Re: [AMMRL] Y89 measurement

 I was about to resp= ond similar to Dave's email stating that getting to low gamma nuclei via 1H (and perhaps 31P) HMBC has been the most successful route we've used.  The combination of polarization enhancement and= T1 savings is very powerful and makes many of our studies viable that otherwise would not have been.  103Rh and 183W are just a couple of other nuclei we've had 1H-X successes with, in addition to 89Y= .

On 8/31/2023 11:49 AM, Vander Velde, David wrote:

1H-89Y HMBC is pretty straightforward and 89Y sits just above 109Ag which is the nominal low frequency limit of many Bruker broadband probes. Setting it up from scratch, you can guess the length of a 89Y pulse by extrapolating from anything which is calibrated nearby assuming the pulse voltage is constant and then the pulse just scales with the gyromagnetic ratio. The simplest version of an HMBC is pretty forgiving (starting from the 1H-15N parameters with no 1 bond couplings suppressed, no filters on the size of the J). That pulse estimate is enough to get started. You can refine the parameters by running arrays of just the first block of the HMBC. If you don't know where they X signal is (a problem especially for something like 195Pt), you can find it quickly with an array of X nucleus carrier frequencies. With the X signal frequency known, the low gamma pulse width can be calibrated with an array. Likewise, if the 1H-X J coupling is not resolved in the 1H, you can find the value that gives the most signal.

Our experience here is limited to a few 89Y organometallics and the 89Y shifts calculated by absolute referencing were bigger than we expected, but that was the outcome. We never saw any 89Y signals by direct observation, very long T1's and low concentration likely weren't helping.

The same approach has worked for some really low gamma nuclei. We have a newer type Bruker iProbe that is rated to reach 109Ag, and that is the lowest frequency it will reach. However we have a previous generation Bruker probe that will go to lower frequencies. It will tune but not quite match the 12.5 MHz frequency for 103Rh, close enough for HMBC. I got an HMBC signal from Rh(acac)3 even though there is no resolved Rh multiple bond coupling in the 1H spectrum. To get this going, we got some valuable help from Brian Andrew at Bruker with putting firmware entries for these wacky nuclei into that probe.

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From: main_at_ammrl.groups.io <main_at_ammrl.groups.io> on behalf= of Craig Grimmer <craig.grimmer_at_gmail.com>
Sent: Thursday, August 31, 2023 5:29 AM
To: main_at_ammrl.groups.io <main_at_ammrl.groups.io>=
Subject: Re: [AMMRL] Y89 measurement

 

Good afternoon Stephen

For 89Y (transmitter frequency 24.5013454) on a 5 mm broadband probe on a "500" magnet, I use a 3 M solution= of Y(NO3)3.6H2O and I get a reasonable signal from 4 scans (transients) with d1 = 720 seconds with pw = 18 us at 150 W.  I've not measured the T1 of this sample but 720 se= conds seemed a reasonable figure based on the information in Brevard & Granger's book that reads "T1 typical = value (s): > 50").  If you're struggling to fin= d a signal from a multi-molar solution, set a wide sweep width to start with, ~1000 ppm.

Kind regards,

Craig.

On Thu, 31 Aug 2023 at 12:58, Clemens Anklin via groups.io <clemens.anklin=bruker.com_at_groups.io= > wrote:

Hi Stephen

make sure you are in the right spot. Multiply your exact TMS frequency in MHz (6 decimals) with 0.04900 198 (source: doi:10.1351/pac200880010059)
That should get you very close to the Y89 frequency.

Clemens

On 8/30/2023 10:38 PM, Stephen M Spain wrote:

**EXTERNAL EMAIL**

Hi,

      One of the PI's wants to measure Y89 on our 500 MHz Varian VNMRS spectrometer. I found an ancient 10 mm low frequency probe that can do 15 to 50 MHz in one our cabinets that I'd never used. I got the probe to tune to the 24 MHz needed for Y89 via mtune but can't observe anything for either the 200 mM or 1 M  yttrium nitrate solutions. <= /span>

  â= €‚   Since I've never done anything this low of a frequency before is there anything besides the quarter wavelength cable that needs to be changed or adjusted on a Varian VNMRS? I saw in the probe manual that a switch needed to be flipped on the pre-amp but I assume that is for an early 1990's console.

 â€= ‚    The probe is probably in need of service since it was here decades before I was, but any suggestions would be greatly appreciated.

thanks,

Stephen

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