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16 methods of material analysis demonstrated by Gif

Time:2019/12/17 丨 source:web 丨 visit count:

16 methods of material analysis demonstrated by Gif


Contents
 1. Ultraviolet spectrophotometry UV   2. Infrared spectroscopy IR
 3. NMR spectroscopy  4. Mass Spectrometry MS
 5. Gas Chromatography GC  6. Gel Permeation Chromatography GPC
 7. Thermogravimetry TG   8. Thermal-Mechanical Analysis TMA
 9. Transmission Electron Microscopy TEM 10. Scanning Electron Microscopy SEM
11. Atomic Force Microscopy AFM 12. Scanning Tunneling Microscope STM
13. Atomic Absorption Spectroscopy AAS 14. Inductively Coupled Plasma ICP
15. XRD 16. Nanoparticle Tracking Characterization
 

1. Ultraviolet spectrophotometry UV 

Principle of analysis: The absorption of ultraviolet energy, causing the transition of electronic energy levels in molecules
Spectrogram representation: The change of the relative absorption energy with the wavelength of the absorption light
Information provided: The position, strength, and shape of the absorption peaks provide information about the different electronic structures in the molecule
When a material molecule absorbs ultraviolet light of a certain wavelength, the absorption spectrum produced by the transition of Valence electrons from low energy level to high energy level is higher than that of ultraviolet spectrum. Violet absorption spectroscopy is mainly used to determine conjugated molecules, components and equilibrium constants.

Light Transmission
light diffraction
Detection

Data Output

2. Infrared spectroscopy IR

Principle of analysis: Absorption of infrared light energy, causing the change of molecular dipole moment vibration, rotational energy level transition 
Spectrogram representation: The relative transmitted light energy varies with the transmitted light frequency 
Information provided: The location, strength, and shape of the peaks, providing the characteristic vibrational frequencies of functional groups or chemical bonds.


Infrared spectroscopy

The characteristic absorption peaks of the infrared spectra correspond to the molecular groups, and thus the structural formula can be inferred from the infrared spectra.
The following is the infrared spectrum analysis process of methanol






Structural analysis of methanol by infrared spectroscopy

3. NMR Spectroscopy

Principle of analysis: In the external magnetic field, nuclear with nuclear magnetic moment, absorption of radio-frequency energy, nuclear spin level of the transition 
Spectrogram representation: The change of absorbed light energy with chemical shift 
Information provided: Chemical Shifts, intensities, fission numbers, and coupling constants of the peaks provide information on the number, chemical environment, and geometry of the Nuclei


NMR structure

Inject

Sample in the magnetic field

The energy of the radio-frequency field can be effectively absorbed when the frequency of the external radio-frequency field is the same as that of the spin precession of the nucleus Can only absorb the energy provided by the radio frequency field of a certain frequency, thus forming the nuclear magnetic resonance signal.




Nuclear magnetic resonance and data output
 

4. Mass Spectrometry MS

Principle of analysis: Molecules are bombarded by electrons in a vacuum to form ions, which vary by M / e through an electromagnetic field 
Information provided: Mass number and relative Kurtosis of Molecular and fragment ions, providing information on molecular weight, elemental composition and structure 
FT-ICR  Mass Spectrometer Process:


Iron Production

Iron Collection

Iron transport

The analyzer of FT-ICR mass spectrometry is a cavity with a uniform superconducting magnetic field. The Cyclotron motion of the ions in a circular orbit perpendicular to the magnetic field is only related to the magnetic field intensity and the mass-charge ratio of the ions Therefore, ions with different mass-charge ratios can be separated and mass-charge ratio related spectra can be obtained.




Ion cyclotron motion

Fourier transform

5. Gas Chromatography GC

Principle of analysis: The components in the sample are separated between the mobile phase and the stationary phase due to different partition coefficients 
Spectrogram representation: The change of concentration of effluent after column with retention value 
Information provided: The retention value of the peak is related to the thermodynamic parameters of the components and is the qualitative basis

GAS CHROMATOGRAPH test procedure:
Gas chromatograph mainly consists of three parts: carrier gas, chromatographic column and detector. The detailed workflow of each module is as follows.


Ingector

Chromatographic Column

Detector

6. Gel Permeation Chromatography GPC

Principle of analysis: When the sample passes through the GEL column, it is separated according to the volume of the molecular fluid mechanics, and the macromolecule flows out first 
Spectrogram representation: The change of concentration of effluent after column with retention value 
Information provided: average molecular weight and distribution of polymers 
The Gel filtration chromatography (GFC) using aqueous solution and Gel permeation chromatography (GPC) using organic solvents can be divided according to the properties of the GEL.

According to the size of separation, large components were first proposed
The chromatographic stationary phase is a porous GEL, and only components with a diameter less than the pore diameter can enter the GEL channel. Large components can not enter the gel hole and be blocked, only through the gap between the GEL particles through, so the largest components were first washed out.


Components smaller than the pore diameter enter the GEL channel
Small fractions can enter most of the GEL voids, remain in the column for a long time, and are washed out more slowly. The solvent molecule is finally eluted from the column because it can enter all the GEL voids because of its minimum volume. This is also the biggest difference with other chromatography.

The components of the sample are separated according to the size difference

Volumetric exclusion chromatography is suitable for the exploratory separation of unknown samples. Gel Filtration Chromatography (GFC) is suitable for the analysis of peptides, proteins, enzymes and other biomolecules in aqueous solution GPC is mainly used to determine the molecular weight of high polymers such as polyethylene, polypropylene, polystyrene, polyvinyl chloride and poly(methyl methacrylate) .


7. Thermogravimetry TG

Principle of analysis: In temperature controlled environment, sample weight changes with temperature or time
Spectrogram representation: Curve of the weight fraction of a sample as a function of temperature or time
Information provided: The precipitous drop of the curve is the weightlessness region of the sample, and the platform region is the thermal stability region of the sample

Automatic injection process



Thermogravimetric analysis process

8. Thermal-Mechanical Analysis TMA

Principle of analysis: The deformation of the sample under the action of constant force varies with temperature or time
Spectrogram representation: sample deformation value with temperature or time change curve
Information provided: Thermal transition temperature and mechanical state

 


TMA sampling and analysis


 9. Transmission Electron Microscopy TEM

The principle of analysis: When high energy electron beam penetrates the sample, scattering, absorption, interference and diffraction occur, which makes the contrast in the phase plane and display the image 
Spectrogram representation: Mass thickness contrast, bright field contrast image, dark field contrast image, lattice stripe image, and molecular image 
Information provided: Crystal Morphology, molecular weight distribution, micropore size distribution, polyphase structure, crystal lattice and defects, etc.


TEM working drawing

TEM imaging process

Stem imaging differs from TEM in that it is performed by scanning the sample with a focused electron beam. The difference from SEM is that the detector is placed under the sample and the detector receives a transmitted electron beam or an elastic scattered electron beam After magnification, the image of bright field and dark field are displayed on the screen.


STEM analysis image

The energy loss spectrum EELS is obtained by the elastic scattering on the surface of an incident electron beam processing sample, where the energy lost by some electrons is the characteristic value of an element in the sample The element composition, chemical bond and electronic structure of the thin sample can be analyzed by using EELS.


EELS schematics

10. Scanning Electron Microscopy SEM

Principle of analysis: Electron Technology is used to detect secondary electrons, backscattered electrons, absorbed electrons, x-rays and so on when high-energy electron beam interacts with the sample 
Spectrogram representation: Backscattering image, secondary electron image, absorption current image, line and surface distribution of elements, etc. 
Information provided: Fracture Morphology, surface microstructure, internal microstructure of the film, microelement analysis and Quantitative Element Analysis


SEM working image

The energy lost when the incident electron inelastic scattering with the Valence Electron of the atom in the sample is 30 to 50 ev, which excites the extranuclear electrons from the atom The Valence electrons whose energy is greater than the work of the material escape from the surface of the sample into the free electrons in the vacuum, that is, the secondary electrons.


Electron emission diagram


Secondary Electron Detection Map

The surface state of the secondary electron sample is very sensitive, which can effectively display the micro-morphology of the sample surface, and the resolution can reach 5 ~ 10nm.


Secondary Electron scanning imaging

The incident electrons are reflected near the nucleus without energy loss, including both the elastic backscattered electrons formed by the interaction with the nucleus and the inelastic backscattered electrons formed by the interaction with the outer electrons of the sample nucleus.


Backscatter pattern

When the back reflection signal is used to analyze the topography, the resolution is much lower than the secondary electron. According to the light and dark degree of the backscattered electron image, the relative atomic number of the corresponding region can be distinguished, and the microstructure of metal and its alloy can be analyzed.


EBSD mapping process
 

11. Atomic Force Microscopy AFM

Principle of analysis: A micro-cantilever sensitive to weak force is fixed at one end and has a tiny tip at the other end. Due to the extremely weak force between the tip atoms and the atoms on the sample surface, by controlling this force constancy during scanning, the microcantilever with the tip of the needle will undulate in the direction perpendicular to the surface of the sample. Thus, the information of the surface morphology of the sample can be obtained. 
Spectrogram representation: The microcantilever corresponds to the change of the position of the scanning points 
Information provided: Information on the surface morphology of the sample

Principle of AFM: Interaction between tip and surface atom

The scanning mode of AFM includes contact mode and non-contact mode, the contact mode uses the repulsion force between atoms to produce the profile of sample surface, and the non-contact mode uses the attraction force between atoms to produce the profile of sample surface.


Contact mode

12. Scanning Tunneling Microscope STM

Principle of analysis: The tunnel current intensity has an exponential dependence on the distance between the tip and the sample. According to the change of the tunnel current, we can get the tiny fluctuation information of the sample surface The 3d surface topography of the sample can be obtained directly, which is the principle of STM. 
Spectrogram representation: The fluctuation of the tunneling current is caused by the change of the surface topography of the sample 
Information provided: The 3D surface topography of the sample can be output after software processing


Probe

The tunneling current is very sensitive to the distance between the tip and the surface of the sample. The tunneling current increases by an order of magnitude when the distance decreases by 0.1 nm.


Tunnel current

When the tip is scanned on the surface of the sample, even if the surface only fluctuates on an atomic scale, the tunneling current will be displayed Then, the information is processed into three-dimensional image and displayed on the screen by the computer's measuring software and data processing software.






 

13. Atomic Absorption Spectroscopy AAS

Principle of analysis: The sample to be tested is atomized by an atomizer, and the atom to be tested absorbs the light of the Hollow Cathode lamp of the element to be tested, so that the energy detected by the detector is reduced and the absorbance is obtained. The absorbance is proportional to the concentration of the element to be measured


Test sample atomization



Atomic absorption and identification


14. Inductively Coupled Plasma ICP

Principle of analysis: The atoms and ions in the excited state are completely decomposed by argon plasma at high temperature. Because the atoms and ions in the excited state are unstable, the outer electrons will transition from the excited state to the lower energy level So the lines that give off the signature. The detector is used to measure the intensity of a certain wavelength after the grating is divided equally. The intensity of the light is proportional to the concentration of the elements to be measured.


ICP facility construction

Atoms and ions that form excited states

Detector detection

15. XRD

Principle of analysis: X-ray is the light radiation produced by the transition of inner-layer Electron under the bombardment of high-speed moving electron, which mainly includes continuous x-ray and characteristic x-ray. Crystals can be used as x Ray gratings, and the coherent scattering of these large numbers of atoms or ions / Molecules will interfere with the intensity of the scattered x rays, either increasing or decreasing. As a result of a large number of atomic scattering wave superposition, mutual interference and produce the maximum intensity of the beam known as the x-ray diffraction.
 
The Bragg formula can be used if the diffraction conditions are satisfied: 2dsinθ=λ
X Rays of known wavelengths are used to measure the angle and thus calculate the interplanar spacing D, which is used for x ray structural analysis, and x rays of known d are used to measure the angle and thus calculate the wavelength of the characteristic x rays The elements contained in the sample can then be identified from the available data.

 The following is an analysis using XRD to determine the structure of an unknown crystal:






Determination of unknown crystal structure by XRD
 

16. Nanoparticle Tracking Characterization

Analysis principle: Using light scattering principle, the brightness and spot size of scattered light imaging of different particle size are different on CCD, so the particle size can be determined The information of particle size distribution and concentration can be obtained when the sample with proper concentration is dispersed in liquid.


Scattering light imaging of different particle size in CCD


Actual sample test results


Data comparison between different techniques
 

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