1
|
Hello to all,
This time I am having problem with doing a double resonance experiment. The final goal is to do 1H/19F-HOESY, but I am confused in the edasp window:
I remember I was doing 1H/13C heteronuclear shift correlation experiments before. I think for 13C it uses X-transmitter(!) and x100W amplifier. A normal 1D-19F works fine (H50W-X-XBB). It is a NMR300 and a QNP probe. Thanks in advance, Amin |
|
1
|
I think that your edasp setup is probably right for 1H observe, with 19F decouple. To check this out, just run 1H with 19F decoupling (parameter set PROF19DEC, followed by getprosol). Just find a convenient test sample with H-F coupling. If that works, you are O.K. However, there might be some pulse programming issues for a 1H-19F HOESY (I have never actually done one myself). The 1H amplifier is used for both 1H and 19F, but the QNP switchbox routes the signal to the correct preamp, since 19F is done on the X pre-amp/probe input. You will need some real time switching in the pulse programming to switch the 1H amplifier between the H and X ports. Look at pulse sequence zghfigqn to see how this is done. You can also check with Bruker to see if they have a HF HOESY pulse program for a QNP/BBFO type set-up. You will be using the H/F switch in the QNP box which is a pin-diode device with a response of about 5 us, I think. |
|
1
|
OK, I am back with my confusion again! I prepared a sample of CF3CH2OH to check what you recommended. rpar > F19CPD: gives the 19F decoupled with 1H spectrum, and it works. Doing the other way: rpar > PROF19DEC, does not give any signal! getprosol brings an error message that I must use setprosol before. For saving anything inside setprosol window I need the admin password, and I don't know how to edit it. What does getprosol do actually? After reading the parameters for PROF19DEC, wobb brings tuning for 19F (a very noisy one). Shouldn't it run tuning for 1H? (the edasp config window is like the snapshot I posted before). Any help is appreciated, Thank you, Amin |
|
1
|
Parameters read in with "rpar" are generic parameters with no calibrations for any probe/solvent combination. What "getprosol" does is read in all the calibrations for the current probe and solvent. For lower frequency instruments, every solvent may have the same parameters. For "getprosol" to work, the probe calibration table (the prosol table) must be properly filled in. I haven't used "setprosol", I normally do this with "edprosol" - but this may depend on the software release. I think you system administrator probably needs to fill in this calibration table. You will need calibrations for both observe and decoupling. "wobb" will normally start with the lowest frequency defined for the experiment which will be 19F for PROF19DEC. You can then cycle through the other defined nuclei with a button on the toolbar. The "wobb" trace shouldn't be noisy. If it is still noisy after a proper "getprosol" you may have some hardware issues. Note that you will probably need some filters to do 1H-19F double resonance. You will need a 1H pass 19F stop (or possibly high-pass) on the 1H channel, and a 19F pass (or possibly low-pass) 1H stop on the 19F channel. On a system with a QNP probe, these are normally provided with the system. These filters go between the probe and the pre-amp. We do 1H-19F double resonance all the time. |
By the way, while uploading the picture file, I got this error "sorry, file uploading requires karma >60". So for now, I put it in my dropbox, but I would like to upload it to wiki's server to keep it alive for future. - Amin os (May 04 '12 at 06:24)
I should include that I tried XBB through X100W amplifier, but did not work. But is it correct to use 50W amplifier for both? - Amin os (May 04 '12 at 06:26)