tag:blogger.com,1999:blog-3300702123878659843.post8977261371665761507..comments2024-03-26T05:25:50.831-04:00Comments on University of Ottawa NMR Facility Blog: Dead Time and PhaseGlenn Faceyhttp://www.blogger.com/profile/05146575170575279335noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-3300702123878659843.post-25831285769823919262023-05-16T14:26:20.678-04:002023-05-16T14:26:20.678-04:00EF,
I’m not sure about a specific formula which wo...EF,<br />I’m not sure about a specific formula which would account for both the zero order and first order phase corrections as a function of the number of points removed from the beginning of an FID as the first order correction will depend on the observe pulse duration and how far off-resonance a peak is observed. Perhaps this post will help:<br /><br />http://u-of-o-nmr-facility.blogspot.com/2011/01/first-order-phase-errors.html<br /><br />GlennGlenn Faceyhttps://www.blogger.com/profile/05146575170575279335noreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-24782889725813952482023-05-16T10:21:23.643-04:002023-05-16T10:21:23.643-04:00Hi, is there any formula that relates the phase ch...Hi, is there any formula that relates the phase change in the frequency domain with the time shift in the time domain? I've been playing around by cropping the initial points of the FID and noticed that for certain number of cropped points a zeroth order correction does the job, but in other cases one needs first order phase correction. I couldn't find any literature about this.EFhttps://www.blogger.com/profile/14612367718527984885noreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-45932250250354851332020-04-21T09:45:43.648-04:002020-04-21T09:45:43.648-04:00Bottle,
Phasing and baseline problems are very com...Bottle,<br />Phasing and baseline problems are very common in solid-state NMR spectra acquired with short dwell times due to probe ringing or dead time problems. You can delete the bad points at the beginning of the FID and FT the it. Phase the intense centerband with zero-order phase correction and phase the sidebands with first order phase correction. The first order correction will likely be very large and will leave your spectrum with extreme baseline problems. These problems can be corrected with a baseline correction routine applied to the spectrum. You may have better luck by using backward linear prediction to predict the bad points in the FID. Another option is described in this post:<br /><br />https://u-of-o-nmr-facility.blogspot.com/2007/11/baseline-correction-in-satellite.html<br /><br />Essentially you delete all of the FID points up to the top of the first rotational echo then FT the FID. It should be easy to phase and the baseline should be acceptable. Of course, you throw away all of the information between the beginning of the FID and the first rotational echo. You may lose broad features in your spectrum.<br /><br />GlennGlenn Faceyhttps://www.blogger.com/profile/05146575170575279335noreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-75584729078596404712020-04-16T16:56:52.298-04:002020-04-16T16:56:52.298-04:00Dear Glenn Facey,
I acquired an Al27 NMR on my sam...Dear Glenn Facey,<br />I acquired an Al27 NMR on my sample. The spinning speed is 27.5KHz. Dwell time is 0.8us. Deadtime is 8us. I lost some FID points at the beginning of my signal. And now it's hard to phase my spectra properly, especially the spinning sidebands. Could you please inspire me on how to phase it correctly?Bottlehttps://www.blogger.com/profile/10839399410029544067noreply@blogger.com