CN101311720A - Knudsen Cell-mass spectrometer for gas adsorbing /desorption kinetic determination - Google Patents
Knudsen Cell-mass spectrometer for gas adsorbing /desorption kinetic determination Download PDFInfo
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- CN101311720A CN101311720A CNA2007100994426A CN200710099442A CN101311720A CN 101311720 A CN101311720 A CN 101311720A CN A2007100994426 A CNA2007100994426 A CN A2007100994426A CN 200710099442 A CN200710099442 A CN 200710099442A CN 101311720 A CN101311720 A CN 101311720A
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Abstract
The invention belongs to the field of mass spectrometer technology and more particularly provides a Knudsen Cell-mass spectrometer which can be used in the measurement of absorption/desorption amount of transient gas absorption/desorption dynamics, comprising a gas leakage valve, a Knudsen Cell, a continuous adjustable iris or an changeable leakage hole, a transition chamber, a valve, a mass spectrometer, a temperature measurement system, a temperature control system, a pressure measurement system and a pressure control system; wherein, the gas leakage valve servers as an interface of normal pressure and low pressure and can control the volume of gas which enters a vacuum system; the Knudsen Cell is composed of a sample cover which can move vertically, a fixed sample pool, a temperature control system and a pressure measurement control system; the mass spectrometer serves as a gas detector; all internal cavity surfaces have chemical inertia after the surface treatment. The Knudsen Cell-mass spectrometer provided by the invention can accurately measure the absorption and desorption dynamics constants and absorption amount of gas on powder samples and is particularly suitable for relevant study on fields of physical chemistry and atmospheric environments.
Description
Technical field
The invention belongs to the mass spectrometer technical field.Be specifically related to Knudsen cell and mass spectrometer.
Background technology
Picked-up (absorption, absorption, catalytic reaction) and the desorption of gas on the pressed powder sample is the significant process in atmospheric environment chemistry and physical chemistry field.In the atmospheric environment field, trace gas is the research trace gas moves transformation rule on the environment micro-interface an indispensable kinetic parameter at the picked-up coefficient on the pressed powder sample.In the physical chemistry field, transient state absorption/desorption rate constant, the adsorbance/desorption rate of gas on solid powder art sample also is the important parameter of the microprocess of research gas-solid interface.
At present, the specific surface area measuring instrument based on Blang's Nore-Emmett-Taylor (BET) multilayer adsorption theory can be used for the mensuration of gas in the adsorbance of pressed powder sample surfaces.For example the specific surface area measuring instrument of production such as Quantachrome Instruments, Micromeritics company all can be used for gas physics, chemisorption quantitative determination on the pressed powder sample.Yet this method belongs to stable state assay method, length consuming time, and can not measure transient state rate of adsorption constant.Temperature programmed desorption (TPD) is usually used in the mensuration of desorbing gas process on the pressed powder sample.Wherein utilize mass spectrum can measure the transient state desorption process of gas, but can not obtain the information of adsorption process simultaneously for the TPD-MS of detecting device.And utilize Knudsen cell to be connected with mass spectrometer, powdered sample can expose or be isolated from tested gas atmosphere in the Knudsen cell, thereby can further measure its desorption rate constant and desorption rate finishing gas after rate of adsorption constant on the powdered sample and adsorbance mensuration; Utilize mass spectrometric high time resolution, can obtain the transient state dynamics data, thus for fast measuring gas on powdered sample, adsorb/desorption kinetic, adsorbance/desorption rate provide new thinking.
Summary of the invention
The present invention combines Knudsen cell and mass spectrometric advantage, the Knudsen cell-mass spectrometer that provides, can be in-60 ℃ of-250 ℃ of scopes transient state absorption/desorption kinetic, the adsorbance/desorption rate of fast measuring gas on the pressed powder sample.
Knudsen cell-mass spectrometer provided by the invention as shown in Figure 1, comprise gas leak valve (1), Knudsen cell (2), continuous adjustable iris (3), transition chamber (4), the family of power and influence (5), aperture, mass spectrum vacuum chamber (6), temperature control system (14), temperature measurement system (15), pressure-measuring system (8) and control pressurer system (9), wherein leak valve, Knudsen cell, continuous adjustable iris or replaceable leak, transition chamber, the family of power and influence, mass spectrometer connect successively.
Knudsen cell of the present invention comprises independently vacuum chamber, gas sampling interface, escape of gas hole interface, vacuum gauge interface, sample cell, sample lid, sample stage, circulating fluid temperature control and measurement system.All inside surface plating Teflon films of Knudsen cell carry out surperficial inerting to be handled, to eliminate the absorption of wall to gas composition.Bury in sample cell places on the sample stage of platinum-resistance thermometer, its measurement range is-100 ℃-250 ℃, and measuring error is ± 0.1 ℃.Seal with Teflon O type circle between sample stage and the sample lid.The sample lid links to each other with vertically moving stretching bar, thereby sample can be isolated or be exposed in the gas composition.Sample temperature of the present invention is controlled by the circulating fluid medium.Can be adjustable continuously from-60 ℃～0 ℃ and 0 ℃～250 ℃ segmentations, its error range is ± 0.1 ℃.
Transition chamber of the present invention is connected with difference pump (turbomolecular pump) and forepump.The mass spectrum vacuum chamber is connected with turbomolecular pump and forepump.Knudsen cell is connected with continuous adjustable iris or replaceable leak with transition chamber, thus the working pressure of control Knudsen cell.The pressure of transition chamber and mass spectrum vacuum chamber is measured respectively by vacuum gauge independently.Connect with the family of power and influence between transition chamber and the mass spectrum vacuum chamber.When the family of power and influence is used to change sample, guarantee that the vacuum tightness of mass spectrometer system is constant.The preposition aperture of mass spectrometer detector is used to limit the gas flow that enters mass detector.
Mass spectrometer of the present invention is used for the online detection of gas component concentrations.
Description of drawings
Fig. 1 is that Knudsen cell-mass spectrometric structure is always schemed.
Label among Fig. 1: 1 is leak valve, and 2 is Knudsen cell, and 3 is continuous adjustable iris, and 4 is transition chamber, and 5 is the family of power and influence, and 6 is the mass spectrum vacuum chamber, and 7 is mass spectrum RF head, and 8 is vacuum gauge, and 9 is turbomolecular pump.
Fig. 2 is the structural representation of Knudsen cell.
Label among Fig. 2: 10 for connecing the iris flange, and 11 are sample lid stretching bar, and 12 for connecing the vacuum gauge flange, and 13 for connecing the leak valve flange, and 14 are circulation heating (cooling) media lines, and 15 is thermopair, and 16 is the Knudsen cell cavity, 17 samples lid, 18 sample stage.
Fig. 3 is that cos (OCS) gas is at α-Fe
2O
3On curve of adsorption kinetics.
Embodiment
Below in conjunction with drawings and Examples the present invention is further described:
In the present embodiment, Knudsen cell as shown in Figure 2.It is material that the Knudsen cell cavity adopts accurately machined stainless steel cylinder, and external diameter is 60mm, and internal diameter is 56mm, height 60mm.Sample stage is external diameter 46mm, the stainless steel disk of height 10mm, and there is a diameter 30mm in its front, the notch of degree of depth 1.5mm and external diameter 40mm, internal diameter 33mm, the O type ring recess mouth of degree of depth 2.2mm.Bury-100 ℃～250 ℃ platinum-resistance thermometer in the sample stage.Sample stage places external diameter 46mm, and on height 23mm flexible, it constitutes a cavity with the Knudsen cell base is common, is used to circulate medium and sample is carried out temperature controls.Sample cell is internal diameter 26mm, the stainless steel shallow slot of degree of depth 1mm.The sample lid is diameter 46mm, the blind flange of thickness 3mm.But it is connected with the stretching bar of vertical movement.Seal with O type circle between stretching bar and the Knudsen cell lid.Connect flange and 1 CF63 flange of 2 CF16 on the Knudsen cell cavity respectively, be connected with leak valve, vacuum gauge, iris or replaceable leak respectively.All inside surfaces of Knudsen cell all plate the Teflon film.
In the present embodiment, with powdered sample put with sample cell in, close sample lid, regulate leak valve and iris and to Knudsen cell, arrive suitable pressure or gas molecule concentration.After mass signal reaches stable state, open the sample lid, obtain the kinetics of adsorption data of gas on powdered sample.Proofread and correct by the gas molecule flow, can obtain the adsorbance of gas on powdered sample.Adsorb saturated after, close sample lid, leak valve successively, open iris fully.To whole system vacustat, open the sample lid, obtain desorption kinetic data and desorption rate.
In the present embodiment, Fig. 3 is that cos (OCS) gas is at 141.3mg α-Fe
2O
3On curve of adsorption kinetics.According to the Knudsen cell fundamental equation, can calculate transient state absorption/desorption mathematic(al) constant.And can measure saturated extent of adsorption according to the gaseous molecular quantity consumed.
Claims (9)
1, Knudsen cell-mass spectrometer comprises gas leak valve, Knudsen cell, continuous adjustable iris, transition chamber, the family of power and influence, quadruple mass-spectrometer, temperature measurement system, temperature control system, pressure-measuring system and control pressurer system, it is characterized in that leak valve, Knudsen cell, continuous adjustable iris, transition chamber, the family of power and influence, aperture, mass spectrometer connect successively; But Knudsen cell is made of the sample lid of vertical movement, fixing removable sample cell, temperature and pressure Measurement and Control System.
2, Knudsen cell-mass spectrometer according to claim 1 is characterized in that utilizing the interface of leak valve as normal pressure and low pressure, and can control the gas flow that enters vacuum system; Utilize iris or leak to connect between Knudsen cell and the transition chamber, its aperture is adjustable continuously between 0-20mm; Utilize the family of power and influence to connect between transition chamber and the mass spectrometer, the vacuum tightness of mass spectrometer system is constant when guaranteeing to change sample.
3, Knudsen cell-mass spectrometer according to claim 1 is characterized in that sample lid can vertical movement, sample exposed or be isolated from the gas atmosphere, between sample lid and the sample stage with the sealing of O type circle.
4, Knudsen cell-mass spectrometer according to claim 1 is characterized in that all cavity inner surface plating Teflon films of Knudsen cell, has chemical inertness.
5, Knudsen cell-mass spectrometer according to claim 1 is characterized in that utilizing mass spectrum as detecting device, connects with aperture between the family of power and influence and the mass spectrometer detector, and its aperture is 10-20mm.
6, Knudsen cell-mass spectrometer according to claim 1 is characterized in that utilization circulates medium and realizes-60 ℃-0 ℃ and 0 ℃-250 ℃ respectively, the accurate control and the measurement of sample temperature, and its error range is ± 0.1 ℃.
7, pressure-measuring system according to claim 1 and control pressurer system, it is characterized in that Knudsen cell, transition chamber, mass spectrum vacuum chamber are connected with vacuum gauge respectively, the pressure of transition chamber and mass spectrum vacuum chamber is respectively by difference turbomolecular pump and turbomolecular pump and forepump control thereof.
8, sample stage according to claim 3 is characterized in that sample stage and Knudsen cell bottom constitutes a cavity, utilizes the circulation of heating or cooling medium to realize sample temperature is controlled.
9, sample stage according to claim 3 is buried platinum-resistance thermometer and is closely contacted with sample cell in it is characterized in that, its measurement range is-100 ℃-250 ℃, and measuring error is ± 0.1 ℃.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2007100994426A CN101311720A (en) | 2007-05-21 | 2007-05-21 | Knudsen Cell-mass spectrometer for gas adsorbing /desorption kinetic determination |
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| Application Number | Priority Date | Filing Date | Title |
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| CNA2007100994426A CN101311720A (en) | 2007-05-21 | 2007-05-21 | Knudsen Cell-mass spectrometer for gas adsorbing /desorption kinetic determination |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103592360A (en) * | 2013-10-21 | 2014-02-19 | 清华大学 | High-atmospheric-pressure differential extraction particle beam mass spectrum measurement system |
| CN104576289A (en) * | 2014-12-31 | 2015-04-29 | 聚光科技(杭州)股份有限公司 | Inductively coupled plasma mass spectrometer capable of regulating vacuum pressure |
| CN109742010A (en) * | 2018-11-23 | 2019-05-10 | 暨南大学 | Vacuum for vacuum instrument is into the method for varying |
| CN111201437A (en) * | 2017-10-13 | 2020-05-26 | 身体感官公司 | Fluid sensing device for portable electronic device |
| CN113970591A (en) * | 2020-07-22 | 2022-01-25 | 中国科学院大连化学物理研究所 | Ultra-high vacuum equipment-based combinable TPD system and use method |
-
2007
- 2007-05-21 CN CNA2007100994426A patent/CN101311720A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103592360A (en) * | 2013-10-21 | 2014-02-19 | 清华大学 | High-atmospheric-pressure differential extraction particle beam mass spectrum measurement system |
| CN103592360B (en) * | 2013-10-21 | 2016-09-21 | 清华大学 | Hyperbar differential extraction particle beam mass-spectrometer measurement system |
| CN104576289A (en) * | 2014-12-31 | 2015-04-29 | 聚光科技(杭州)股份有限公司 | Inductively coupled plasma mass spectrometer capable of regulating vacuum pressure |
| CN104576289B (en) * | 2014-12-31 | 2017-08-25 | 聚光科技(杭州)股份有限公司 | A kind of icp mses of adjustable vacuum pressure |
| CN111201437A (en) * | 2017-10-13 | 2020-05-26 | 身体感官公司 | Fluid sensing device for portable electronic device |
| CN109742010A (en) * | 2018-11-23 | 2019-05-10 | 暨南大学 | Vacuum for vacuum instrument is into the method for varying |
| CN109742010B (en) * | 2018-11-23 | 2021-03-23 | 暨南大学 | Vacuum sample feeding and changing method for vacuum instrument |
| CN113970591A (en) * | 2020-07-22 | 2022-01-25 | 中国科学院大连化学物理研究所 | Ultra-high vacuum equipment-based combinable TPD system and use method |
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Application publication date: 20081126 |