Woody -
My first reaction is that the selected audio filter is too
narrow, so that you are getting into the first part of phase roll off
farther from the carrier, which is only approximately second order.
Test: select a wider audio filter.
A second possibility that comes to mind is a non-uniform ADC
sampling rate, which also would give larger phasing errors at higher
frequencies away from carrier.
Happy NMRing !!
- Alan O.
At 8:40 AM -0700 8/2/00, Woodrow Conover wrote:
>Our new JEOL NMR instrument produces data which when phase corrected
>with zero order and first order
>phase corrections still has some peaks which are out of phase. We
>have experimented and found that
>the addition of a second order phase correction parameter allows all
>peaks to be phased. We have
>another example of data from a Varian instrument which has the same
>phasing problems and solution.
>
>
>Is this a general issue with newer NMR instruments or does it just
>show up in a few selected cases?
>
>If a general issue, how does one solve the "not all peaks can be
>phased at the same time" issue?
>
>woody_at_acornnmr.com
Received on Thu Aug 03 2000 - 12:12:28 MST