NMR Chemical Shift

<p>It is a reference compound (B)</p> Signup and view all the answers

<p>They correspond to the carbon atoms in the molecule (D)</p> Signup and view all the answers

<p>Angular momentum or spin (D)</p> Signup and view all the answers

<p>It can either partially cancel or partially augment the applied field (C)</p> Signup and view all the answers

<p>Because of differences in the local magnetic field experienced by each nucleus (B)</p> Signup and view all the answers

<p>The frequency of the signal versus the intensity of the signal (A)</p> Signup and view all the answers

<p>Because it is proportional to the strength of the applied magnetic field (B)</p> Signup and view all the answers

<p>To allow for comparison of results from different instruments (B)</p> Signup and view all the answers

<p>They double (B)</p> Signup and view all the answers

<p>Because of slight drifting of the magnetic field (C)</p> Signup and view all the answers

<p>To allow multiple scans to be added together (B)</p> Signup and view all the answers

<p>The entire desired frequency range (B)</p> Signup and view all the answers

<p>The NMR spectrum (A)</p> Signup and view all the answers

<p>To allow the nuclei to relax back to the ground state (C)</p> Signup and view all the answers

<p>Relaxed back to the ground state (D)</p> Signup and view all the answers

The solvent peak in a 13C coupled NMR spectrum is irrelevant and can be ignored. For example, chloroform (CDCl3) has a triplet peak at ~77 ppm.

A data output presented visually. It provides information about the chemical structure of a molecule by analyzing the magnetic properties of its nuclei.

Units of chemical shift on the x-axis of an NMR spectrum, ranging from ~0-200 ppm for carbon atoms.

A known chemical compound used as a reference point in NMR, assigned a chemical shift of 0 ppm.

The location of a signal in an NMR spectrum, determined by the local magnetic environment of a specific nucleus.

Nuclei of certain elements have an intrinsic spin, making them observable in NMR spectroscopy.

The process where nuclei absorb energy in the radiofrequency range, transitioning from a lower energy state (ground state) to a higher energy state (excited state).

Electron clouds surrounding specific nuclei create local magnetic fields that affect the applied magnetic field in NMR.

The phenomenon where electron clouds partially cancel the applied magnetic field experienced by a nucleus, shifting its signal upfield (towards 0 ppm) in the NMR spectrum.

The phenomenon where electron clouds partially augment the applied magnetic field experienced by a nucleus, shifting its signal downfield (towards higher ppm) in the NMR spectrum.

The difference in frequency (in kHz) between the irradiating frequency and the resonant frequency of a specific nucleus.

A relative scale used to display chemical shifts in NMR spectra, eliminating dependence on magnetic field strength.

A reference compound used for standardizing chemical shift values by setting its value to 0 ppm on the chemical shift scale.

A modern type of NMR spectrometer that uses a pulsed radiofrequency excitation and Fourier Transform analysis to generate NMR spectra.

A technique used in FT NMR spectrometers to improve signal quality and reduce noise by averaging multiple scans (data points).

A short, powerful radiofrequency pulse used in FT NMR to simultaneously excite all nuclei in a sample.

The signal that decays after a radiofrequency pulse is applied, containing frequency differences for all nuclei in a sample.

A mathematical process that converts the FID signal into a traditional NMR spectrum by separating different frequency components.

The time required for a nucleus to fully relax back to its ground state after excitation.