的密度）的速率线性下降。在液体中，UPSILON /sub 1/ 和 p 的乘积的温度依赖性可以通过 0.7 正负 0.1 kcal/mol 的活化能来描述。在室温和 48 至 73 atm 的气体中，UPSILON /sub 1/ 变化为 p/sup -2.//sup 1 s/sup 0.4/。对于 48 atm 的气体样品，观察到的 UPSILON /sub 1/ 的最大值为 2600 正负 600 秒，在 -101 ℃ 的液体中，最短值为 57 正负 2 秒。 UPSILON /sub 1/ 的实验值与稀有气体和高密度液体两种极限情况下的理论预测进行了比较。在这两种情况下，实验值虽然比之前报道的值大，但仍然比分子间核磁偶极子相互作用的预测值小两到三个数量级。发现弛豫时间与场无关。讨论了数据对于确定松弛机制的影响。有人认为，弛豫可能是由碰撞过程中不对称电子电荷分布的运动引起的原子核波动磁场引起的。 （授权）« 少
The spin-lattice relaxation time T/sub i/ of Xe/sup 129/ was measured as a function of temperature in the liquid and as a function of pressure in the gas. A strong shift DELTA H in the external field required for resonance at constant frequency but varying sample density p was discovered. As the sample density increases in the region above 48 atm, DELTA H decreases linearly at the rate of 3.45 milligauss per amagat (density at standard conditions) in a field of 8060 gauss. In the liquid the temperature dependence of the product of UPSILON /sub 1/ and p can be described by an activation energy of 0.7 plus or minus 0.1 kcal/ mole. In the gas at room temperature and 48 to 73 atm, UPSILON /sub 1/ varies as p/sup -2.//sup 1 s/sup 0.4/. The largest value of UPSILON /sub 1/ ob served was 2600 plus or minus 600 sec for a gas sample at 48 atm, and the shortest value was 57 plus or minus 2 sec in liquid at -101 deg C. The experimental values of UPSILON /sub 1/ were compared with theoretical predictions in two limiting cases, the rare gas and the dense liquid. In both casesmore » the experimental values, although larger than previously reported values, are still two to three orders of magnitude smaller than predicted from an intermolecular nuclear magnetic dipole interaction. The relaxation time was found to be independent of field. Implications of the data for determining the relaxation mechanism are discussed. It is suggested that the relaxation may be caused by a fluctuating magnetic field at the nucleus resulting from the motion of nonsymmetrical electronic charge distributions during collisions. (auth)« less