A method for determining a property of a substance in a downholemeasurement region includes the following steps: providing a static magneticfield having a static magnetic field gradient in the measurement region;applying,in the measurement region, a pulse sequence that includes a tipping pulse, are--focusing pulse, and a pulsed field gradient pulse train; wherein thepulsed fieldgradient pulse train includes a first portion and a second portion; the firstportioncomprising a first pulse or set of pulses having a first polarity and a secondpulseor set of pulses having a second polarity, the second polarity being oppositetothe first polarity, and wherein the first portion occurs before the re-focusing pulse;the second portion comprising a third pulse or set of pulses having the firstpolarity and a fourth pulse or set of pulses having the second polarity, andwherein the second portion occurs after the re-focusing pulse; and receivingoneor more spin echoes from the measurement region.
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