CN214895012U - Cross molecular beam detector capable of eliminating interference of reactant background signal - Google Patents

Abstract

The utility model relates to a cross molecular beam detection device capable of eliminating interference of reactant background signals. The device consists of a main chamber, a detection chamber and an ion detection module. The main chamber consists of a reaction chamber and a rotating beam source chamber and is used for providing a place for triggering the elementary chemical reaction; the detection chamber consists of two differential pumping chambers and provides a photoionization environment without interference of reactant background signals for product detection; the ion detection module consists of a micro-channel plate, an electronic receiver, a signal amplifier and an acquisition card and is used for measuring the time flight spectrum of the ionized product. The utility model discloses a move the light ionization region from reaction center to the detection area front end, utilize the difference of two levels to take out and keep apart the reactant outside the detection area, fundamentally eliminates the reactant because of the background signal interference that the detection laser effect introduced, combines together with time flight spectrum technique through the laser light ionization technique to the realization is to the measurement of the high sensitivity of the result time flight spectrum of elementary chemical reaction, high resolution.

Description

Cross molecular beam detector capable of eliminating interference of reactant background signal

Technical Field

The utility model relates to a cross molecular beam detection device, in particular to a cross molecular beam detection device which can eliminate the interference of reactant background signals.

Background

The cross molecular beam technology is an important tool for realizing the elementary chemical reaction research of quantum state resolution in modern physical chemistry experimental research. The so-called cross molecular beam technique is to make two molecular beam sources perform single collision under a high vacuum environment at a certain angle, and then elastic/inelastic scattering or chemical reaction process occurs. In the specific experimental research process, how to obtain kinetic information such as energy distribution, product space distribution and the like of the elementary chemical reaction is the key point of the cross molecular beam experimental research.

In the past, devices for detecting elementary chemical reaction products were "universal" cross-molecular-beam experimental devices based on electron bombardment detection technology. The device ionizes products reaching an ionization region by an electron bombardment method, and then mass screening and collecting product ions by a mass spectrum detector to obtain a product time flight spectrum. Because the detection efficiency of electron bombardment is low, residual gas in a detection chamber is often ionized simultaneously to generate a strong background signal, and the resolution of a mass spectrum detector is not satisfactory, the device is wide in application but not suitable for high-resolution elementary chemical reaction research.

The ion velocity imaging technology developed in recent years uses laser photoionization to detect the products. The technology is characterized in that laser is applied to a reaction center, so that products flying towards all directions are subjected to photoionization, product ions with the same velocity vector at different positions are focused on the same point on a detection plane by combining an ion lens, and finally, the information of the velocity distribution and the spatial angular distribution of the products is obtained. Although the technology improves the detection sensitivity, on one hand, reactants and products are gathered at the reaction center, and if the reactants can be photolyzed by laser light, the same fragments as the products can be photoionized by the same laser light at the same time, and then background signals interfering with the product signals are generated; on the other hand, the space focusing effect of the ions is deteriorated due to the charge repulsion effect existing between the charged particles in the time period when the ions fly from the reaction center to the detection plane, and the final detection resolution is further influenced.

Disclosure of Invention

To the above-mentioned weak point that exists among the prior art, the to-be-solved technical problem of the utility model is to provide a can eliminate cross molecular beam detection device of high-sensitivity high-resolution of reactant background signal interference.

The utility model discloses a realize that the technical scheme that above-mentioned purpose adopted is:

the device in the utility model comprises a main chamber, a detection chamber and an ion detection module.

The main chamber consists of a reaction chamber, a first rotating beam source chamber and a second rotating beam source chamber and is used for providing a laboratory site for triggering elementary chemical reactions, and the reaction chamber, the first rotating beam source chamber and the second rotating beam source chamber are independently vacuumized;

the first rotating beam source chamber and the second rotating beam source chamber are fixed on a rotating disc, the rotating disc is in dynamic sealing connection with the reaction chamber, the two rotating beam source chambers can integrally rotate around a central shaft of the reaction chamber, a pulse valve is arranged in each of the first rotating beam source chamber and the second rotating beam source chamber and used for preparing a reactant beam source, and the two reactant beam sources trigger chemical reaction at the central position of the reaction chamber due to collision.

The detection chamber consists of a first differential pumping chamber and a second differential pumping chamber, and the first differential pumping chamber is in static sealing connection with the reaction chamber and is respectively and independently pumped into vacuum in order to provide a high vacuum environment for photoionization detection products;

the two differential pumping chambers and the first differential pumping chamber are communicated with the reaction chamber through the colanders, a product generated at the central position of the reaction chamber sequentially enters the second differential pumping chamber through the two colanders to realize the separation of a reactant and the product in a detection region, and the product is ionized into ions by laser light introduced into the second differential pumping chamber when the product is close to the front end of the detection region; the first differential pumping chamber and the second differential pumping chamber are both provided with a vacuum gauge for detecting the vacuum degree in the cavity, and the second differential pumping chamber is provided with a residual gas analyzer for monitoring the residual concentration of the reactant molecules in the detection region; and a light shielding cylinder is additionally arranged inside and outside the second differential pumping chamber along the optical axis direction.

The ion detection module consists of a micro-channel plate, an electronic receiver, a signal amplifier and a collection card and is used for detecting the time flight spectrum of the ionized product;

the ionized product impacts the micro-channel plate along the original flight direction to generate secondary electrons, the electrons are multiplied by the voltage applied to two ends of the micro-channel plate, the electrons coming out of the micro-channel plate are collected by an electron receiver at the rear end, the electrons are amplified by a signal amplifier, the flight time and the intensity information of the signals are recorded by an acquisition card, and finally, the time flight spectrum of the product is obtained.

Preferably, the colander is an ultrathin conical collimator made of nickel, the front end of the colander is provided with a small hole, and three points and one line are formed between the circle centers of the small holes of the two colanders and the reaction center.

Preferably, the rotating disc and the reaction chamber are in dynamic sealing connection through a bearing and a sealing ring.

Preferably, the first differential pumping chamber is in static sealing connection with the reaction chamber through a rubber ring.

The utility model discloses following beneficial effect has: the utility model moves the laser photoionization area to the front end of the detection area, and effectively isolates the product from the reactant by combining a two-stage differential pumping mode, thereby fundamentally eliminating the interference of fragment signals generated by the laser photoionization reactant on the product signals and enabling the device to have more universality; meanwhile, the laser ionization technology is taken as an ionization means in the process of detecting the product by the time flight spectrum technology, so that the advantages of the two technologies are taken into consideration, and the device has high sensitivity and high resolution performance.

Drawings

Fig. 1 is a schematic view of the structure of the device of the present invention.

The device comprises a reaction chamber 1, a first rotating beam source chamber 2, a first rotating beam source chamber 3, a second rotating beam source chamber 4, a rotating disc 5, a pulse valve 6, a first differential pumping chamber 7, a second differential pumping chamber 8, a strainer 9, a laser 10, a light shielding cylinder 11, a microchannel plate 12, an electronic receiver 13, a signal amplifier 14 and an acquisition card.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples.

As shown in fig. 1, the present embodiment comprises a main chamber, a detection chamber and an ion detection module.

The main chamber consists of a reaction chamber 1, a first rotating beam source chamber 2 and a second rotating beam source chamber 3 and is used for providing a laboratory site for triggering elementary chemical reactions, each chamber is independently vacuumized, the first rotating beam source chamber 2 and the second rotating beam source chamber 3 are fixed on a rotating disc 4, the rotating disc 4 is in dynamic sealing connection with the reaction chamber 1 through a bearing and a sealing ring, the two rotating beam source chambers can integrally rotate around the central shaft of the reaction chamber 1, a pulse valve 5 is respectively arranged in the first rotating beam source chamber 2 and the second rotating beam source chamber 3 and is used for preparing reactant beam sources, and the two reactant beam sources trigger chemical reactions at the central position of the reaction chamber 1 due to collision.

The detection chamber consists of a first differential pumping chamber 6 and a second differential pumping chamber 7, in order to realize that the photoionization detection product provides a high vacuum environment, the first differential pumping chamber 6 is in static sealing connection with the reaction chamber 1 through a rubber ring, the two differential pumping chambers are respectively and independently pumped vacuum, the first differential pumping chamber 6 and the reaction chamber 1 are communicated through a strainer 8, the center position of the reaction chamber 1, namely, the product generated at the reaction center enters the second differential pumping chamber 7 through the two colanders 8 in turn to realize the separation of the reactant and the product in the detection area, the product is photoionized into ions by the laser 9 introduced into the second differential pumping chamber 7 when the product is close to the front end of the detection area, in order to reduce the influence of stray light generated by laser light at the light inlet and the light outlet or in the propagation direction on the microchannel plate 11, a light shielding cylinder 10 is additionally arranged inside and outside the second differential pumping chamber along the optical axis direction.

The ion detection module is composed of a microchannel plate 11, an electron receiver 12, a signal amplifier 13 and an acquisition card 14 and is used for detecting a time flight spectrum of ionized products, the ionized products impact the microchannel plate 11 along the original flight direction to generate secondary electrons, the secondary electrons are accelerated by voltage applied to two ends of the microchannel plate 11 to realize electron multiplication, electrons coming out of the microchannel plate 11 are collected by the electron receiver 12 at the rear end, the electrons are amplified by the signal amplifier 13, the flight time and intensity information of the signals are recorded by the acquisition card 14, and finally the time flight spectrum of the products is obtained.

The colander 8 is an ultrathin conical collimator made of nickel, a small hole is formed in the front end of the colander, and three points and one line are formed between the circle centers of the small holes of the two colanders 8 and the reaction center.

The laser 9 is continuous light, and the wavelength of the continuous light can be tuned according to the ionization energy of the detected product, so that the soft ionization detection of the product is realized.

The acquisition card 14 has a time resolution function, and can effectively distinguish and record signals arriving at different time periods.

The first differential pumping chamber 6 and the second differential pumping chamber 7 are both provided with a vacuum gauge for detecting the vacuum degree in the chamber, and the second differential pumping chamber 7 is provided with a residual gas analyzer for monitoring the residual concentration of the reactant molecules in the detection region.

The method for realizing the high-sensitivity high-resolution cross molecular beam detection for eliminating the interference of the reactant background signal by using the device comprises the following steps:

the elementary chemical reaction product under a certain angle generated by mutual collision of reactant beam sources at the center of the reaction chamber 1 continuously passes through the colanders 8 on the first differential pumping chamber 6 and the second differential pumping chamber 7, and is effectively separated from the reactant, the product is subjected to photoionization under the action of the laser 9 when reaching the front end of the detection area, the ions continuously fly to the microchannel plate 11 and generate secondary electrons by impacting the microchannel plate 11, the electrons are collected by the electron receiver 12 at the rear end and realize signal gain through the signal amplifier 13, and finally the time and intensity information of the product flying from the reaction center to the microchannel plate 11 is recorded by the acquisition card 14, so that the time flight spectrum of the product under the angle is obtained. In the whole detection process, the product is purified through two-stage differential extraction, the background signal interference generated by the action of laser on a reactant is eliminated, laser photoionization is used as an ionization means in the process of detecting the product by the time flight spectrum, and the advantages of high sensitivity of the product and high resolution of the time flight spectrum technology are taken into account. In order to further acquire the product time flight spectrum under different flight directions, the relative detection angle of the ion detection module can be changed by rotating the rotating disc 4, but the rotation angle needs to ensure that the emergent direction of the reactant beam source and the detection direction are not always on the same straight line.

The utility model discloses a concrete implementation operation process as follows:

1. assembling the components of the device according to fig. 1, adjusting the angle between the two rotating beam source chambers, and moving the laser into a second differential pumping chamber;

2. starting a vacuum pump to enable the vacuum degree of each cavity to reach ultimate vacuum, and loading voltages at two ends of the microchannel plate;

3. opening a pulse valve to trigger elementary chemical reaction;

4. when the product sequentially passes through the colander and reaches the front end of the detection region, the product meets the laser and then generates photoionization;

5. the ionized product impacts the micro-channel plate to generate secondary electrons, and gain and amplify under the action of high pressure;

6. the electrons are collected by the electronic receiver and amplified by the signal amplifier, and then accumulated and output by the acquisition card.

Claims (4)

1. The cross molecular beam detection device capable of eliminating the interference of reactant background signals is characterized by comprising a main chamber, a detection chamber and an ion detection module;

the main chamber consists of a reaction chamber (1), a first rotating beam source chamber (2) and a second rotating beam source chamber (3) and is used for providing a laboratory site for triggering elementary chemical reactions, and the reaction chamber (1), the first rotating beam source chamber (2) and the second rotating beam source chamber (3) are independently vacuumized;

the first rotating beam source chamber (2) and the second rotating beam source chamber (3) are fixed on a rotating disc (4), the rotating disc (4) is in dynamic sealing connection with the reaction chamber (1), the two rotating beam source chambers can integrally rotate around the central shaft of the reaction chamber (1), a pulse valve (5) is respectively arranged in the first rotating beam source chamber (2) and the second rotating beam source chamber (3) and used for preparing a reactant beam source, and the two reactant beam sources trigger chemical reaction at the central position of the reaction chamber (1) due to collision;

the detection chamber consists of a first differential pumping chamber (6) and a second differential pumping chamber (7), wherein the first differential pumping chamber (6) is in static sealing connection with the reaction chamber (1), and the two differential pumping chambers are respectively and independently pumped;

the two differential pumping chambers and the first differential pumping chamber (6) and the reaction chamber (1) are communicated through a strainer (8), and products generated at the central position of the reaction chamber (1) sequentially pass through the two strainers (8) and enter a second differential pumping chamber (7), so that the separation of reactants and the products in a detection area is realized; the product is photoionized into ions by laser (9) introduced into a second differential pumping chamber (7) while approaching the front end of the detection region; the first differential pumping chamber (6) and the second differential pumping chamber (7) are both provided with a vacuum gauge for detecting the vacuum degree in the cavity, and the second differential pumping chamber (7) is also provided with a residual gas analyzer for monitoring the residual concentration of the reactant molecules in the detection area; a light shielding cylinder (10) is additionally arranged inside and outside the second differential pumping chamber (7) along the optical axis direction;

the ion detection module consists of a micro-channel plate (11), an electronic receiver (12), a signal amplifier (13) and an acquisition card (14) and is used for detecting a time flight spectrum after ionization of a product;

the ionized product impacts the microchannel plate (11) along the original flight direction to generate secondary electrons, the secondary electrons are accelerated by the voltage applied to two ends of the microchannel plate (11) to realize electron multiplication, the electrons coming out of the microchannel plate (11) are collected by an electron receiver (12) at the rear end, the flight time and the intensity information of the ion signals are recorded by an acquisition card (14) after the electrons are amplified by a signal amplifier (13), and finally, the time flight spectrum of the product is obtained.

2. The device for detecting cross molecular beams capable of eliminating interference of reactant background signals as claimed in claim 1, wherein the colander (8) is an ultrathin conical collimator made of nickel, a small hole is formed at the front end of the colander, and three points and a line are formed between the centers of the small holes of the two colanders (8) and the reaction center.

3. The apparatus for detecting cross molecular beam capable of eliminating interference of background signal of reactant according to claim 1, wherein the rotating disc (4) is in dynamic sealing engagement with the reaction chamber (1) through a bearing and a sealing ring.

4. The apparatus according to claim 1, wherein the first differential pumping chamber (6) is in static sealing engagement with the reaction chamber (1) via a rubber ring.

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