Questions tagged [nuclear-magnetic-resonance]

For questions about Nuclear Magnetic Resonance

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How specifically does an MRI machine build an image from received radio waves?

Unlike the excellent Wikipedia page on ultrasound imaging, the one on MRI only explains the principle theory behind MRI - that oscillating strong magnetic fields cause water molecules to emit ...
487 views

Decoherence and measurement in NMR

It seems that the Bloch equations, or a suitable generalization thereof, are enough to phenomenologically model the measurement process in NMR. Has anyone attempted a fully quantum mechanical model ...
509 views

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magnetism in NMR spectroscopy

How do electrons reduce the effective magnetic field felt by protons? This is the explanation given to chemical shift, how does it work?
50 views

Nonlinearities arising from linear equations

I have sources that tell me that the Bloch Equations, which describe the magnetization vector in nuclear magnetic resonance, are nonlinear. In vector form, without relaxation, they are:  \partial_t \...
42 views

NMR Chemical shift and the electron distribution

We explain the position of a hydrogen environment as being downfield if it is deshielded by its proximity to an electron withdrawing group. The electrons around the nucleus protect said nucleus from ...
59 views

is alternating field really needed for NMR/ESR?

Consider a two level system - say a single spin-1/2 electron in a magnetic field. To make transition between the spin-split levels the usual advice is to apply an alternating transverse magnetic field ...
510 views

Why do nuclei precess in magnetic fields?

I understand that a classical bar magnet will precess about the axis of an external magnetic field. Whilst researching NMR, I have read that nuclei with half-integer spin which are subject to an ...
14 views

Integration of Bloch equation in magnetic resonance

From Bloch equation we have $$\label{bloch_01} \tag{1} \frac{d M_z}{dt} = \frac{M_0-M_z}{T_1}$$ from there we can integrate and we get \label{bloch_02} \tag{...
35 views

What does it mean that the Cauchy probability distribution is connected to the solution of the differential equations of forced resonance?

I have read this (or something like this) in Wikipedia, and found some modelling of inhomogeneities in magnetic fields in clinical magnetic resonance imaging (MRI) through the Cauchy distribution, ...