Chapter 13
Molecular Vibrational Spectroscopy
Spectroscopie infrarouge (IR) : Vue d’ensemble
When electromagnetic radiation passes through a material, atoms or molecules transition from a lower to a higher energy state by absorbing radiation ...
Spectroscopie IR : aperçu des vibrations moléculaires
When Infrared (IR) radiation passes through a covalently bonded molecule, the bonds transition from lower to higher vibrational levels. The fundamental ...
Spectroscopie IR : approximation de la vibration moléculaire selon la loi de Hooke
A covalently bonded heteronuclear diatomic molecule can be modeled as two vibrating masses connected by a spring. The vibrational frequency of the bond ...
Spectromètres IR
There are two main infrared (IR) spectrophotometers: dispersive IR spectrometers and Fourier transform infrared (FTIR) spectrometers. In a dispersive IR ...
Spectre IR
When infrared (IR) radiation passes through a molecule, the bonds stretch or bend by absorbing the radiation. This absorption creates the molecule's ...
Fréquence d’absorption IR : Hybridation
Hydrocarbons such as alkanes, alkenes, and alkynes show characteristic C–H stretching absorption bands. These IR stretching frequencies depend on ...
Fréquence d’absorption IR : délocalisation
Electron delocalization refers to the distribution of electrons across multiple atoms within a molecule rather than being confined to a single atom or ...
Région de fréquence IR : Étirement X-H
In IR spectroscopy, signals produced by the X−H bonds (such as C−H, O−H, or N−H) can be observed in the frequency range of ...
Région de fréquence IR : Étirement de l’alcyne et du nitrile
Both alkyne (C≡C) and nitrile (C≡N) functional groups contain triple bonds and show stretching absorptions around the wavenumber range of 2100 ...
Région de fréquence IR : Étirement des alcènes et des carbonyles
Double bonds in alkenes and carbonyl compounds exhibit stretching frequencies in the diagnostic region of the IR spectrum. In addition, alkenes exhibit ...
Région de fréquence IR : Région d’empreinte digitale
IR spectra are divided into two main regions: the diagnostic region and the fingerprint region. The diagnostic region of the spectrum lies above 1500 ...
Intensité maximale du spectre IR : Quantité d’obligations actives IR
When infrared radiation is passed through a molecule, absorption occurs if the molecule's vibration leads to a substantial change in its bond dipole ...
Intensité de crête du spectre IR : moment dipolaire
The dipole moment of a bond is the product of the partial charge on either atom and the distance between them. Dipole moments influence the efficiency of ...
Élargissement du pic du spectre IR : liaison hydrogène
The vibrational frequency of a bond is directly proportional to its bond strength. As a result, stronger bonds vibrate at higher frequencies, while weaker ...
Fractionnement des crêtes du spectre IR : vibrations symétriques ou asymétriques
Identical bonds within a polyatomic group can stretch symmetrically (in-phase) or asymmetrically (out-of-phase). Similar to hydrogen bonding, these ...
Applications de la spectroscopie IR : aperçu
The non-destructive nature and ability to provide valuable chemical information make IR spectroscopy a versatile technique with broad applications in ...
Spectroscopie infrarouge à réflectance totale atténuée (ATR) : vue d’ensemble
Attenuated total reflectance (ATR) infrared spectroscopy is a powerful analytical technique used to study the composition of materials. It is widely ...
Spectroscopie Raman : Vue d’ensemble
The underlying principle of Raman spectroscopy is based on the interaction between light and matter, specifically molecules' inelastic scattering of ...
Instrumentation de spectroscopie Raman : Vue d’ensemble
A conventional Raman spectrophotometer includes a laser source, a sample holding system, a wavelength selector, and a detector.
The monochromatic laser ...
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