Hi, The inversion recovery method whereby the signals plateau at the equilibrium I0 value is very old school. I don't know if anyone records this anymore. Maybe some chemists do. Anyway, I never added support for this because no one was interested or had such data. The new interleaved method resulting in a single exponential from I0 to zero is much better, in that the results are much more reliable. The signals affected by noise are at the end of the exponential rather than in the middle. And the 2 parameter fit is much more reliable for extracting the rate. This is all explained in the original paper, but I can't remember the reference off the top of my head. It should be referenced in the Farrow 94 paper though, which is the basic reference for all R1, R2, and NOE experiments nowadays.
Support could easily be added to relax for this. I actually have coded the relax_fit analysis to support the triple parameter fit curve, but never implemented it. Do you know someone who has measured the R1 in this way? Regards, Edward On 15 June 2011 14:35, Sébastien Morin <[email protected]> wrote: > Hi, > > Talking with some colleagues, I realized that some people record R1 data > with 2D versions of inversion-recovery pulse sequences, where the signal > starts from a negative value to a positive value, with a cross-point at ~ ln > 2 / R1. The equation needed to fit such data is the following: > At = A0 (1-2e^(-R1 t)) > > In relax (and relaxgui), it is assumed that, for both R1 and R2, the user > records data with intensities decaying in an exponential manner (i.e. At = > A0 e^(-R1 t) ). > > Is there a reason why most people use the exponential decay approach, rather > than the inversion-recovery approach ? > > Should relax (and relaxgui) support the inversion-recovery approach ? > > Cheers, > > > Séb :) > > -- > Sébastien Morin, Ph.D. > Postdoctoral Fellow, S. Grzesiek NMR Laboratory > Department of Structural Biology > Biozentrum, Universität Basel > Klingelbergstrasse 70 > 4056 Basel > Switzerland > > > _______________________________________________ > relax (http://nmr-relax.com) > > This is the relax-devel mailing list > [email protected] > > To unsubscribe from this list, get a password > reminder, or change your subscription options, > visit the list information page at > https://mail.gna.org/listinfo/relax-devel > _______________________________________________ relax (http://nmr-relax.com) This is the relax-devel mailing list [email protected] To unsubscribe from this list, get a password reminder, or change your subscription options, visit the list information page at https://mail.gna.org/listinfo/relax-devel
