CN114778506A - Integrated all-angle excitation source for atomic fluorescence spectrometer - Google Patents

Abstract

The invention relates to an integrated all-angle excitation source for an atomic fluorescence spectrometer, which belongs to the technical field of analytical instruments and consists of an excitation light source module and an annular atomizer module; the excitation light source module comprises an outer conductor (1), a microwave input port (2), a microwave antenna (3), an inner conductor (4) and the like, and the annular atomizer module comprises a flow guide ring (12), a working gas inlet (13), a sample inlet (14) to be detected and the like. The invention can be applied to atomic fluorescence spectrometers, and the excitation light source has the advantages of high radiation intensity, narrow spectral line, good spectral selectivity, capability of exciting the tested sample in a full angle in a 360-degree direction, and the like.

Description

Integrated all-angle excitation source for atomic fluorescence spectrometer

Technical Field

The invention belongs to the technical field of analytical instruments, and particularly relates to an integrated all-angle excitation source for an atomic fluorescence spectrometer.

Background

In the atomic spectrum analyzer, the excitation source (atomizer and/or excitation light source) is the key and core, and directly determines the structure and the analysis performance of the analyzer. In the existing atomic fluorescence spectrometer, the excitation light source is physically separated from the atomizer. Generally, an atomizer uses an oxyhydrogen flame in a quartz tube furnace, and an excitation light source uses a high-intensity hollow cathode lamp. The quartz tube atomizer is only suitable for elements capable of generating gaseous hydride at normal temperature, and hydrogen additionally generated by a hydride generation method and oxygen in air are combusted in an argon environment to realize sample atomization. Therefore, the types of the sample elements to be measured are limited.

The biggest problem of the hollow cathode lamp as the excitation light source is that the luminous intensity of the lamp is seriously drifted, the instrument needs to correct the standard curve at regular time, and the use is inconvenient for users. Secondly, the common hollow cathode lamp belongs to an acute line light source, and one hollow cathode lamp can only emit light radiation of an element corresponding to the hollow cathode lamp and can only be used for measuring a sample to be measured with the same type as the element. When different kinds of elements need to be measured, the hollow cathode lamp of different elements needs to be replaced. For example, if the elemental zinc in a sample is measured, a zinc element lamp is required to be configured for analysis. Due to the limitation of the types of the hollow cathode lamps, the types of the elements to be detected cannot be expanded randomly. In addition, for sample analysis of multiple elements, it is necessary to arrange lamps of multiple elements, and a larger instrument space is required.

In terms of instrument layout, in order to avoid the influence of the light radiation emitted by the excitation light source on the measurement of the weak atomic fluorescence signal, the direction of the light signal received by the fluorescence detector and the direction of the excitation light irradiating the atomizer are distributed at right angles or at an acute angle, and the excitation light beam irradiates the atomizer 180-degree range at best, as shown in fig. 1. It is well known that the intensity of the fluorescence signal is proportional to the intensity of the excitation light. Since the entire circumference of the quartz tube atomizer can receive excitation light only over a range of up to 180 degrees, the measurement sensitivity of the instrument is inevitably affected.

Disclosure of Invention

In order to overcome the defects of an excitation light source, an atomizer and instrument layout in the existing atomic fluorescence spectrometer, the invention provides an integrated all-angle excitation source, which is based on a microwave coaxial resonant cavity, wherein easily ionized working medium gas, combustible gas and combustion-supporting gas are introduced into the microwave coaxial resonant cavity, a microwave coupling plasma and high-temperature flame fusion excitation light source is obtained in the same space-time range, and the excitation of a standard sample injected in a pulse mode is completed to obtain pulse excitation light. Meanwhile, an annular atomizer is arranged inside or outside an outer conductor of the microwave coaxial resonant cavity, and atomization of a sample to be detected is completed by utilizing flame. The pulsed excitation light irradiates the sample to be detected after atomization in the direction of 360 degrees, and annular pulsed fluorescence is obtained.

The technical scheme of the invention is as follows:

an integrated full-angle excitation source for an atomic fluorescence spectrometer comprises an excitation light source module and an annular atomizer module; the microwave coaxial resonant cavity excitation system is characterized in that the excitation light source module is a microwave coaxial resonant cavity and comprises an outer conductor 1, a microwave input port 2, a microwave antenna 3, an inner conductor 4, an outer layer gas inlet 5, a middle pipe 6, a middle layer gas inlet 7, an inner pipe 8, an inner layer gas inlet 9, a standard sample pipe 10 and a standard sample inlet 11; the outer conductor 1, the inner conductor 4, the middle tube 6, the inner tube 8 and the standard sample tube 10 are sequentially nested and coaxial from outside to inside, the inner conductor 4, the middle tube 6, the inner tube 8 and the sample tube 10 are flush at the outlet end face, the inner conductor 4, the middle tube 6, the inner tube 8, the standard sample tube 10 and the outer conductor 1 form a microwave resonant cavity of a nested coaxial structure, and the characteristic impedance range of the resonant cavity is 50-80 ohms; the outer conductor 1 is a cylinder with a hollow inner part, and the inner diameter is 35-60 mm; the outlet end face of the nested coaxial structure formed by the inner conductor 4, the middle pipe 6 and the inner pipe 8 also has the function of a high-temperature flame combustion nozzle, and microwave coupling plasma and high-temperature flame are simultaneously generated at the outlet end face; the distance between the axis of the microwave input port 2 and the bottom surface of the microwave coaxial resonant cavity is 1/4 times of the wavelength of the used microwave, and the microwave antenna 3 introduces the microwave energy through the microwave input port 2 and is electrically connected with the inner conductor 4; the distance between the upper end face of the outer conductor 1 and the bottom face of the microwave coaxial resonant cavity is (2n +1)/4 times of the wavelength of the used microwave, wherein n is 1, 2 or 3;

the outer layer gas inlet 5 is positioned at the radial position of the lower part of the inner conductor 4 close to the bottom end of the inner conductor 4, the middle layer gas inlet 7 is positioned at the radial position of the lower part of the middle pipe 6 close to the bottom end of the middle pipe 6, and the inner layer gas inlet 9 is positioned at the radial position of the lower part of the inner pipe 8 close to the bottom end of the inner pipe 8, and radial gas inlet modes are adopted; the easily ionized gas entering from the outer layer gas inlet 5, the middle layer gas inlet 7 and the inner layer gas inlet 9 flows out in a laminar flow state at the outlet end face of the easily ionized gas, and is ionized by utilizing microwave electric field energy to form microwave coupling plasma; combustible gas and combustion-supporting gas entering from the outer layer gas inlet 5, the middle layer gas inlet 7 and the inner layer gas inlet 9 flow out in a layered state at a combustion nozzle formed by the outlet end faces of the combustible gas and the combustion-supporting gas, and are combusted to form high-temperature flame; the microwave coupling plasma and the high-temperature flame are fused in the same time and space to form a standard sample excitation light source; the standard sample inlet 11 is positioned at the bottom of the sample tube 10, high-concentration standard sample aerosol with the same element type as the sample to be detected enters the standard sample tube 10 through the standard sample inlet 11, an excitation light source enters the end face of the side of the outlet of the standard sample tube 10, and excitation light required by fluorescence measurement of the sample to be detected is obtained after excitation;

the annular atomizer module comprises a flow guide ring 12, a working gas inlet 13, a sample inlet 14 to be detected, a shielding gas inlet 15, an inner layer flow guide pipe 16, a middle layer flow guide pipe 17 and an outer layer flow guide pipe 18, and is positioned above the microwave input port 2 and on the inner side or the outer side of the outer conductor 1 of the microwave coaxial resonant cavity.

Specifically, when the annular atomizer is arranged on the inner side of the outer conductor 1 of the microwave coaxial resonant cavity above the microwave input port 2, the flow guide ring 12 is positioned in an annular space formed by the outer conductor 1 and the inner conductor 4, and the flow guide ring 12 is made of a non-metal material; the side surface of the outer conductor 1 is provided with a working gas inlet 13, a sample inlet 14 to be detected and a shielding gas inlet 15; a concave air guide groove is formed in the outer side of the guide ring 12, and a working air inlet 13 and a sample inlet 14 to be tested are designed in the inner side of the guide ring 12; the height of the air guide groove is respectively consistent with the height of a working air inlet 13 and the height of a sample inlet 14 to be detected on the side surface of the outer conductor 1; an inner layer draft tube 16, a middle layer draft tube 17 and an outer layer draft tube 18 are sequentially arranged on the inner side of the guide ring 12, and the inner layer draft tube 16, the middle layer draft tube 17 and the outer layer draft tube 18 are flush with each other at the upper outlet end face; the inner layer draft tube 16, the middle layer draft tube 17 and the outer layer draft tube 18 are made of non-metallic materials which do not influence the electromagnetic field distribution in the cavity, preferably quartz or ceramic; the inner layer flow guide pipe 16 and the middle layer flow guide pipe 17 form an annular atomizer of the sample to be detected, the atomization of the sample to be detected is completed, and the sample to be detected is excited in a full-angle mode by the pulse type excitation light source to generate annular fluorescence; working gas is introduced into an annular gap formed by the inner guide pipe 16 and the middle guide pipe 17; the working gas is introduced in the tangential direction or the radial direction of an annular gap formed by the inner layer draft tube 16 and the middle draft tube 17, flows to the end surface in a vortex or laminar flow mode and participates in the flame combustion process; the aerosol of the sample to be measured is introduced into an annular gap formed by the middle draft tube 17 and the outer draft tube 18; the shielding gas is introduced into an annular gap formed by the outer guide pipe 18 and the outer conductor 1; the shielding gas is introduced in a tangential or radial direction of the inner diameter of the outer conductor 1 to form a vortex or laminar shielding layer.

Specifically, when the annular atomizer is arranged on the outer side of the microwave coaxial resonant cavity outer conductor 1 above the microwave input port 2, the flow guide ring 12 is located outside the outer conductor 1 above the microwave input port 2, and the flow guide ring 12 is made of a metal or non-metal material; the side surface of the guide ring 12 is provided with a working gas inlet 13, a sample inlet 14 to be detected and a shielding gas inlet 15; an inner layer draft tube 16, a middle layer draft tube 17 and an outer layer draft tube 18 are sequentially arranged on the inner side of the flow guide ring 12, and the inner layer draft tube 16, the middle layer draft tube 17 and the outer layer draft tube 18 are flush with each other at the upper outlet end face; the inner layer draft tube 16, the middle layer draft tube 17 and the outer layer draft tube 18 can be made of non-metal materials, preferably quartz or ceramic; it may also be a metallic material, preferably brass; the outer conductor 1 and the inner layer flow guide pipe 16 form an annular atomizer of a sample to be detected, the atomization of the sample to be detected is completed, and the sample to be detected is excited by a pulse excitation light source at a full angle to generate annular fluorescence; the working gas is introduced into an annular gap formed by the outer conductor 1 and the inner guide pipe 16; the working gas is introduced in the tangential or radial direction of the annular gap formed by the outer conductor 1 and the inner guide pipe 16, flows to the end face in a vortex or laminar flow mode, and participates in the flame combustion process; the aerosol of the sample to be measured is introduced into an annular gap formed by the inner draft tube 16 and the middle draft tube 17; the shielding gas is introduced into an annular gap formed by the middle draft tube 17 and the outer draft tube 18; the shielding gas is introduced in the tangential direction or radial direction of the annular gap formed by the middle draft tube 17 and the outer draft tube 18, and forms a vortex or laminar shielding layer.

Preferably, the standard sample excitation light source is located on the central axis of the microwave coaxial resonant cavity (as shown in fig. 2), and the upper end surface of the inner conductor 4 of the microwave coaxial resonant cavity is 5-15 mm lower than the upper end surface of the annular atomizer; the atomizer partially surrounds the standard sample excitation light source at the same height; exciting light emitted by the standard sample excitation light source irradiates the atomizer surrounding the standard sample excitation light source in the 360-degree (full-angle) direction, and a sample to be detected is atomized in the atomizer and then excited by the exciting light in the full-angle direction to generate annular fluorescence; multiple fluorescence detectors can be arranged outside the fluorescence ring to improve the measurement sensitivity.

Has the beneficial effects that:

1. the light source function of the excitation source can replace the hollow cathode lamp used by the existing atomic fluorescence spectrometer, has high stability in time and space, and can obtain good measurement precision. Meanwhile, the excitation light source has high radiation intensity and narrow spectral line, and is favorable for subsequent fluorescence spectrum measurement. Moreover, the excitation light source has good spectral selectivity, the excitation spectral line is convenient to replace, only high-concentration standard solution which is introduced into the excitation light source and has the same type with the element to be detected needs to be replaced, and the excitation light source can be theoretically suitable for any element.

2. The atomizer function of the excitation source can replace oxyhydrogen flame used by the existing atomic fluorescence spectrometer, and ideal atomization efficiency and fluorescence efficiency can be obtained by adjusting gas flow, so that the measurement sensitivity is improved, and the detection limit is reduced. Meanwhile, the types of the measuring objects can be expanded, so that the measuring objects are not limited to elements fed by a hydride generation method.

3. The excitation source has a compact structure, the light source is positioned in the center, the tested sample can be excited at all angles in the 360-degree direction to generate annular fluorescence, the fluorescence signal can be received at all angles, and the measurement sensitivity is high.

Drawings

FIG. 1 is a prior art optical path diagram of an atomic fluorescence spectrometer.

FIG. 2 is a light path diagram of an atomic fluorescence spectrometer using an integrated all-angle excitation source of the present invention.

Fig. 3 is a schematic structural diagram of the integrated all-angle excitation source in embodiment 1.

Fig. 4 is a schematic structural diagram of the integrated all-angle excitation source in embodiment 2.

Detailed Description

Example 1

Fig. 3 is a schematic structural diagram of an integrated all-angle excitation source of the present invention, which is composed of an excitation light source module and a ring-shaped atomizer module. The excitation light source module is a microwave coaxial resonant cavity and comprises an outer conductor 1, a microwave input port 2, a microwave antenna 3, an inner conductor 4, an outer layer gas inlet 5, a middle pipe 6, a middle layer gas inlet 7, an inner pipe 8, an inner layer gas inlet 9, a standard sample pipe 10 and a standard sample inlet 11; the outer conductor 1, the inner conductor 4, the middle pipe 6, the inner pipe 8 and the standard sample tube 10 are sequentially nested and coaxial from outside to inside, the inner conductor 4, the middle pipe 6, the inner pipe 8 and the sample tube 10 are flush at the outlet end face, the inner conductor 4, the middle pipe 6, the inner pipe 8, the standard sample tube 10 and the outer conductor 1 form a microwave resonant cavity of a nested coaxial structure, and the characteristic impedance range of the resonant cavity is 50-80 ohms; the outer conductor 1 is a cylinder with a hollow inner part, and the inner diameter is 35-60 mm; the outlet end face of the nested coaxial structure formed by the inner conductor 4, the middle pipe 6 and the inner pipe 8 has the function of a high-temperature flame combustion nozzle, and can simultaneously obtain microwave coupling plasma and high-temperature flame.

The axis of the microwave input port 2 is 1/4 times of the used microwave wavelength away from the bottom surface of the microwave coaxial resonant cavity, and the microwave antenna 3 introduces microwave energy through the microwave input port 2 and is electrically connected with the inner conductor 4.

Preferably, the depth of the upper end surface of the outer conductor 1 and the bottom surface of the resonant cavity is (2n +1)/4 times of the wavelength of the microwave used, where n is 1, 2 or 3, and for example, when n is 1, the upper end surface of the outer conductor is about 90 to 100mm from the bottom surface of the resonant cavity. Preferably, the inner conductor 5 has an outer diameter of 10 to 18mm and an inner diameter of 9 to 16 mm.

Outer layer gas inlet 5 is located the radial position that 4 lower parts of inner conductor are close to 4 bottoms of inner conductor, and middle level gas inlet 7 is located the radial position that 6 lower parts of well pipe are close to 6 bottoms of well pipe, and inner layer gas inlet 9 is located the radial position that 8 lower parts of inner tube are close to 8 bottoms of inner tube, all adopts the radial mode of admitting air.

The easily ionized gas entering from the outer layer gas inlet 5, the middle layer gas inlet 7 and the inner layer gas inlet 9 flows out in a laminar flow state on the outlet end face of the easily ionized gas, and is ionized by utilizing microwave electric field energy to form microwave coupling plasma; combustible gas and combustion-supporting gas entering from the outer layer gas inlet 5, the middle layer gas inlet 7 and the inner layer gas inlet 9 flow out in a layered state at a combustion nozzle formed by the outlet end faces of the combustible gas and the combustion-supporting gas, and are combusted to form high-temperature flame; the microwave coupling plasma and the high-temperature flame are fused in the same time and space to form a standard sample excitation light source.

The standard sample inlet 11 is located at the bottom of the sample tube 10, and the high-concentration standard sample aerosol with the same element type as the sample to be measured enters the standard sample tube 10 through the standard sample inlet 11, and enters the excitation light source at the end face of the standard sample tube 10 at the outlet side, and after excitation, the excitation light required by the fluorescence measurement of the sample to be measured is obtained. After the standard sample enters the excitation light source in a pulse mode, the pulse type excitation light required by the fluorescence excitation of the sample to be detected can be obtained.

The annular atomizer module comprises a flow guide ring 12, a working gas inlet 13, a sample inlet 14 to be detected, a shielding gas inlet 15, an inner layer flow guide pipe 16, a middle layer flow guide pipe 17 and an outer layer flow guide pipe 18.

In this embodiment, the annular atomizer is disposed inside the outer conductor 1 of the microwave coaxial resonant cavity above the microwave input port 2, the flow guide ring 12 is located inside an annular space formed by the outer conductor 1 and the inner conductor 4, and the flow guide ring 12 is made of a non-metallic material; a working gas inlet 13, a sample inlet 14 to be tested and a shielding gas inlet 15 are designed on the side surface of the outer conductor 1; a concave air guide groove is designed on the outer side of the guide ring 12, and a working air inlet 13 and a sample inlet 14 to be detected are designed on the inner side of the guide ring 12; the height of the air guide groove is respectively consistent with the height of a working air inlet 13 and a to-be-detected sample inlet 14 which are designed on the side surface of the outer conductor 1; an inner layer draft tube 16, a middle layer draft tube 17 and an outer layer draft tube 18 are sequentially arranged on the inner side of the flow guide ring 12, and the inner layer draft tube 16, the middle layer draft tube 17 and the outer layer draft tube 18 are flush with each other at the upper outlet end face; the inner layer draft tube 16, the middle layer draft tube 17 and the outer layer draft tube 18 are made of quartz or ceramic, and electromagnetic field distribution in the cavity is not influenced. The inner layer flow guide pipe 16 and the middle layer flow guide pipe 17 form an annular atomizer of the sample to be detected, the atomization of the sample to be detected is completed, and the sample to be detected is excited in a full-angle mode by the pulse type excitation light source to generate annular fluorescence.

Working gas is introduced into an annular gap formed by the inner guide pipe 16 and the middle guide pipe 17; the working gas is introduced in the tangential direction of the annular gap formed by the inner layer draft tube 16 and the middle draft tube 17, flows to the end face in a vortex mode and participates in the flame combustion process. The working gas can also be introduced in the radial direction of an annular gap formed by the inner layer draft tube 16 and the middle draft tube 17, flows to the end face in a laminar flow mode and participates in the flame combustion process; the working gas can be mixed with combustion-supporting gas and combustible gas, and can also be mixed with inert gas; the combustion-supporting gas can adopt air or oxygen, and preferably adopts oxygen; the combustible gas can be hydrogen or methane, and hydrogen is preferably used.

The aerosol of the sample to be measured is introduced into an annular gap formed by the middle draft tube 17 and the outer draft tube 18; the sample aerosol to be tested is introduced into an annular gap formed by the middle guide pipe 17 and the outer guide pipe 18, and the sample aerosol to be tested can be mixed with combustible gas or combustion-supporting gas. The mixed combustion-supporting gas or combustible gas simultaneously participates in the flame combustion process. The aerosol of the sample to be detected can be mixed with inert gas, preferably, the inert gas is argon. And atomizing the sample to be detected in the flame on the end face of the annular atomizer.

The shielding gas is introduced into an annular gap formed by the outer guide pipe 18 and the outer conductor 1; the shield gas is introduced in the tangential direction of the outer conductor 1 and forms a vortex shield. The shielding gas may also be introduced in the radial direction of the outer conductor 1 and form a laminar flow shielding. The shielding gas can inhibit the diffusion of a sample to be detected to a free space, avoid the background interference caused by the atmosphere component involved in a flame atomization region, effectively prevent the quenching of atomic fluorescence and improve the intensity of the atomic fluorescence. The shielding gas may be oxygen or argon, preferably argon.

Example 2

Fig. 4 is another structural schematic diagram of the integrated all-angle excitation source of the invention, which is composed of an excitation light source module and a ring-shaped atomizer module. The excitation light source module is a microwave coaxial resonant cavity, and is the same as the excitation source in embodiment 1, and is not described herein again.

In the embodiment, the annular atomizer is arranged outside the microwave coaxial resonant cavity outer conductor 1 above the microwave input port 2, and the flow guide ring 12 is arranged outside the microwave coaxial resonant cavity outer conductor 1 above the microwave input port 2; a working gas inlet 13, a sample inlet 14 to be detected and a shielding gas inlet 15 are designed on the side surface of the guide ring 12; an inner layer draft tube 16, a middle layer draft tube 17 and an outer layer draft tube 18 are sequentially arranged on the inner side of the guide ring 12, and the inner layer draft tube 16, the middle layer draft tube 17 and the outer layer draft tube 18 are flush with each other at the position of the upper outlet end face.

The inner layer draft tube 16, the middle layer draft tube 17 and the outer layer draft tube 18 can be made of non-metal materials such as quartz or ceramic, and can also be made of metal materials such as brass.

The working gas is introduced into an annular gap formed by the outer conductor 1 and the inner guide pipe 16; the working gas is introduced in the tangential direction of the annular gap formed by the outer conductor 1 and the inner guide pipe 16, flows to the end surface in a vortex mode and participates in the flame combustion process. The working gas can also be introduced in the radial direction of an annular gap formed by the outer conductor 1 and the inner guide pipe 16, flows to the end face in a laminar flow mode and participates in the flame combustion process. The working gas can be mixed with combustion-supporting gas and combustible gas, and can also be mixed with inert gas; the combustion-supporting gas can adopt air or oxygen, and preferably adopts oxygen; the combustible gas can be hydrogen or methane, and hydrogen is preferably used.

The aerosol of the sample to be measured is introduced into an annular gap formed by the inner draft tube 16 and the middle draft tube 17; the sample aerosol to be tested is introduced into an annular gap formed by the inner draft tube 16 and the middle draft tube 17, and the sample aerosol to be tested can be mixed with combustible gas or combustion-supporting gas. The mixed combustion-supporting gas or combustible gas simultaneously participates in the flame combustion process. The aerosol of the sample to be detected can be mixed with inert gas, preferably, the inert gas is argon. And atomizing the sample to be detected in the flame on the end face of the annular atomizer.

The shielding gas is introduced into an annular gap formed by the middle draft tube 17 and the outer draft tube 18; the shielding gas is introduced in the tangential direction of the annular gap formed by the middle draft tube 17 and the outer draft tube 18 to form a vortex shielding layer. The shielding gas can also be introduced in the radial direction of the annular gap formed by the middle draft tube 17 and the outer draft tube 18 to form a laminar flow shielding layer. The shielding gas can inhibit the diffusion of a sample to be detected to a free space, avoid atmospheric components from being involved in a flame atomization area to generate background interference, effectively prevent quenching of atomic fluorescence and improve the intensity of the atomic fluorescence. The shielding gas can be oxygen or argon, and preferably, argon is used.

It can be understood that the excitation source of the invention has strong excitation capability because the excitation light source takes plasma as a main body, and has no drift problem of a hollow cathode lamp, so that the working curve of the instrument is not required to be corrected regularly, and the application is more convenient. Meanwhile, compared with the existing instrument, because the excitation light source excites the tested sample in the annular flame atomizer at all angles, a plurality of fluorescence detectors can be arranged around the atomizer and are close to each other, and higher measurement sensitivity can be obtained.

Claims (4)

1. An integrated all-angle excitation source for an atomic fluorescence spectrometer comprises an excitation light source module and an annular atomizer module; the microwave coaxial resonant cavity excitation device is characterized in that the excitation light source module is a microwave coaxial resonant cavity and comprises an outer conductor (1), a microwave input port (2), a microwave antenna (3), an inner conductor (4), an outer layer gas inlet (5), a middle pipe (6), a middle layer gas inlet (7), an inner pipe (8), an inner layer gas inlet (9), a standard sample pipe (10) and a standard sample inlet (11); the microwave resonant cavity comprises an outer conductor (1), an inner conductor (4), a middle pipe (6), an inner pipe (8) and a standard sample tube (10), wherein the outer conductor (1), the inner conductor (4), the middle pipe (6), the inner pipe (8) and the sample tube (10) are sequentially nested and coaxial from outside to inside, the inner conductor (4), the middle pipe (6), the inner pipe (8) and the sample tube (10) are flush at the outlet end face, the inner conductor (4), the middle pipe (6), the inner pipe (8), the standard sample tube (10) and the outer conductor (1) form a microwave resonant cavity of a nested coaxial structure, and the characteristic impedance range of the resonant cavity is 50-80 ohms; the outer conductor (1) is a cylinder with a hollow inner part, and the inner diameter is 35-60 mm; the outlet end face of the nested coaxial structure formed by the inner conductor (4), the middle pipe (6) and the inner pipe (8) also has the function of a high-temperature flame combustion nozzle, and microwave coupling plasma and high-temperature flame are simultaneously generated at the outlet end face; the distance between the axis of the microwave input port (2) and the bottom surface of the microwave coaxial resonant cavity is 1/4 times of the wavelength of the used microwave, and the microwave antenna (3) introduces microwave energy through the microwave input port (2) and is electrically connected with the inner conductor (4); the distance between the upper end surface of the outer conductor (1) and the bottom surface of the microwave coaxial resonant cavity is (2n +1)/4 times of the wavelength of the used microwave, wherein n is 1, 2 or 3;

the outer layer gas inlet (5) is positioned at the radial position of the lower part of the inner conductor (4) close to the bottom end of the inner conductor (4), the middle layer gas inlet (7) is positioned at the radial position of the lower part of the middle pipe (6) close to the bottom end of the middle pipe (6), the inner layer gas inlet (9) is positioned at the radial position of the lower part of the inner pipe (8) close to the bottom end of the inner pipe (8), and radial gas inlet modes are adopted; the easily ionized gas entering from the outer layer gas inlet (5), the middle layer gas inlet (7) and the inner layer gas inlet (9) flows out in a laminar flow state on the outlet end face of the easily ionized gas, and is ionized by utilizing microwave electric field energy to form microwave coupling plasma; combustible gas and combustion-supporting gas entering from the outer layer gas inlet (5), the middle layer gas inlet (7) and the inner layer gas inlet (9) flow out in a layered state through a combustion nozzle formed by the outlet end faces of the combustible gas and the combustion-supporting gas, and are combusted to form high-temperature flame; the microwave coupling plasma and the high-temperature flame are fused in the same time and space to form a standard sample excitation light source; the standard sample inlet (11) is positioned at the bottom of the sample tube (10), high-concentration standard sample aerosol with the same element type as the sample to be detected enters the standard sample tube (10) through the standard sample inlet (11), enters the excitation light source at the side end face of the outlet of the standard sample tube (10), and after excitation, excitation light required by fluorescence measurement of the sample to be detected is obtained;

the annular atomizer module comprises a flow guide ring (12), a working gas inlet (13), a sample inlet (14) to be tested, a shielding gas inlet (15), an inner layer flow guide pipe (16), a middle layer flow guide pipe (17) and an outer layer flow guide pipe (18), and the annular atomizer module is located above the microwave input port (2) and is located on the inner side or the outer side of the outer conductor (1) of the microwave coaxial resonant cavity.

2. The integrated all-angle excitation source for the atomic fluorescence spectrometer as claimed in claim 1, wherein when the annular atomizer is disposed inside the outer conductor (1) of the microwave coaxial resonant cavity above the microwave input port (2), the guide ring (12) is located inside an annular space formed by the outer conductor (1) and the inner conductor (4), and the guide ring (12) is made of a non-metallic material; the side surface of the outer conductor (1) is provided with a working gas inlet (13), a sample inlet (14) to be detected and a shielding gas inlet (15); a concave air guide groove is formed in the outer side of the guide ring (12), and a working air inlet (13) and a sample inlet (14) to be detected are designed in the inner side of the guide ring (12); the height of the air guide groove is respectively consistent with the height of a working air inlet (13) and the height of a sample inlet (14) to be detected on the side surface of the outer conductor (1); an inner layer draft tube (16), a middle layer draft tube (17) and an outer layer draft tube (18) are sequentially arranged on the inner side of the flow guide ring (12), and the inner layer draft tube (16), the middle layer draft tube (17) and the outer layer draft tube (18) are flush with each other at the upper outlet end face; the inner layer draft tube (16), the middle layer draft tube (17) and the outer layer draft tube (18) are made of non-metallic materials which do not influence the distribution of the electromagnetic field in the cavity; the inner layer flow guide pipe (16) and the middle layer flow guide pipe (17) form an annular atomizer of a sample to be detected, the atomization of the sample to be detected is completed, and the sample to be detected is excited by a pulse excitation light source at a full angle to generate annular fluorescence; working gas is introduced into an annular gap formed by the inner guide pipe (16) and the middle guide pipe (17); the working gas is introduced in the tangential direction or the radial direction of an annular gap formed by the inner layer draft tube (16) and the middle draft tube (17), flows to the end surface in a vortex or laminar flow mode and participates in the flame combustion process; the aerosol of the sample to be measured is introduced into an annular gap formed by the middle guide pipe (17) and the outer guide pipe (18); shielding gas is introduced into an annular gap formed by the outer guide pipe (18) and the outer conductor (1); the shielding gas is introduced in the tangential or radial direction of the inner diameter of the outer conductor (1) to form a vortex or laminar shielding layer.

3. The integrated all-angle excitation source for the atomic fluorescence spectrometer as claimed in claim 1, wherein when the annular atomizer is disposed outside the outer conductor (1) of the microwave coaxial resonant cavity above the microwave input port (2), the guide ring (12) is located outside the outer conductor (1) above the microwave input port (2), and the guide ring (12) is made of a metal or non-metal material; the side surface of the flow guide ring (12) is provided with a working gas inlet (13), a sample inlet (14) to be detected and a shielding gas inlet (15); an inner layer draft tube (16), a middle layer draft tube (17) and an outer layer draft tube (18) are sequentially arranged on the inner side of the flow guide ring (12), and the inner layer draft tube (16), the middle layer draft tube (17) and the outer layer draft tube (18) are flush with each other at the position of the upper outlet end face; the inner layer draft tube (16), the middle layer draft tube (17) and the outer layer draft tube (18) are made of non-metal materials or metal materials; the outer conductor (1) and the inner layer flow guide pipe (16) form an annular atomizer of a sample to be detected, atomization of the sample to be detected is completed, and the sample to be detected is excited in a full-angle mode by the pulse type excitation light source to generate annular fluorescence; the working gas is introduced into an annular gap formed by the outer conductor (1) and the inner guide pipe (16); the working gas is introduced in the tangential or radial direction of an annular gap formed by the outer conductor (1) and the inner guide pipe (16), flows to the end surface in a vortex or laminar flow mode, and participates in the flame combustion process; the aerosol of the sample to be tested is introduced into an annular gap formed by the inner draft tube (16) and the middle draft tube (17); shielding gas is introduced into an annular gap formed by the middle guide pipe (17) and the outer guide pipe (18); the shielding gas is introduced in the tangential direction or the radial direction of an annular gap formed by the middle draft tube (17) and the outer draft tube (18), and forms a vortex flow or laminar flow shielding layer.

4. The integrated all-angle excitation source for the atomic fluorescence spectrometer according to any one of claims 1 to 3, wherein the standard sample excitation light source is located on a central axis of the microwave coaxial resonant cavity, and an upper end surface of the inner conductor (4) of the microwave coaxial resonant cavity is 5-15 mm lower than an upper end surface of the annular atomizer; the atomizer partially surrounds the standard sample excitation light source at the same height; the excitation light emitted by the standard sample excitation light source irradiates the atomizer surrounding the standard sample excitation light source in the 360-degree direction, and the sample to be detected is atomized in the atomizer and then excited by the excitation light at a full angle to generate annular fluorescence.

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