Advantages and disadvantages of xps photoelectron spectroscopy, XPS characteristics of x ray photoel

The objects of these three types of spectroscopy analysis are different, and the information obtained is different. It's hard to compare them together.

X-ray photoelectron spectroscopy: used to (qualitatively) analyze the valence state and chemical morphology of atoms in compounds. The instrument is simple, and the spectral interpretation is simple.

Ultraviolet photoelectron spectroscopy: Analyzes the energy and action of electrons in valence orbitals. A lot of information can be obtained about the stability, reactivity, etc. of the molecule.

However, due to the role of electron transitions and vibrational energy levels, it is closely related to molecular symmetry. Graph parsing is complex. The instrument requirements are high.

Auger electron spectroscopy: It belongs to the secondary electron spectroscopy. It is mostly used for solids, or condensed matter.

Substances are analyzed for elements and valence. The atlas is simple, and the instrument requirements are high. It is often used in combination with X-ray photoelectron spectroscopy, fluorescence spectroscopy, and complementarity.

As a modern analysis method, XPS has the following characteristics:

1) All elements except H and HE can be analyzed, with the same order of magnitude sensitivity for all elements.

2) The spectral lines of the same energy level of adjacent elements are far apart and interfere less with each other, and the qualitative identification of the elements is strong.

3) Ability to observe chemical shifts. Chemical shifts are related to atomic oxidation states, atomic charges, and functional groups. Chemical shift information is used as the basis for XPS for structural analysis and chemical bond studies.

4) It can be quantitatively analyzed. It can determine both the relative concentration of elements and the relative concentration of different oxidation states of the same element.

5) It is a highly sensitive ultra-trace surface analysis technique. The sample is analyzed at a depth of about 2 nm, the signal comes from several atomic layers on the surface, the sample volume can be as small as 10-8g, and the absolute sensitivity can reach 10-18g.

An X-ray source is an X-ray tube with Al or Mg as the anode. Their photon energies are 1486 EV and 1254 EV, respectively. Install filters.

or monochromator) is to reduce photon energy dispersion. On the one hand, the function of the ion gun is to sputter to remove contamination from the surface of the sample, so as to obtain a clean surface, thereby improving the accuracy of its analysis. On the other hand, the sample can be sputtered and stripped to analyze the composition of the sample at different depths.

The sample holder in the sample chamber is equipped with a transmission mechanism, which can not only move in the perpendicular direction of X, Y and Z. It can also be rotated at a certain angle along a certain coordinate axis. This makes it easier to observe and analyze different parts of the sample.

The electron energy analyzer is a key component of the X-ray photoelectron spectrometer. Its role is to measure the distribution of electron energy and the relative strength of electrons of different energies. The electron energy analyzer and electron multiplier system are fully controlled by a microelectronic computer.