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posted Jun 29 '11 at 12:17

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renee
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I am not sure what you're trying to accomplish, but a pw of 2-4 us doesn't sound correct to me... A pulse of 4 us would correspond to ~12.5 kHz field; garp1 decouples properly over 2.5 times this value (see for example the book of Cavanagh, p. 204-209). If you are using garp1 as decoupling sequence then the "tip_angle resolution" should be equal to 1.0 (see the Varian command and reference parameter book or look in the .DEC file); so there is no point in putting this at 2.0 You should figure out over what field strength you need to decouple the proton range, then get determine at which power you need to apply the garp1 sequence and determine the pw at this field. Also, in your sequence make sure that you actually change the power to the appropriate level; you do not want to do decoupling at full power! Just my thoughts... explaining a bit more what you're trying to do (are we talking about solution state NMR, protein, etctera) might help.
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posted Jun 29 '11 at 12:21

renee's gravatar image

renee
56

I am not sure what you're trying to accomplish, but a pw of 2-4 us doesn't sound correct to me... A pulse of 4 us would correspond to ~12.5 kHz field; garp1 decouples properly over 2.5 times this value (see for example the book of Cavanagh, p. 204-209). If you are using garp1 as decoupling sequence then the "tip_angle resolution" should be equal to 1.0 (see the Varian command and reference parameter book or look in the .DEC file); so there is no point in putting this at 2.0

You should figure out over what field strength you need to decouple the proton range, range (at least I assume that's what you're trying to do?), then get determine at which power you need to apply the garp1 sequence and determine the pw at this field. Also, in your sequence make sure that you actually change the power to the appropriate level; you do not want to do decoupling at full power!

Just my thoughts... explaining a bit more what you're trying to do (are we talking about solution state NMR, protein, etctera) might help.

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