Nuclear Magnetic Resonance Spectroscopy NMR Why NMR The

Nuclear Magnetic Resonance Spectroscopy (NMR)

Why NMR? �The most powerful and broadly applicable technique for structure determination �Provides the most information about molecular structure � 1 H NMR and 13 C NMR are the most common

NMR in Peer Reviewed Papers

What is NMR? �Applying an external magnetic field

How is the External Magnetic Field Created? �It is created by a superconducting electromagnet

�The NMR magnet is a coiled wire �Made of nobium and tin/titanium �Lots of current is running through it

Your sample is placed in the middle of a magnetic field �The lower the resistivity the higher the current �The higher the current the stronger the magnetic field

How do we achieve low resistivity? �The wire needs to be at supercritical temperature �This is extremely cold �If the wire goes below its supercritical temperature it has 0 resistivity

Nobium �Niobium makes for a terrific superconductor �It has a high critical temperature compared to other elements on the periodic table at 9. 25 K

�That means at that temperature its resistivity is exactly zero �It can handle lots of current to increase magnetic field strength � Nb is bonded with tin or titanium (to make Nb 3 Sn or Nb. Ti wire) to increase durability

Liquid Helium �The magnet sits in the coldest substance on the planet �Liquid Helium is 4 K �Liquid Nitrogen (77 K) keeps this cold �The air conditioner (65 °C) keeps the LN 2 cold

Safety Rules �Do not turn off the air conditioner �Wear a sweat shirt �If He rapidly boils it will throw the magnet off center �This is a QUENCH! �QUENCH = BAD �A quench repair on average is $18, 000 �Cost of NMR $350, 000 - $800, 000

NMR Probe � It’s “pulse” NMR because the console generates RF pulses orthogonally to the magnetic field � The probe delivers and receives them to produce a signal � Tune properly. . but be careful with Tune and Match Rods (use red non-magnetic tool to turn) http: //www. analyticalspectroscopy. net/

Let’s run a sample �https: //youtu. be/B_NWbc. DVh. Mk

Quick Tips to Preserve Probe �Use the spacer tool �LFG - LISTEN FOR GAS when sample is at top of bore �Document all error messages �Try “ii restart” if you can’t wobb or lock �Try another “getprosol” if you can’t wobb or lock �If it’s not the machine it’s probably your sample (Is it the solvent? Is it fresh? Is the sample at optimal concentration? )

Quality Control �Prevention is the best medicine �Refurbished probe �New Console �New Software �Record error messages (led to updated firmware) �Write name on schedule �If you see something say something (24/7)

Quick Tips on NMR Tubes � Wilmad 528 -pp, 8 inch � Putting in oven too long can…. . � …. warp the glass

THINK: What can the NMR do for YOU?