Glossary
Artifact
A feature which appears in an NMR spectrum of a molecule which should not be present based on the chemical structure and pulse sequence used. [Chapter 7]
Chemical Screening
The screening of an applied magnetic field experienced by a nucleus due to the electron cloud around an atom or molecule. [Chapter 4]
Chemical Shift
A variation in the resonance frequency of a nuclear spin due to the chemical environment around the nucleus. Chemical shift is reported in ppm. [Chapter 4]
Coil
One or more loops of a conductor used to create a magnetic field. In NMR, the term generally refers to the radiofrequency coil. [Chapter 7]
Convolution
A mathematical operation between two functions. [Chapter 2]
Complex Data
Numerical data with a real and an imaginary component. [Chapter 2]
Continuous Wave (CW)
A form of spectroscopy in which a constant amplitude electromagnetic wave is applied. [Chapter 3]
Coordinate Transformation
A change in the axes used to represent some spatial quantity. [Chapter 2]
Cryopumping
The condensation of air onto a surface cooled by a cryogenic liquid . [Chapter 8]
Dephasing Gradient
A magnetic field gradient used to dephase transverse magnetization. [Chapter 11]
Digital Filtering
A feature found on may newer spectrometers which eliminates wraparound artifacts by filtering out the higher frequency components in the time domain spectrum. [Chapter 7]
Doubly balanced mixer
An electrical device, often referred to as a product detector, which is used in NMR to convert signals from the laboratory frame of reference to the rotating frame of reference. [Chapter 7]
Echo
A form of magnetic resonance signal from the refocusing of transverse magnetization. [Chapter 6]
Echo Time ( TE )
The time between the 90 degree pulse and the maximum in the echo in a spinecho sequence. [Chapter 6]
Exchange, Chemical
The interchange of chemically equivalent components on a molecule. [Chapter 3]
Exchange, Spin
The interchange of spin state between two nuclei. [Chapter 3]
Figure8 Coil
A magnetic field gradient coil shaped like the number eight. [Chapter 7]
Free induction decay ( FID )
A form of magnetic resonance signal from the decay of transverse magnetization. [Chapter 4]
Fourier transform ( FT )
A mathematical technique capable of converting a time domain signal to a frequency domain signal and vice versa. [Chapter 5]
Gradient ( G )
A variation in some quantity with respect to another. In the context of NMR, a magnetic field gradient is a variation in the magnetic field with respect to distance. [Chapter 7]
Gyromagnetic Ratio
The ratio of the resonance frequency to the magnetic field strength for a given nucleus. [Chapter 3]
Imaginary Component
The component of a signal perpendicular to the real signal. [Chapter 5]
Imaging Sequence
A specific set of RF pulses and magnetic field gradients used to produce an image. [Chapter 11]
Inversion Recovery Sequence
A pulse sequence producing signals which represent the longitudinal magnetization present after the application of a 180^{o} inversion RF pulse. [Chapter 6
Inversion Time (TI)
The time between the inversion pulse and the sampling pulse(s) in an inversion recovery sequence. [Chapter 6]
KSpace
That image space represented by the time and phase raw data. The Fourier transform of kspace is the magnetic resonance image. [Chapter 5]
Larmor frequency
The resonance frequency of a spin in a magnetic field. The rate of precession of a spin packet in a magnetic field. The frequency which will cause a transition between the two spin energy levels of a nucleus. [Chapter 3]
Longitudinal Magnetization
The Z component of magnetization. [Chapter 3]
Lorentzian Lineshape
A function obtained from the Fourier transform of an exponential function. [Chapter 5]
Magnitude
The length of a magnetization vector. In NMR, the square root of the sum of the squares of the Mx and My components, i.e. the magnitude of the transverse magnetization. [Chapter 2]
Magnetic Resonance Imaging (MRI)
An imaging technique based on the principles of NMR. [Chapter 11]
Negative Frequency Artifact
The appearance of smaller in amplitude peaks in one half of the spectrum which are the mirror image of ones in the opposite half. [Chapter 8]
Net Magnetization Vector
A vector representing the sum of the magnetization from a spin system. [Chapter 3]
Nuclear Magnetic Resonance (NMR)
A spectroscopic technique used by scientists to elucidate chemical structure and molecular dynamics. [Chapter 1]
Pixel
Picture element. [Chapter 1]
Precess
A rotational motion of a vector about the axis of a coordinate system where the polar angle is fixed and the azmuthal angle changes steadily. [Chapter 3]
Proportionality Constant
A constant used to convert one set of units to another. [Chapter 8]
Pulse Sequence
A series of RF pulses and/or magnetic field gradients applied to a spin system to produce a signal whose behavior gives information about some property of the spin system. [Chapter 4]
Quadrature Detection
Detection of Mx and My simultaneously as a function of time. [Chapter 9]
Radio Frequency
A frequency band in the electromagnetic spectrum with frequencies in the millons of cycles per second. [Chapter 3]
Raw data
The Mx and My data as a function of time and/or other parameters in an NMR pulse sequence. This is also called kspace data. [Chapter 10]
Real
The component of a signal perpendicular to the imaginary signal. [Chapter 2]
Repetition Time
The time between repetitions of the basic sequence in a pulse sequence. [Chapter 6]
Resonance
An exchange of energy between two systems at a specific frequency. [Chapter 3]
RF Coil
An inductorcapacitor resonant circuit used to set up B_{1} magnetic fields in the sample and to detect the signal from the sample. [Chapter 7]
RF Pulse
A short burst of RF energy which has a specific shape.
Rotation Matrix
A matrix used to describe the rotation of a vector. [Chapter 3]
Sample Probe
That portion of the NMR spectrometer containing the RF coils and into which the sample is placed. [Chapter 7]
Saddle Coil
A coil geometry which has two loops of a conductor wrapped around opposite sides of a cylinder. [RF: Chapter 7]
Spin
A fundamental property of matter responsible for NMR and MRI. [Chapter 3]
Spin Density
The concentration of spins. [Chapter 6]
SpinEcho
An NMR sequence whose signal is an echo resulting from the refocusing of magnetization after the application of 90^{o} and 180^{o} RF pulses. [Chapter 6]
SpinLattice Relaxation
The return of the longitudinal magnitization to its equilibrium value along the +Z axis. [Chapter 3]
SpinLattice Relaxation Time ( T_{1} )
The time to reduce the difference between the longitudinal magnitization and its equilibrium value by a factor of e. [Chapter 3]
Spin Packet
A group of spins experiencing the same magnetic field. [Chapter 3]
SpinSpin Relaxation
The return of the transverse magnitization to its equilibrium value (zero). [Chapter 3]
SpinSpin Relaxation Time
The time to reduce the transverse magnetization by a factor of e. [Chapter 3]
Sinc Pulse
An RF pulse shaped like Sin(x)/x. [Chapter 5]
Superconduct
To have no resistance. A perfect superconductor can carry an electrical current without losses. [Chapter 7]
T_{2}*
Pronounced T2star. The spinspin relaxation time composed of contributions from molecular interactions and inhomogeneities in the magnetic field. [Chapter 3]
Timing Diagram
A multiaxis plot of some aspects of a pulse sequence as a function of time. [Chapter 6]
Transverse magnetization
The XY component of the net magnetization. [Chapter 3]
