Welcome to the Low Field NMR facility in the Department of Chemistry and Chemical Biology. The Chemistry NMR Facility is dedicated to research on small molecules in organic-, inorganic-, and bio- chemistry areas and is open to all researchers at Rutgers and neigboring region companies. The facility house four NMR spectrometers: 500MHz, 400MHz, and 300MHz VNMRS liquids spectrometers and a 400MHz Bruker AVANCE III solid-state NMR spectrometer.
What is NMR?
NMR – Nuclear Magnetic Resonance is a branch of spectroscopy (spectroscopy: study of matter interacting with electromagnetic radiation) that deals with the phenomenon found in assemblies of large number of nuclei of atoms possessing both “magnetic moments” and “angular momentum” subjected to external magnetic field.
Resonance – Implies that we are in tune with a natural frequency of the nuclear magnetic system in the magnetic field. Typically, the NMR frequencies fall in the radio frequency range of the electromagnetic radiation spectrum.
The nucleus of many atoms behaves like a tiny bar magnet – we say the nucleus possesses a magnetic moment μ. The magnetic moment arises from a fundamental property of the nucleus known as spin which gives rise to an angular momentum I and given as μ = γ(h/2π)I, wherein h is the Plank’s constant, and γ is the gyromagnetic ratio.
The interaction of nuclear magnetic moment μ with external magnetic field B0, known as Zeeman interaction (E = -μ . B0). Taking the direction of the applied magnetic field along the Z- axis,
E = -μ . B0 = -γ(h/2π)I . B0 = -γ(h/2π)IzB0 = -γ(h/2π)B0mI = -hνmI, where mI is the azimuthal quantum number going from –I to +I in steps of one and ν = γ(h/2π)B0.
The Zeeman interaction energy is proportional to the strength of the applied magnetic field and the magnetic moment. If we set I=1/2, there can be a transition between the mI = +1/2 to mI = -1/2 states, which is at the Zeeman energy E = hν and gives rise to the NMR signal when the system is perturbed at the right frequency ν (resonance).
The hydrogen nucleus (proton) possesses the largest magnetic moment of all the stable isotopes that have non-zero magnetic moments and has a resonance frequency of 2 kHz at the earth magnetic field. This will give an appreciation for the strength of the typical magnetic fields used in NMR, wherein proton resonance frequencies range from 300 MHz to 1000 MHz (1 GHz).
To understand more about NMR, please check the NMR course page.
Department of Chemistry and Chemical Biology
Rutgers, The State University of New Jersey
610 Taylor Road
Piscataway, NJ 08854-8066