SJ/Z 3206.2-1989 Excitation sources and performance requirements for emission spectral analysis SJ/Z3206.2-1989 standard download decompression password: www.bzxz.net
This standard applies to the excitation sources and performance requirements for spectral analysis, and is used to guide spectral analysis workers to select laser sources and determine their analysis methods.

Guiding Technical Documents of the Ministry of Electronics Industry of the People's Republic of China Excitation Sources and Performance Requirements for Emission Spectroscopy Analysis SJ/Z8206.2—89
This standard applies to the excitation sources and performance requirements for spectral analysis, and is used to guide spectral analysis workers to select excitation sources and determine their analysis methods.
1 Basic requirements for excitation
1.1 It has a low analytical detection limit. For most elements, when the content in the sample is very low, the excitation source can also be excited to emit sufficient light intensity to be discovered and measured. 1.2 The excitation stability and reproducibility are good. The various parameters of the excitation source and the excitation process should remain stable and can be repeated and reproduced.
1.3 The sensitivity (concentration sensitivity) is high, and the corresponding spectral line intensity changes caused by small changes in element concentration should be large. 1.4 The linear range of analysis is wide, the content of the analyzed element is linearly related to the spectral line intensity, and the dynamic range should be wide. 1.5 The background is small, and the intensity of the band spectrum and continuous spectrum generated by excitation is small. 1.6 The different physical structures and chemical compositions of the samples have little impact on the analysis results, and the matrix effect is small. 1.7 There must be sufficient luminous brightness to shorten the noise time of the analysis, speed up the analysis, or be able to record the emission spectrum of small samples.
2 Working principle and performance of the excitation source
2.1 DC arc generator
The sample electrode and ballast resistor are connected in series to the DC power supply. After ignition in a certain way, a DC arc discharge is generated between the electrodes. The DC power supply can be a DC generator and various rectifiers. The voltage is generally 220~400V and the current intensity is 2~30A. The basic circuit of the DC arc is shown in Figure 1. R
Figure 1 DC arc circuit
Approved by the Ministry of Electronics Industry of the People's Republic of China on February 1, 1989 and implemented on March 1, 1989
R Arc variable resistor (ballast resistor)
G—Analysis gap
SJ/Z3206.2—89
R1-——Ignition circuit resistor
L1--High-frequency coupling primary coil
—Ammeter C bypass electric passenger L-High-frequency coupling secondary coil T—Step-up transformerbZxz.net
C1-—-Ignition circuit capacitor
G1-Auxiliary discharge gap
The DC arc circuit is divided into two parts: low-voltage DC power supply circuit and high-frequency ignition circuit. The AC passes through the step-up transformer T (stepped up to 3000V), which makes the oscillation circuit composed of capacitor C1, inductor L, and auxiliary discharge gap G generate high-frequency discharge. By L, through L coupling (boosting) to the DC power supply circuit, the analysis gap G is broken down to generate a DC arc self-sustaining discharge.
The relationship between the arc (DC or AC) discharge current I, the supply voltage U, the ballast resistor R and the resistance r of the analysis gap is expressed by the following formula.
(1)
Where: I-arc discharge current, A, U-supply voltage, V, R-ballast resistor,,-analysis gap resistance, 2.
It can be seen from formula (1) that only when the ballast resistor is much larger than the resistance of the analysis gap, that is, when R>>r, can a stable arc discharge be obtained.
When using a DC arc, it is necessary to distinguish whether the sample is placed on the anode or the cathode to obtain different excitation effects. The discharge current intensity should be appropriately selected. 2.2 AC arc generator
AC arcs are divided into high-voltage AC arcs and low-voltage AC arcs. High-voltage AC arcs can be ignited by their own high voltage, but the device is complex and not safe to use, so they are rarely used. The circuit of the widely used low-voltage AC arc is similar to that of the DC power supply, except that the low-voltage DC power supply is converted into AC power supply. Its basic circuit is shown in Figure 2.
Figure 2 AC arc circuit
R——arc variable resistor (ballast resistor) SJ/Z3206.2-89
A-ammeter
C bypass capacitor
L---high-frequency secondary coil G--analysis gap R1--ignition loop resistor T-boosting transformer G-assisted discharge gap
L1-combined primary coil
C1--ignition loop capacitor
AC power drive discharge must use high-frequency sparks to ignite in reverse every half cycle to periodically ionize the analysis gap in order to continue the AC arc discharge. The more times the ignition is performed, the longer the arcing time is and the shorter the extinguishing time is. The number of ignitions is mainly determined by the discharge gap G1 and the resistor R1 in the high-frequency ignition circuit. The voltage waveforms on G1 and C1 can be observed with an oscilloscope. R is disconnected, a mirror is shaken, and the discharge of the gap G is observed and analyzed to distinguish the number of ignitions. In order to accurately control the number of ignitions and the ignition phase, an interrupter driven by a synchronous motor can be connected to the high-frequency ignition circuit or a pulse-triggered ignition circuit can be used. The stability of high-frequency ignition (number of ignitions and phase) can affect the stability of AC arc discharge. 2.8 Voltage-compressed spark generator
Voltage-compressed sparks work similarly to low-voltage AC arcs. By increasing the bypass capacitor to more than tens of μF, low-voltage spark discharges can be obtained. It uses a relatively low voltage to charge the capacitor, discharge it in a short time, and obtain an excitation source with a large current. Its basic circuit is shown in Figure 3. Figure 3 Low-voltage spark circuit
R: A-type variable resistor (ballast resistor) A-type current meter C-type capacitor L-type secondary coil G-type high-frequency oscillation circuit consists of high-voltage transformer T, inductor 1 capacitor C, and discharge circuit G. The high-frequency circuit includes the power supply R, the photoelectric circuit composed of capacitor C, and the inductor G. The high-frequency current in the circuit depends on the ratio of inductance L to current. The larger the ratio, the higher the voltage. The increase in the number of ignitions increases the number of discharge pulses per half cycle, and the discharge is "soft". The inductance of the discharge circuit decreases, making the discharge "hard".
The low-voltage spark discharge power supply has a strong pulse nature and a large current density. As long as the device flashes several times, sufficient 13
spectral line intensity can be obtained.
2.4 High-voltage spark generator
SJ/Z3206.2-89
The spark generator is supplied by AC power to the primary coil of the high-voltage transformer. The secondary coil generates a high voltage (greater than 8000V) to charge the capacitor. When it reaches a certain voltage value, it breaks down the analysis gap or the auxiliary gap, or both break down and discharge. When the voltage is not enough to maintain the discharge, it extinguishes. This process is repeated continuously to maintain the spark discharge. The energy W released by the capacitor each time it discharges is: w-1cv2
Where: C is the capacitance of the capacitor,
V is the charging voltage of the capacitor before discharge.
2.4.1 Simple spark generator
The simple spark generator circuit is shown in Figure 4. Figure 4 Simple spark circuit
R_—Resistor
A.-Ammeter
Tr--Step-up transformer
LVariable inductor
GAnalysis gap
C-Variable capacitor
When the resistance in the oscillation circuit composed of variable capacitor C, variable inductor L and discharge gap G is very small, the frequency f of the oscillation discharge is expressed by the following formula: f=1/(2VLC)
Wherein, f—oscillation discharge frequency, Hz, L—variable inductor, H, (3)
LVariable capacitor, μF.
Simple spark discharge is related to the state of the analysis gap, so the stability is poor, and the discharge energy is large. 2.4.2 Controlled spark generator
In order to improve the stability of simple spark discharge, a controlled spark circuit is used. There are three types of controlled sparks: static controlled gap, rotating controlled gap and electronic control. 2.4.2.1 Static controlled gap spark generator
The static controlled gap spark generator adds a controlled discharge gap (auxiliary gap) compared to the simple spark, and connects a large resistor or a large inductor coil in parallel with the analysis gap. Its basic circuit is shown in Figure 5. R resistor
A current meter
G1 controlled gap
L—large inductance
SJ/Z3206.2--89
Figure 5 Static control gap spark circuit
L-variable inductance
C variable capacitor
Step-up transformer
G--analysis gap R1 large resistance
When the variable capacitor C is charged, the analysis gap G is short-circuited by the resistor R, so the voltage at both ends of the control gap G gradually increases. When it reaches its breakdown voltage, the control gap discharges, the resistance drops sharply, and all the voltage falls on R, that is, the analysis gap G, which is broken down and discharged. The same effect can be achieved by connecting a large self-inductance line L in parallel with the analysis gap. This circuit uses high resistance (or impedance) to protect the analysis gap from the influence of unstable power supply voltage, and the discharge voltage depends on the control gap.
When using a spark source for analysis, it is necessary to select the size of voltage, capacitance, and inductance. 2.5 Inductively coupled high-frequency plasma
The main equipment of plasma is a high-frequency generator with an output power of several kW and a frequency of tens of MHz, and a water-cooled induction coil wound with a copper tube, which couples the radio frequency power into the plasma tube. The plasma tube is made of a coaxial quartz tube. As shown in Figure 6. The cooling gas argon passes through the space between the outer and middle quartz tubes, surrounds the plasma, maintains and stabilizes the plasma torch and cools the tube wall.
SJ/Z3206.2-89
Cold state gas
Plasma gas
Test gas
Figure 6 Inductively coupled high-frequency plasma torch
Plasma gas is introduced from the lower end through the middle tube to ignite the plasma and protect the inner tube. When passing through the coil, the plasma gas is ionized due to high-frequency induction heating, and a plasma torch is formed under the triggering of the external auxiliary ionization source. The atomized sample aerosol and carrier gas are introduced from the lower end of the inner tube and sprayed into the plasma torch from the upper end. The sample is excited in the central channel of the plasma torch.
The main factors affecting the intensity of the plasma spectrum are the anode current of the high-frequency oscillator tube, the pressure of the atomized gas, and the interception height of the plasma torch.
2.6 Lasers have been applied to optical spectrum analysis. Laser microscopic spectrum analysis uses the high brightness and good directionality of lasers to evaporate the sample in the component area, stimulate the absorption spectrum and perform analysis. 2.6.1 Laser spectrum analysis devices generally include laser generators, microscopic aiming parts, auxiliary discharge electrodes, power supplies and control systems.
2.6.1.1 Laser generators are divided into general, pulsed and giant pulse lasers. Generally, laser generators are mainly composed of three parts: working material, excitation energy and energy cavity, as shown in Figure 7. 1--Total reflection diaphragm
SJ/Z3206.2--89
Figure 7 Schematic diagram of pulse solid laser structure
2 Focusing cavity
Pulse xenon lamp
4 Working substance
a. The working substances mainly include neodymium glass, ruby, yttrium aluminum garnet, etc. b. The excitation energy is mostly a high-voltage pulse xenon lamp. 5--. Semi-reflective diaphragm
c The resonant cavity is composed of plane mirrors at both ends of the working substance. One of them is fully reflective and the other is semi-reflective. The laser is output from one end of the semi-reflective mirror. 2.6.1.2 Principle of laser generation Take neodymium glass as an example. Under normal circumstances, the neodymium ions in neodymium glass are in the ground state 1 (see Figure 8). Due to the excitation of the xenon lamp, the sensitive ions absorb light energy and are excited from energy level 1 to energy level 2. If the lifetime of energy level 2 is shorter than that of energy level 3, the particles quickly move to metastable state 3 and accumulate. Due to the vacancy of energy level 4, a population inversion is quickly formed between 3 and 4. When triggered by a photon that meets the requirements of formula (4), a stimulated radiation transition from energy level 3 to 4 can be generated. Through the action of the resonant cavity, the photons resonate to form a laser. hy=E,-Es
where hu--photon energy
E.~Energy of neodymium ion in metastable state
E. -Energy of neodymium ion in vacancy state.
Note: Particle inversion refers to the state in which the number of atoms in high energy level is greater than the number of atoms in low energy level under the excitation of external energy.
SJ/Z8206.2--89
The laser is focused on the analysis sample through the optical system to evaporate it. The sample vapor is excited when the auxiliary electrode discharges, and its spectrum is recorded for analysis.
The main parameters of the laser source are the output energy size and stability, as well as the minimum diameter of the laser beam. 3Purpose of excitation source
Each excitation source has its most suitable purpose. The following table lists their main application ranges. Main application scope of excitation source
Current arc
AC arc
Low voltage spark
High voltage spark
Plasma
4 Excitation index
Application scope
Qualitative and quantitative analysis of ores, minerals, pure substances, inorganic chemical products, etc. Quantitative, semi-quantitative and qualitative analysis of metals and alloys Determination of difficult-to-excite elements N, H, O, C, S, P Quantitative analysis of metals and alloys
Quantitative analysis of solutions and samples that can be turned into solutions Qualitative and semi-quantitative analysis of micro-areas
The excitation index is the ratio of the intensities of two spectral lines with a large difference in excitation energy in an element, which can be used as a rough estimate of the excitation performance level. It is a very complex function of the temperature and electron density of the excited state and the ionized state. The following are several pairs of lines for measuring the excitation index: FeI2813.29/FeⅡ2813.61
FeI2501.70/FeI2476.27
FeI3016.19/FeⅢ3013.12
NiI2419.31/NiII2448.35
Additional Notes:
This standard was proposed by the Electronic Standardization Institute of the Ministry of Machinery and Electronics Industry. The drafting of this standard was carried out by the Electronic Standardization Institute of the Ministry of Machinery and Electronics Industry. The main drafters of this standard were Wang Jinxue, Zhao Changchun and Huang Wenyu.2 Principle of laser generation Taking neodymium glass as an example, under normal circumstances, the neodymium ions in neodymium glass are in the ground state 1 (see Figure 8). Due to the excitation of the xenon lamp, the sensitive ions absorb light energy and are excited from energy level 1 to energy level 2. If the energy level 2 has a shorter lifetime than energy level 3, the particles will quickly move to the metastable state 3 and accumulate. Due to the vacancy of energy level 4, a population inversion is quickly formed between 3 and 4. When triggered by a photon that meets the requirements of formula (4), a stimulated radiation transition from energy level 3 to 4 can be generated. Through the action of the resonant cavity, the photons resonate to form a laser. hy=E,-Es
where hu--photon energy
E.~Energy of neodymium ion in metastable state
E. -Energy of neodymium ion in vacancy state.
Note: Particle inversion refers to the state in which the number of atoms in high energy level is greater than the number of atoms in low energy level under the excitation of external energy.
SJ/Z8206.2--89
The laser is focused on the analysis sample through the optical system to evaporate it. The sample vapor is excited when the auxiliary electrode discharges, and its spectrum is recorded for analysis.
The main parameters of the laser source are the output energy size and stability, as well as the minimum diameter of the laser beam. 3Purpose of excitation source
Each excitation source has its most suitable purpose. The following table lists their main application ranges. Main application scope of excitation source
Current arc
AC arc
Low voltage spark
High voltage spark
Plasma
4 Excitation index
Application scope
Qualitative and quantitative analysis of ores, minerals, pure substances, inorganic chemical products, etc. Quantitative, semi-quantitative and qualitative analysis of metals and alloys Determination of difficult-to-excite elements N, H, O, C, S, P Quantitative analysis of metals and alloys
Quantitative analysis of solutions and samples that can be turned into solutions Qualitative and semi-quantitative analysis of micro-areas
The excitation index is the ratio of the intensities of two spectral lines with a large difference in excitation energy in an element, which can be used as a rough estimate of the excitation performance level. It is a very complex function of the temperature and electron density of the excited state and the ionized state. The following are several pairs of lines for measuring the excitation index: FeI2813.29/FeⅡ2813.61
FeI2501.70/FeI2476.27
FeI3016.19/FeⅢ3013.12
NiI2419.31/NiII2448.35
Additional Notes:
This standard was proposed by the Electronic Standardization Institute of the Ministry of Machinery and Electronics Industry. The drafting of this standard was carried out by the Electronic Standardization Institute of the Ministry of Machinery and Electronics Industry. The main drafters of this standard were Wang Jinxue, Zhao Changchun and Huang Wenyu.2 Principle of laser generation Taking neodymium glass as an example, under normal circumstances, the neodymium ions in neodymium glass are in the ground state 1 (see Figure 8). Due to the excitation of the xenon lamp, the sensitive ions absorb light energy and are excited from energy level 1 to energy level 2. If the energy level 2 has a shorter lifetime than energy level 3, the particles will quickly move to the metastable state 3 and accumulate. Due to the vacancy of energy level 4, a population inversion is quickly formed between 3 and 4. When triggered by a photon that meets the requirements of formula (4), a stimulated radiation transition from energy level 3 to 4 can be generated. Through the action of the resonant cavity, the photons resonate to form a laser. hy=E,-Es
where hu--photon energy
E.~Energy of neodymium ion in metastable state
E. -Energy of neodymium ion in vacancy state.
Note: Particle inversion refers to the state in which the number of atoms in high energy level is greater than the number of atoms in low energy level under the excitation of external energy.
SJ/Z8206.2--89
The laser is focused on the analysis sample through the optical system to evaporate it. The sample vapor is excited when the auxiliary electrode discharges, and its spectrum is recorded for analysis.
The main parameters of the laser source are the output energy size and stability, as well as the minimum diameter of the laser beam. 3Purpose of excitation source
Each excitation source has its most suitable purpose. The following table lists their main application ranges. Main application scope of excitation source
Current arc
AC arc
Low voltage spark
High voltage spark
Plasma
4 Excitation index
Application scope
Qualitative and quantitative analysis of ores, minerals, pure substances, inorganic chemical products, etc. Quantitative, semi-quantitative and qualitative analysis of metals and alloys Determination of difficult-to-excite elements N, H, O, C, S, P Quantitative analysis of metals and alloys
Quantitative analysis of solutions and samples that can be turned into solutions Qualitative and semi-quantitative analysis of micro-areas
The excitation index is the ratio of the intensities of two spectral lines with a large difference in excitation energy in an element, which can be used as a rough estimate of the excitation performance level. It is a very complex function of the temperature and electron density of the excited state and the ionized state. The following are several pairs of lines for measuring the excitation index: FeI2813.29/FeⅡ2813.61
FeI2501.70/FeI2476.27
FeI3016.19/FeⅢ3013.12
NiI2419.31/NiII2448.35
Additional Notes:
This standard was proposed by the Electronic Standardization Institute of the Ministry of Machinery and Electronics Industry. The drafting of this standard was carried out by the Electronic Standardization Institute of the Ministry of Machinery and Electronics Industry. The main drafters of this standard were Wang Jinxue, Zhao Changchun and Huang Wenyu.
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