The Raman spectrum of water is weak → the aqueous solution system is suitable for detection and has high sensitivity; the excitation light source generally requires a light source with good monochromaticity → the Raman effect is enhanced

In the Raman spectrum with wave number as the variable, the Stokes lines and anti-Stokes lines are symmetrically distributed on both sides of the Rayleigh scattering line (gaining or losing the energy of one vibrational quantum)

Stokes lines are stronger than anti-Stokes lines

Usually, the Raman shift is taken as the abscissa and the Raman light intensity is taken as the ordinate.

Peak intensity: concentration

Peak position: functional group, structure, stoichiometric analysis

Spectral peak displacement: stress/strain, deformation

Peak ratio: relative concentration

Polarization: crystal orientation

When a beam of photons irradiates the surface of the sample, the photon can be absorbed by the electrons in the atomic orbit of a certain element in the sample, causing the electrons to break away from the atomic nucleus and be emitted from the interior of the atom with a certain kinetic energy, becoming free. The photoelectrons, and the atom itself becomes an excited ion.

XPS is a surface analysis technology. If the vacuum degree is poor, the sample surface is easily covered by residual gas molecules → it is difficult to obtain real information on the sample surface.

Photoelectron energy is weak. If the vacuum degree is poor → photoelectrons are prone to collision with residual gas molecules and lose energy.

Elemental and chemical state analysis

Quantitative analysis

chemical structure analysis

Non-destructive analysis method (sample is not decomposed by X-rays)

Ultra-trace analysis technology (small amount of sample required)

Trace analysis method (high absolute sensitivity) [but high relative sensitivity, can only detect components with more than 0.1% content in the sample]

DSC refers to a technology that controls the temperature changes of a sample and a reference substance according to a certain program, and measures the difference in heat flow input to the two substances as a temperature relationship.

The holder part of the sample and reference material is combined with the heating furnace to form a DSC device through a thermal resistance and a heat soaking block (heat bath). Corresponding to the heating (or cooling) speed, a certain amount of heat is transferred from the bottom of the sample container to the sample and reference material placed in the furnace through thermal conduction. At this time, the heat flow into the sample is proportional to the temperature difference between the heating block and the bracket.

Compared with the sample, the soaking block has a large heat capacity. Therefore, when the sample undergoes thermal changes, it can absorb (compensate) the cooling or heating caused by the thermal changes, thereby maintaining the temperature difference between the sample and the reference. Stablize. Therefore, the heat difference between the sample and the reference material per unit time is proportional to the temperature difference between the two supports. By using a substance with known heat and pre-correcting the relationship between the temperature difference and the heat, the heat of the unknown sample can be measured.

What is measured is the energy difference required to maintain the sample and reference material at the same temperature → the enthalpy change of the reaction sample

excellent:

lack;

Under the same power given to the sample and the reference product, measure the temperature difference between the two ends of the sample and the reference product.

excellent:

Upward (positive value) is the endothermic peak of the sample [melting, decomposition, desorption]

Downward (negative value) is the exothermic peak [crystallization, oxidation, solidification]

The area enclosed by the peaks or valleys in the curve represents the change in heat

Determination of sample enthalpy change

Determination of specific heat capacity of samples