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Hi Jean, as far as I know, PHC0 = -rp and PHC1 = -lp. I never had any problems converting the phase values that way. The pivot point is only used to determine the point in the spectrum whose "overall phase correction" (frequency-independent zero-order and frequency-dependent first-order) does not change while correcting the first-order phase. So when changing the zero-order value, the position of the pivot point does not have any influence at all. But when correcting the first order, the position of the pivot point marks the area where there is no change in the phase, so that you can correct the phase looking at a signal far away. After this second step, you phase correction is done.

Hi Jean,

as far as I know, PHC0 = -rp and PHC1 = -lp. I never had any problems converting the phase values that way.

The pivot point is only used to determine the point in the spectrum whose "overall phase correction" (frequency-independent zero-order and frequency-dependent first-order) does not change while correcting the first-order phase. So when changing the zero-order value, the position of the pivot point does not have any influence at all. But when correcting the first order, the position of the pivot point marks the area where there is no change in the phase, so that you can correct the phase looking at a signal far away. After this second step, you phase correction is done.

So just to explain the meaning of the pivot point, a possible way of correcting the phase of the spectrum would be:

1.) Change the zero-order phase looking at one signal. This one signal should preferably be at one end of the spectrum and it should be strong enough to be able to nicely phase it correctly.

2.) Once this signal is phased nicely (using zero-order only!) you set the pivot point manually directly on that signal. Now you never touch the zero-order correction again and only change the first order. You will see that no matter how much you change the first order, the chosen signal will not change its phase. This is because the program (TopSpin, VNMRJ, ...) automatically recalculates the zero-order phase so that the overall phase at the position of the pivot peak does not change. This behaviour can now be used to find the correct first-order value: Look at a signal at the other end of the spectrum (the further away from the pivot point, the better) and change the first-oder correction until the phase is okay.

Then you are done.

Hi Jean,

as far as I know, PHC0 = -rp and PHC1 = -lp. I never had any problems converting the phase values that way.

The pivot point is only used to determine the point in the spectrum whose "overall phase correction" (frequency-independent zero-order and frequency-dependent first-order) does not change while correcting the first-order phase. So when changing the zero-order value, the position of the pivot point does not have any influence at all. But when correcting the first order, the position of the pivot point marks the area where there is no change in the phase, so that you can correct the phase looking at a signal far away. After this second step, you phase correction is done.

So just to explain the meaning of the pivot point, a possible way of correcting the phase of the spectrum would be:

1.) Change the zero-order phase looking at one signal. This one signal should preferably be at one end of the spectrum and it should be strong enough to be able to nicely phase it correctly.

2.) Once this signal is phased nicely (using zero-order only!) you set the pivot point manually directly on that signal. Now you never touch the zero-order correction again and only change the first order. You will see that no matter how much you change the first order, the chosen signal will not change its phase. This is because the program (TopSpin, VNMRJ, ...) automatically recalculates the zero-order phase so that the overall phase at the position of the pivot peak does not change. This behaviour can now be used to find the correct first-order value: Look at a signal at the other end of the spectrum (the further away from the pivot point, the better) and change the first-oder correction until the phase is okay.

Then you are done.

So ideally, a 1D-spectrum has two phase correction values that can be found in the way I just described. And which these values are is completely irrelevant to where you put the pivot point. They are always the same.