[fabian2k]

Benchtops are at 60-90 MHz field strengths. That is not really enough to look at more complex molecules, the bigger routine NMR spectrometers are at 400-600 MHz (and there are even larger ones, but those are not used for small molecules that much). And even then those benchtops cost something close to 100k USD, that's quite far from affordable.

The "room temperature" superconductors are not used at room temperature in these cases, they're still cooled down. And so far the only spectrometer I know of where they are used is the still extremely new 1.2 GHz Bruker. And that one is almost certainly somewhere between 10 and 20 million USD. The new superconductors are low temperature superconductors, not room temperature. And even then they still work better at lower temperatures. At best you can remove the liquid helium from the system and use liquid nitrogen only, which is an advantage but still really far from room temperature.

[kragen]

Thank you for explaining!

Yes, I don't know if the current room-temperature superconductor material (which really is room temperature, 15°C) will ever be useful for this; it was only discovered in 02020, so it is very unlikely that anyone is using it in a product today, even if they find a way to apply the necessary pressure (267 GPa, thus requiring ultrahard anvils). You're probably thinking of something like YBCO, which is "high-temperature" in the sense you're describing, requiring only LN₂, not "room-temperature".

Costs change over time. There was a time when solar panels cost 100k USD, too. A lot of the costs you're describing are NRE; others are costs that can be reduced.

[fabian2k]

The new spectrometers are using YBCO, and they are many years beyond schedule. That whole thing turned out to be a lot harder than many people seemed to expect.

The magnets are not the only cost in NMR spectrometers, I think you're seriously understimating the amount of electronics in them. You need to detect very weak signals at several hundreds of MHz, that's not trivial.

[kragen]

How weak are they? Detecting very weak signals (-110 dBm) at hundreds of MHz and even GHz is routinely done by Wi-Fi cards and cellphone radios, and GPS receivers detect signals that are orders of magnitude weaker than that (routinely -150 dBm), but only at tens of MHz. My eyes routinely detect submillilux signals when I look at the stars at night, with an integration time of well under a second; if I'm doing the calculations correctly, that's about -70 or -80 dBm in the 100–1000 THz band. PMTs (including microchannel plates) and SPADs routinely detect optical signals much weaker than that.

To a significant extent you can detect arbitrarily weak signals with coding gain and longer averaging times, although if your benchtop machine already takes ten minutes to give you a result, you probably can't afford to wait more than about 36 dB longer, give you another 18 dB of SNR).

So, I'm not worried about the electronics or the signal processing; there's no such thing as an "amount of electronics". Precision analog equipment is not easy to design, calibrate, and build, but you only need a very small "amount" of it, and it can be mass-produced.

Take resistors. When I was a kid back in the 01980s normal resistors were ±20% carbon composition, which would drift by more than 20% over time or if overvolted, with fiendish temperature coefficients. Now you can't buy a ±20% resistor; most resistors are ±1%, ±0.1% resistors are commonplace, and ±0.01% resistors are easily available for a dollar or two. Precision resistors are now made with an extremum of resistance around room temperature, so the temperature coefficient there is literally zero.

No, what I'm worried about is the physics. I'm not surprised YBCO spectrometers turned out to be a pain in the ass; YBCO is a huge pain in the ass in every possible way. What do you think the physical obstacles are?

[dekhn]

The signals are weak, but more importantly, the signals are being detected in a volume wiht a huge magnetic field. You can't even put a digital circuit anywhere in the amplifier. When I worked on the NMR all the monitors in the room were shifted toward the magnet, it would wipe your credit cards, and to adjust the amplifier involved sitting under a multi-ton device twiddling knobs to minimize the impedence.

Think of NMR as bespoke. Like a large luxury liner built for a rich individual. It's not ever going to be a zodiac.

[kragen]

As I understand it, the magnetic field doesn't have to be voluminous; it just has to be strong and uniform. It can be arbitrarily small as long as it's large compared to an atom, which is why benchtop NMR machines can exist at all, though they won't ever be truly miniature unless either we can also miniaturize the cryostats and refrigerant supply, or we can find a usable room-temperature superconductor. Am I misunderstanding something? As I said, you know a lot more about this than I do.

[dekhn]

NMR is an ensemble measurement technique. You can't measure the magnetic moment of a single molecule. Instead, you need a highly pure sample and lots of it. That has to be in solvent (I'm leaving out solid spinning NMR here, that's a different ballgame entirely), enough solvent to keep the sample in solution.

I think you're wasting your time trying to improve NMR. The value of the technique isn't worth it.