What is Raman light and what does Raman spectroscopy do?

Raman effect = light scattering is a light scattering process

Laser energy - vibrational spectrum energy = Raman scattered light energy (vibrational spectrum energy corresponds to molecular structure).

Laser energy - Raman scattered light energy = vibrational spectrum energy (the resulting Raman spectrum is the fingerprint of the molecule).

Laser wavelengths are commonly used in Raman spectroscopy systems.

The advantages and features of Raman spectroscopy, which are components of a Raman spectroscopy system.

fingerprint for qualitative identification Fingerprint vibration spectroscopy.

no sample preparation No sample preparation.

fast and non destructive.

highly selective technique High selective north Why use micro-Raman High spatial resolution; The amount of sample required is small.

Raman scattering spectroscopy applications.

Raman spectroscopy is a vibrational spectroscopy that is directly linked to the molecular structure and can be used to fingerprint a substance. Any slight change in the structure of a substance is very sensitively reflected in Raman spectroscopy, so it can be used to study the physicochemical properties of a substance as a function of structure.

Wide range of applications:

Polymers * Nanomaterials * Electrochemistry * Semiconductors * Thin Films * Mineralogy * Biology * Medical Pharmaceuticals * Carbides * **Process Monitoring * Quality Control.

Forensics: Glass Materials - Oxides - Paints and Pigments - Hydroxides - Polymers - Sulfides - ** - Carbonates - Fibers - Sulfates - Chemical Residues - Phosphates - Particulate Inclusions - Narcotics and Controlled Substances And so on ......

Infrared and Raman.

Red Wai Laman.

Molecular vibrational spectroscopy.

Absorption, direct process, development earlier.

The dipole moment change near the equilibrium position is not zero.

Complementary to Raman spectroscopy.

The experimental instrument is based on an interferometer as a dispersive element.

The test is carried out in the middle and far infrared, which is not interfered with by fluorescence, and it is difficult to test at low wavenumber (far infrared), and it is difficult to test in micro-area, with a spot size of about 10 microns and poor spatial resolution.

Infrared detectors must be noisy, liquid nitrogen cooled, and have low sensitivity.

In most cases, samples must be prepared.

What is the absorption of infrared light by water? Molecular vibrational spectroscopy.

Scattering, an indirect process, has only developed since the laser.

The change in polarizability near the equilibrium position is non-zero.

Complementary to infrared spectroscopy.

The experimental instrument uses the grating as the dispersive element.

Tests are performed in the visible wavelength band, sometimes disturbed by sample fluorescence, and can be excitation in the near infrared.

There is no problem with low wavenumbers, and the confocal microscope is tested, and the spot size can be as small as 1 micron, and the spatial resolution is good.

The CCD detector has low noise, thermoelectric cooling, high sensitivity, no sample preparation, and can be tested at a long distance.

There is no interference from water to the absorption of infrared light.

The peak and g-peak are the Raman characteristic peaks of the C atomic crystal, which are around 1300 cm-1 and 1580 cm-1, respectively. The D-peak represents the defect of the crystal lattice of the C atom, and the G-peak represents the in-plane expansion and contraction vibration of the hybrid Sp2 of the C atom. In addition, the explanation in solid state physics is the phonon vibration mode, which is too difficult to understand, so I won't explain it much here.

i(g) is the ratio of the intensity carried by the d-peak and the g-peak, where i stands for intensity. This ratio can be used to describe the intensity relationship between the two peaks. As mentioned earlier, the D-peak represents the defects in the crystal lattice, so the larger the value, the more defects in the crystal of the C atom.

3.Why do Raman spectroscopy: Because for crystals with pure C elements, it is not possible to use infrared spectroscopy to detect their structure.

Infrared spectroscopy can only have a strong absorption signal for molecules with infrared activity. The so-called infrared activity means that the dipole change is not zero. The more symmetrical the structure, the less the change in the dipole, such as c-c, c=c, c-tric, o-o, n-trin, etc., such homonuclear diatomic pairs are infrared inactive.

As a result, it is difficult to observe the stretching vibrational characteristic peaks of these homonuclear diatomic pairs on infrared discs (if they are to be observed, relatively weak infrared absorption peaks can only be detected unless they are surrounded by asymmetrical groups). However, in general, homonuclear Zenmaoc pairs with weak IR activity will have strong Raman activity, so their Raman peaks can be easily detected on the Raman spectrum. That's why Raman spectroscopy was done.

Raman spectra is a type of scattering spectrum. Raman spectroscopy is an analytical method based on the Raman scattering effect discovered by Indian scientist Raman to analyze the scattering spectrum different from the incident light frequency to obtain information on molecular vibration and rotation, and is applied to the study of molecular structure.

Raman is an Indian physicist. He was awarded the Nobel Prize in Physics in 1930 for his research work on light scattering and the discovery of the Raman effect.

Hashem Raman, male, born on November 7, 1972 in Baltimore, Maryland, USA, American boxer, nicknamed Rock, Rahman is a star who has been active in heavyweight boxing since 2000. Since knocking out Lewis in South Africa in 2001, Rahman has become famous overnight and his value has begun to double. In the rematch with Lewis, the appearance fee jumped to more than $10 million.

Unfortunately, it took only four rounds for Lewis to clean up. The three belts that Raman received in April of that year were returned to Lewis in November of that year. The encounter is somewhat similar to Douglas, who became an overnight sensation by knocking out Tyson more than a decade ago, becoming a short-lived heavyweight champion.