T1-weighting of Hahn echo-trains in the stray-field for deuterium: prospects for imaging using long echo-train summation.
Hahn-echoes have been observed in stray-field gradients of 37.5 T/m and 74.5 T/m for deuterium in heavy water in a number of forms: liquid, ice, and coordinated in solid copper sulfate and silica gel. In the diamagnetic samples, the application of many pulses (> 1000 or more) in long pulse-trains produced many sustained echoes. This lengthening of T(echo) is caused by T1-weighting of the components of the Hahn echo (even in the absence of spin-locking). In contrast, for the paramagnetic complex, the shortening of T1 greatly reduces T(echo) and only few echoes are obtained. A new protocol for stray field imaging is suggested when T1 is long: long echo-train summation (LETS). The observed magnetisation is much greater for heavy ice than for heavy water because the line-width, and hence the thickness of the excited slice, is greater.
Randall
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ICTPOL/IST, Departamento de Engenharia de Materiais, Lisboa, Portugal.
Nunes
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TG
Guillot
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Bodart
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PR
D019327:Copper Sulfate / Q000032:analysis; D003903:Deuterium / Q000032:analysis*; D004578:Electron Spin Resonance Spectroscopy; D005782:Gels; D012822:Silicon Dioxide / Q000032:analysis
D005782:Gels; D012822:Silicon Dioxide; D003903:Deuterium; D019327:Copper Sulfate