Vibrational Spectrum
Vibrational Spectrum - Related Videos
01:08
IR Spectrum Peak Splitting: Symmetric vs Asymmetric Vibrations
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2024
Identical bonds within a polyatomic group can stretch symmetrically (in-phase) or asymmetrically (out-of-phase). Similar to hydrogen bonding, these vibrations also influence the shape of the IR peak. Generally, asymmetric stretching frequencies are higher than symmetric stretching frequencies. For example, primary amines exhibit two distinct IR peaks between 3300–3500 cm−1 corresponding to the symmetric and asymmetric N-H stretching, while secondary amines exhibit a single stretching vibration...
02:37
The Electromagnetic Spectrum
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2020
The electromagnetic spectrum consists of all the types of electromagnetic radiation arranged according to their frequency and wavelength. Each of the various colors of visible light has specific frequencies and wavelengths associated with them, and you can see that visible light makes up only a small portion of the electromagnetic spectrum. Because the technologies developed to work in various parts of the electromagnetic spectrum are different, for reasons of convenience and historical...
07:28
Measurement of Bioelectric Current with a Vibrating Probe
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Cited by 15 •
2011
The manufacture, calibration and use of non-invasive vibrating probes to measure bioelectric current in various biological systems is described.
01:19
IR Spectrum
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2024
When infrared (IR) radiation passes through a molecule, the bonds stretch or bend by absorbing the radiation. This absorption creates the molecule's absorption spectrum, which is the plot of its percentage transmittance versus wavenumber. Transmittance is defined as the ratio of the radiant power passing through a sample to that from the radiation's source. Multiplying the transmittance by 100 gives the percent transmittance (%T), which varies between 100% (no absorption) and 0% (complete...
01:19
Vibrating Concrete
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2024
Mechanical vibrators are instrumental in compacting newly poured concrete within formwork and around reinforcements. This process is essential to eliminate trapped air pockets and establish a dense concrete mass. One widely used method is vibrating by internal vibrators, often referred to as a poker vibrator or immersion vibrator. It is rapidly inserted through the full depth of the freshly laid concrete and slightly extends into the layer below it (which remains in a plastic state). Consistent...
FAQs
Infrared measurements respond to vibrational motions that change a molecule’s dipole moment, whereas Raman measurements reveal motions that change polarizability, meaning how the electron distribution responds to electromagnetic radiation. Because these properties differ, the two methods can emphasize different modes of the same molecule. Using both approaches can strengthen structural identification and provide a more complete view of bonding and symmetry.
A bond’s vibrational frequency reflects its chemical environment and the type of motion it undergoes, including stretching or bending. Changes in bonding, molecular interactions, or surrounding structure can therefore alter spectral features. Chemists interpret these frequency patterns alongside molecular structure to distinguish compounds, examine local environments, and connect observed signals with particular chemical changes.
Molecular symmetry helps determine how vibrational motions interact with infrared radiation or Raman scattering. A mode’s symmetry is related to whether it changes dipole moment, polarizability, or both, which affects its spectral visibility. Considering symmetry prevents chemists from treating every possible bond motion as equally observable and supports more reliable assignments of features to molecular structure.
Analysis begins by examining the overall pattern of spectral features rather than relying on a single signal. Chemists relate those features to stretching, bending, bonding, symmetry, and local chemical environments, then compare the resulting pattern with the expected behavior of candidate substances. This approach helps identify compounds, distinguish closely related materials, and assess whether the observed composition matches expectations.
During a reaction, changes in spectral features can indicate that bonding or molecular environments are changing. Chemists track the spectrum as the reaction proceeds and interpret the evolving pattern in terms of stretching, bending, and other vibrational modes. This provides information about changing composition and can help investigate reaction mechanisms by linking spectral changes to chemical transformations.
Spectral features can reveal how molecular structure, bonding, symmetry, and local chemical environments are organized within a material or interaction system. Comparing patterns across samples can expose compositional differences or changes caused by molecular interactions. Consequently, vibrational spectroscopy supports chemical studies that extend beyond identification, including examinations of materials behavior and the molecular basis of interactions.