Magnetic deflection spectrum of vanadium tetrachloride
Magnetic deflection spectrum of vanadium tetrachloride
复制标题
四氯化钒的磁偏转谱
DOI：
10.1021/ja00197a009
复制
发表时间：
1989
期刊：
影响因子：
--
通讯作者：
D. Herrick
中科院分区：
文献类型：
--
作者：
A. Gedanken;N. A. Kuebler;M. Robin;D. Herrick
测量了VC_（14）在稀有气体超声束中的磁偏转谱。结果发现，在较重的稀有气体（Ar，氪，和氘）的Stern-Gerlach分裂模式只是那些预期的自旋二重态的分子，复杂的存在下的非偏转（VC 14）X集群。在这些束流中，未成团的VC_（14）的卫星分裂与束流速度的平方成比例，在Stern-Gerlach谱中没有证据表明该分子在凝聚相的EPR和NMR谱中存在快速的（10 ~（-9）~（123）s）分子内自旋弛豫（ISR）。模拟了ISR对SG偏转谱的影响，并与实验结果进行了比较。结果表明，如果ISR在束冷VC_（14）中起作用，自旋弛豫时间大于10 ~（-4）s。相比之下，接种到He中的VC 14的偏转光谱比预期的要压缩得多，这表明ISR可能在这种情况下起作用。对He束中VC 14的Stern-Gerlach带形的分析表明，如果ISR是导致异常谱的原因，那么ISR时间约为6 s。本文介绍了中性分子质谱的一个实例，即利用磁偏转技术来确定载气与顺磁性目标分子的可能缔合，我们最近利用Stern-Gerlach偏转技术研究了磁性分子与非均匀磁场的相互作用。在这种方法中，磁性分子，无论是纯的或种子到稀有气体，从脉冲阀/双撇渣器安排的问题，以形成一个良好的准直超声分子束之间的梯度磁体的磁极通过。取决于分子的磁性子状态Mj，它可以被场梯度偏转到较高场的区域中，偏转到较低场的区域中，或者根本不偏转。通过将质谱仪调谐到感兴趣的磁性物质的质量，同时在每种情况下在垂直于射束行进的方向但平行于场梯度的方向的方向上平移质谱仪，来测量射束的空间色散。用这种方法，我们已经研究了氧及其团簇1和二氧化氮，一氧化二氮，和一些有机氮氧自由基的磁偏转光谱。2
The magnetic deflection spectra of VC14 seeded into supersonic beams of the rare gases have been determined. It is found that in the heavier rare gases (Ar, Kr, and Xe) the Stern-Gerlach splitting patterns are just those expected for a molecule in a spin-doublet state, as complicated by the presence of nondeflecting (VC14) X clusters. In these beams, the satellite splittings of unclustered VC14 scale with thesquare of the beam velocities, and there is no evidence in the Stern-Gerlach spectra for the rapid (10" 9 123s) intramolecular spin relaxation (ISR) so apparent in the EPR and NMR spectra of this molecule in condensed phases. Modeling of the ISR effect on SG deflection spectraand comparison of these results with experiment shows that if ISR is in any way active in beam-cooled VC14, the spin relaxation time is longer than 10" 4 s. By contrast, the deflection spectrum of VC14 seeded into He is far more compressed than otherwise expected, suggesting that ISR may be at work in this case. Analysis of the observed Stern-Gerlach band shape of VC14 in the He beam shows that if ISR is the cause of the anomalous spectrum, then the ISR time is approximately 6 s. The use of magnetic deflection to determine the possible association of the carrier gases with the paramagnetic target molecule is presented as an illustration of neutral-molecule mass spectrometry.We havebeen involved recently in studying the interactions of magnetic molecules with inhomogeneous magnetic fields using the Stern-Gerlach deflection technique. In this method, the magnetic molecule, used either pure or seeded into a rare gas, issues from a pulsed valve/dual skimmer arrangement to form a well-collimated supersonic molecular beam passing between the poles of a gradient magnet. Depending upon the magnetic substate Mj of the molecule, it may be deflected by the field gradient into the region of higher field, into the region of lower field, or not at all. The spatial dispersion of the beam is measured by tuning a mass spectrometer to the mass of the magnetic species of interest while translating the spectrometer in each case in a direction normal to that in which the beam is traveling but parallel to the direction of the field gradient. Working in this way, we have studied the magnetic deflection spectra of oxygen and its clusters1 and of nitrogen dioxide, nitrous oxide, and some organic nitroxide radicals. 2