文档介绍：NMR
Nuclear ic Resonance Spectroscopy
Study of the Interaction of Energy and Matter
When energy (ic Radiation) is applied to matter it can be absorbed, cause a chemical change (reaction), or be transmitted.
Spectroscopy
Spectroscopy Types:
Mass Spectrometry (MS) – Hi-Energy Electron Bombardment
Use – Molecular Weight, Presence of Nitrogen, Halogens
Ultraviolet Spectroscopy (UV) – Electronic Energy States
Use – Conjugated Molecules; Carbonyl Group, Nitro Group
Infrared Spectroscopy (IR) – Vibrational Energy States
Use – Functional Groups; Compound Structure
Nuclear ic Resonance Spectroscopy (NMR) – Nuclear Spin States
Use – The number, type, and relative position of protons (Hydrogen nuclei) and Carbon-13 nuclei
The ic Spectrum
Microwave
Infrared
X-Ray
Vacuum
UV
Visible
Near Ultraviolet
Vibrational
Infrared
Nuclear
ic
Resonance
Radio
Frequency
400 nm
200 nm
800 nm
15
1 m
5 m
Blue
Red
Cosmic
&
Ray
nm
3 x 1019 Hz
3 x 1016 Hz
2 x 1013 Hz
10 nm
30 cm
1 x109cm-1
cm-1
10 cm-1
3 cm-1
cm-1
1 mm
Frequency ()
Energy (E)
High
High
Low
Low
Wavelength ()
Short
Long
1 x107cm-1
5 x104cm-1
x104cm-1
x104cm-1
667cm-1
4 x103cm-1
6 x 107 Hz
3 x 108 Hz
x 1015 Hz
1 x 109 Hz
3 x 1011 Hz
x 1014 Hz
Frequency
Wave Number
Wavelength
Mass Spectrometry
High energy electrons anic molecules breaking some or all of the original molecules into fragments.
The process usually removes a single electron to produce a positive ion (cation radical) that can be separated in a ic field on the basis of the mass / charge ratio.
Removal of the single electron produces a charge of +1 for the cation.
Thus, the cation represents the Molecular Weight of the pound or any of the fragments that are produced.
The mass spectrum produced is a plot of relative abundance of the various fragments (positively charged cation radicals) versus the Mass / Charge (M/Z) ratio.
The most intense peak is called the “Base Peak