Hello Again AMMRL List-
What a great resource this is - I got at least 50 responses to my query - too many to acknowledge everyone. Please know that you are all very much appreciated.
Getting onto the summary:
> 1. Can the probe be used without cooling? If there is no cooling, is it basically like a rt probe?
No, the probe cannot be used without cooling. The probes are designed to operate cold and many things change (e.g. magnetic susceptibilities) with temperature making operation at higher temperatures impossible.
> 2. If the probe is not used for long periods - presumably a rt multinuclear probe would be in place most of the time - does that cause problems when it is used? I guess another way to put it would be whether taking it in and out of the magnet multiple times seems reasonable?
Cryoprobes can be swapped in and out. However, it is not an operation that can be done in the same way rt probes are swapped. N2 cryoprobes are easier to swap than He cryoprobes, but still non-trivial; requiring vacuum pumping and temperature equilibration. Most installations leave them in the magnet continuously, or at least for long periods.
>
> 3. My assumption is that no special nmr tubes are used for a cryoprobe - let me know if this is not the case.
My assumption was correct - standard NMR tubes appear to work fine.
Several respondents added information regarding service and maintenance (more costly than a rt probe) and also the S/N enhancement they see - which is considerable, and VT range, which is reduced compared with a rt probe.
It is obviously to me that - even with the S/N advantages of a cryoprobe - there are some negating factors at a small undergraduate institution such as this. I am not sure of the correct path forward right now, but this information really helps us to find what is best for this University.
Thank you all again.
Tom Pratum
Southern Oregon University
> On Sep 19, 2019, at 8:58 PM, Tom Pratum <tkp9551_at_gmail.com> wrote:
>
> Hello AMMRL List-
> We are currently pursuing funding for a new instrument. One question has come up regarding whether it is worth purchasing a cryoprobe. This instrument is used for a lot of routine/undergrad teaching and research. I am wondering about a couple of questions regarding a nitrogen cooled probe:
>
> 1. Can the probe be used without cooling? If there is no cooling, is it basically like a rt probe?
>
> 2. If the probe is not used for long periods - presumably a rt multinuclear probe would be in place most of the time - does that cause problems when it is used? I guess another way to put it would be whether taking it in and out of the magnet multiple times seems reasonable?
>
> 3. My assumption is that no special nmr tubes are used for a cryoprobe - let me know if this is not the case.
>
>
> Thanks very much in advance for any responses!
>
>
> Tom Pratum
> Southern Oregon University
Received on Sun Sep 22 2019 - 11:58:06 MST