Overview of Atomic Fluorescence Spectroscopy Technology

1.

Atomic fluorescence was proposed as an instrumental analysis method in the mid-1960s, and it was actually applied after 1964

Atomic fluorescence spectroscopy is a method of spectral analysis

2.

The ground state atoms absorb a certain wavelength of radiation and are excited to a high energy state, and then the excited state atoms emit fluorescence with a characteristic wavelength in the form of optical radiation during the de-excitation process, and the analysis is performed according to the intensity of the characteristic fluorescence produced

3.

Atomic fluorescence is a process in which excited atoms emit energy in the form of light radiation.

(1) Resonance fluorescence: Atoms in the ground state or low-energy state absorb resonant radiation in the light source and transition to a high-energy state.

(2) Straight-jump line fluorescence: the valence electrons in the ground state are excited to transition to the high energy state (E ₂ ), and the excited state electrons in the high energy state then transition to the low energy state (E ₁ ) (but not the ground state).

(3) Step-line fluorescence: After the valence electron transitions from the ground state to the high energy state (E ₂ ), it drops to a lower energy state (E ₁ ) due to part of the energy lost by the excited collision

(4) Thermally assisted step-line fluorescence: the ground state atoms transition to a high energy state (E ₂ ) by absorbing light radiation , and the valence electrons in the high energy state are further excited under the action of thermal energy, and the electrons transition to a level close to the energy level E ₂ .

(5) Sensitized fluorescence: When the excited first atom collides with the second atom inelastically, energy may be transferred to the second atom, so that the second atom is excited, and the excited first atom The fluorescence produced during the de-excitation of two kinds of atoms is called sensitized fluorescence

4.

Including: an excitation light source, atomizer, spectroscopic systems, detection systems and data processing systems

Atomizer is divided into flame atomizer and flameless atomizer

Spectroscopic system: Atomic fluorescence spectrometers are divided into two types: dispersion type and non-dispersion type, and the non-dispersion type is more commonly used

5.
Features of atomic fluorescence spectroscopy technology

(1) The detection limit is low
.
The radiation intensity of atomic fluorescence is proportional to the excitation light source, and it is non-dispersive and has little light energy loss
.

(2) Good selectivity
.
Atomic spectroscopy is an inherent feature of elements and has good selectivity
.

(3) Good precision
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The measurement accuracy can reach about 1%
.

(4) Less interference
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The atomic fluorescence spectrum is relatively simple, and there is generally no spectral overlap interference.
The vapor generation separates the element to be measured from the matrix, which can eliminate the matrix interference
.

(5) The structure of the instrument is simple
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The non-dispersive instrument does not need a spectroscopic system, and the price is cheap, which is convenient for popularization and application
.

(6) The linear range of the analysis curve is wide
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Up to 3 to 5 orders of magnitude
.

(7) Simultaneous determination of multiple elements can be realized
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Atomic fluorescence is emitted in all directions in space, making it easier to make multiple instruments
.

(8) The amount of sample solution is small
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The injection volume is generally 1～5mL
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(9) The analysis speed is fast
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Generally, the measurement of a sample is completed in 10-15s
.

(10) Disadvantages: The number of elements that can be measured is small
.

6.
Factors affecting the analysis of atomic fluorescence spectroscopy

Fluorescence quenching effect: In atomic fluorescence spectroscopy, when high-temperature atomic vapor is excited to produce secondary fluorescence, the energy of excited atoms will also be released in other forms, such as inelastic collisions with atoms or molecules in the surrounding environment Loss of energy, in addition, it can also collide with the atomizer to cause non-radiation deactivation, which reduces the efficiency of atomic fluorescence
.
The physical and chemical changes that occur in the atomizer are very complex and vary with the analysis conditions and sample composition
.

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