WO2014110699A1

WO2014110699A1 - Codirectional dual-channel time-of-flight mass spectrometer

Info

Publication number: WO2014110699A1
Application number: PCT/CN2013/000639
Authority: WO
Inventors: 秦正波; 唐紫超; 张世宇
Original assignee: 中国科学院大连化学物理研究所
Priority date: 2013-01-16
Filing date: 2013-05-30
Publication date: 2014-07-24
Also published as: CN103094051B; CN103094051A; RU2646860C2; RU2014146381A

Abstract

A codirectional dual-channel time-of-flight mass spectrometer. The mass spectrometer comprises parallel dual-channel accelerators (1), a miniature vacuum cavity (2), a laser sputtering ion source (3), two ion signal detectors (4, 5), and an ion collimator (6). Ion beams generated by the laser sputtering ion source (3) pass through the ion collimator (6) and are divided by the dual-channel accelerators (1) into an upper part and a lower part, and the two parts are respectively transversely accelerated, deflected, and focused to the two upper and lower ion signal detectors (4, 5); therefore, an ion time-of-flight mass spectrum of two upper and lower channels is obtained. One ion signal detector (4) can be replaced by an electron energy analyzer, to carry out a photoelectron energy spectrum experiment for selecting a certain ion at the same time. The whole instrument is compact, small and exquisite, simple in structure, and convenient to operate. The electron energy spectrum of the acquired ion has a high signal to noise ratio and a high resolution.

Description

Description A co-directional two-channel time-of-flight mass spectrometer

Technical field

The invention relates to the field of cascade time-of-flight mass spectrometry, and in particular to a co-directional dual-channel time-of-flight mass spectrometer.

Background technique

The time-of-flight mass spectrometer is an instrument for recording molecular mass-to-mass ratio. According to the information provided by the mass spectrometer, qualitative and quantitative analysis of various organic and inorganic substances, structural analysis of complex compounds, determination of various isotope ratios in samples, and solid surface can be performed. Structure and composition analysis, etc. Photoelectron spectroscopy (or photoelectron imaging) is a UV laser that irradiates molecules or ions, and the photoelectron velocity is recorded to reflect the electrons, vibrations, or rotational energy levels and structure types of the molecular orbitals. Time-of-flight mass spectrometry Since 1955, W. C. Wiley and I. H. McLaren (Rev. Sci. Instrum. 26, 1150 (1955)) have developed rapidly using dual-field acceleration techniques and have important applications in many fields. The combination of time-of-flight mass spectrometry and photoelectron spectroscopy (or photoelectron imaging) can study the structure and properties of complex compounds, and is of great significance for the study of molecular electronic energy levels and even vibration and rotational energy levels. Time-of-flight mass spectrometry - Photoelectron spectroscopy (or photoelectron imaging) Composite spectroscopy plays a key role in the research of organic molecules, free radicals, and clusters.

In this conventional time-of-flight mass spectrometry-photoelectron spectroscopy (or photoelectron imaging) technique, the electrode plate of the accelerator uses a single-hole metal grid to transport ions. The ion signal detector is located at a certain distance from the accelerator, which we call " Focus point." The flight time of different ions can be separated. We detect the same time The arriving ion signals are ion signals of the same mass. But it has a fatal weakness: when coupling photoelectron spectroscopy (or photoelectron imaging) theoretically needs to be placed at that "focus point", it will actually conflict with the ion signal detector. Often many research groups in the world (Rev. Sci. Instrum. 77, 123901 (2006); Rev. Sci. Instrum. 70, 1957 (1999); J. Phys. Chem. A 2003, 107, 8215-8224; Chin. J. Chem. Phys. 23, 373 (2010); Chin. J. Chem, Phys. 22, 655 (2009).) is the practice of placing photoelectron spectroscopy (or photoelectron imaging) at a distance from the "focus point" The place (usually 5-20 cm) is called the "probe area". According to the two-field acceleration principle, in this detection zone, the time distribution and spatial distribution of ions are scattered relative to the "focus point". This leads to the following weaknesses: In the pulse working mode, especially when using nanosecond laser to irradiate the ions of the "detection zone", good time focusing and spatial focusing characteristics are needed. However, in the "probe area", since the time is more than twice as wide as the "focus point" and the spatial ion distribution volume is increased by at least 8 times, the unit volume ion of the "probe area" is compared to the "focus point". Its intensity is weak by at least an order of magnitude, thereby reducing acquisition efficiency, signal-to-noise ratio of electronic signals, and resolution of electron energy.

Summary of the invention

In order to overcome the deficiencies of the prior art, it is an object of the present invention to provide a co-directional two-channel time-of-flight mass spectrometer.

The invention provides a co-directional two-channel time-of-flight mass spectrometer, which is compact and compact, and includes a parallel two-channel accelerator (1), a small vacuum chamber (2), a laser sputtering ion source (3), an ion signal. Detector (4), (5) and ion collimator (6); ion collimation 13 000639

3

(6) The small vacuum chamber (2) is divided into two parts, and a laser sputter ion source (3) is installed 5 cm directly above the sub-collimator (6), and is installed vertically 10 cm directly below the collimator. A set of parallel two-channel accelerators (1), wherein the laser sputter ion source (3) exit, the ion collimator (6) hole center, and the dual channel accelerator (1) are at the same centerline axis. Two ion signal detectors (4) and (5) are placed at 43.5 cm to the right of this central axis, respectively, for detecting the ion time-of-flight mass spectra of the upper and lower channels.

The same-direction dual-channel time-of-flight mass spectrometer provided by the invention, the laser sputtering ion source (3) irradiates the laser plasma generated by the metal target surface with the laser, and then the ion complex generated by the action of the ultrasonic molecular beam is ejected through the nozzle. The ion beam passes through the ion collimator (6) and flies for a period of time into the center of the two-channel accelerator (1). Since the ion beam has a certain length in the flight path, the ion beam is taken up by the upper and lower channels of the accelerator (the diameter of the hole is 1.6 cm, The spacing of 4.5 cm) is divided into two segments, and is accelerated laterally, deflected, and focused to the ion signal detectors (4) and (5) for detection. Finally, the ion time-of-flight mass spectra of the upper and lower channels are recorded.

The invention provides a co-directional two-channel time-of-flight mass spectrometer, the laser sputtering ion source

(3) A pulsed laser ultrasonic molecular beam negative ion source is used. The electrode plate of the two-channel accelerator (1) adopts a double hole and a grid, two upper and lower parallel deflection plates, and two upper and lower parallel ion lenses.

The same-direction dual-channel time-of-flight mass spectrometer provided by the invention adopts the same pulse accelerating voltage when the parallel two-channel accelerator (1) is used in both upper and lower sections, and the ion signal detectors (4) and (5) detect the same pole. Sex ion signal. When parallel dual channel accelerators (1) The upper and lower holes adopt positive and negative pulse acceleration voltages respectively, and the ion signal detectors (4) and (5) detect ion signals of opposite polarity.

The invention provides a co-directional two-channel time-of-flight mass spectrometer, which is small in size and simple in structure.

The present invention provides a co-directional two-channel time-of-flight mass spectrometer that can be used to couple other spectroscopy instruments for multi-task parallel operation. For example, the mass spectrometer is coupled with the photoelectron spectrum; the ion signal detector (4) coupled above is replaced by an electron spectrometer or a photoelectron imager (7) (as shown in Figure 3), and a single mass can be performed. The electron energy spectrum of the ion is measured, and the ion signal detector (5) below can simultaneously detect the ion signal. This coupling method allows us to perform the ion spectrum detection while collecting the energy spectrum of a certain mass of ions.

The same-direction dual-channel time-of-flight mass spectrometer provided by the invention, when the electron energy spectrum of an ion is measured by the upper channel electron energy spectrometer (7), the laser light-emitting time is equal to that of the lower channel detector (4). Ion time-of-flight mass spectrometry plus a time constant (which is the circuit delay inside the irradiated laser, typically a few hundred nanoseconds).

In the present invention, the photoelectron spectrometer is at the "focus point" of the upper channel time-of-flight mass spectrometer, and the "probe area" is also the "focus point". When pulsed laser irradiation is applied to the "focus point" ions, the ionic strength is at least one order of magnitude higher than that of the conventional time-of-flight mass spectrometry "detection zone", which improves the signal collection efficiency and improves the signal-to-noise of the electronic signal. Ratio and resolution of electron energy.

DRAWINGS

Figure 1 (a) shows the structure of a single-hole accelerator used in traditional time-of-flight mass spectrometry. (b) A schematic diagram of the structure of a two-hole accelerator used in the same-direction two-channel time-of-flight mass spectrometer of the present invention;

2 is a general structural view of a co-directional two-channel time-of-flight mass spectrometer of the present invention; FIG. 3 is a general structural view of a coupled photoelectron spectrometer (or photoelectron imager) of the same-direction dual-channel time-of-flight mass spectrometer;

Figure 4 is a mass spectrum of the reaction of gold and iodine anion collected in the lower channel time-of-flight mass spectrometer with water;

Figure 5 is a time-of-flight mass spectrum based on the reaction of gold and iodine anion with water. The photoelectron spectrum of each mass spectrum peak is obtained on the upper channel.

detailed description

The present invention will be further described in detail below with reference to the drawings and embodiments, and the embodiments of the present invention are not limited to the following description. It will be apparent to those skilled in the art that the present invention can be made without departing from the spirit and scope of the invention.

In this embodiment, the accelerator electrode plate is processed by double holes and attached to the metal grid as shown in (1 b). In the diagram (2), the accelerator (1) adopts the electrode plate structure in the figure (1 b), and two sets of deflection plates are used, and two sets of ion lenses are used. The ion signal detectors (4) and (5) are placed at the upper and lower "focus points", respectively, for mass spectrometry analysis. When the parallel two-channel accelerator (1) uses the same pulse acceleration voltage in both the upper and lower sections, the ion signal detectors (4) and (5) detect the same polarity ion signals; when the parallel two-channel accelerator (1) The upper and lower holes adopt positive and negative pulse acceleration voltages respectively, and the ion signal detectors (4) and (5) detect ion signals of opposite polarity. In this embodiment, electron energy spectrum measurement of ions can be performed when the ion signal detector (4) is replaced by a photoelectron spectrometer (or photoelectron imager) (7) as shown in (3). The whole workflow is: the negative ion beam generated by the ion source is divided into upper and lower parts by the two-channel time-of-flight mass analyzer through the collimator, and is respectively accelerated laterally, deflected, and focused to reach the upper and lower "focus points", and the lower channel is placed. The detector (5) records ion time-of-flight mass spectrometry. According to the mass spectrum, the time-of-flight T _f of the ion M to be detected by the photoelectron spectrum is selected, and the light-emitting time of the pulsed laser irradiation is determined by the formula T _ft =T _f -T _aw (T _aw is the internal circuit delay of the laser, which is a fixed value. , determined by photodetector in advance: 0.22 microseconds), so that we can conveniently and quickly locate the pulsed laser light extraction time to accurately irradiate all the ions in the mass spectrometer, and to detect the photoelectron spectrum signals of all ions without deviation. As shown

(4) is a mass spectrum of gold and iodine anion recorded in the lower channel in Fig. 3 and water. From the spectrum, you can see a single mass peak (gold and iodine anion), as well as complex multi-mass peaks such as AuO', Au(OH)", Au'(H ₂ 0). (5) is the photoelectron spectrum obtained under the same ion source experimental conditions with the same number of signal accumulation times.

(5a) is a photoelectron spectroscopy of Αιι·(Η ₂ 0) collected by a conventional photoelectron imaging apparatus (Chin. J. Chem. Phys. 23, 373 (2010)), Fig. (5b) and Fig. (5c) The photoelectron spectroscopy of A (H ₂ 0) and ΑυΟ· is collected by the instrument of the present invention, and the electronic energy level information and the vibration peak characteristic of each mass spectrum peak are reflected. Comparison chart (5a) and figure

(5b), and Fig. (5c) The present invention increases the signal intensity by about 5 times, and the noise-to-noise ratio is improved (ΑιΓ(3⁄40), and the small vibration peak to the right of the AuO' main peak can be clearly detected).

The invention can be applied to the field of mass spectrometry, and the ion beam generated by the ion source is divided into upper and lower parts by a two-channel time-of-flight mass analyzer, and is respectively accelerated laterally. Deflection, focus to the upper and lower detectors, record the ion flight time. The whole set of instruments is compact and compact, the structure is simple, the operation is convenient, the obtained electron energy spectrum of the ion spectrum is 信, and the resolution is 髙.

Claims

claims

1. A co-directional dual-channel time-of-flight mass spectrometer, characterized by: The mass spectrometer is compact and small, including a parallel dual-channel accelerator (1), a small vacuum cavity (2), a laser sputtering ion source (3), Ion signal detectors (4), (5) and ion collimators (6);

The ion collimator (6) divides the small vacuum chamber (2) into two parts. The laser sputtering ion source (3) is located above the ion collimator (6), and the parallel dual-channel accelerator (1) is located at the ion collimator. Below the collimator (6); the outlet of the laser sputtering ion source (3), the center of the hole of the ion collimator (6) and the midpoint of the two accelerating sheets of the dual-channel accelerator (1) are on the same centerline axis; the ion signal detector ( 4) and (5) are respectively located on the left and right of this central axis.

2. The co-directional dual-channel time-of-flight mass spectrometer according to claim 1, characterized in that: the laser sputtering ion source (3) generates laser plasma by irradiating the metal target surface with laser, and then reacts with the ultrasonic molecular beam to generate ions The complex is ejected through the nozzle, and the ion beam flies for a period of time after passing through the ion collimator (6) and enters the center of the dual-channel accelerator (1). Since the ion beam has a certain length on the flight path, the ion beam is moved by the upper and lower sides of the accelerator. Each channel is divided into two sections, and are respectively laterally accelerated, deflected, and focused to the ion signal detectors (4) and (5) for detection. The final record is the ion time-of-flight mass spectrum of the upper and lower channels.

3. The co-directional dual-channel time-of-flight mass spectrometer according to claim 1 or 2, characterized in that: the laser sputtering ion source (3) adopts a pulsed laser ultrasonic molecular beam negative ion source.

4. The co-directional dual-channel time-of-flight mass spectrometer according to claim 1 or 2, characterized in that: the electrode plate of the dual-channel accelerator (1) adopts double holes and is attached to a grid, and there are two parallel sets of upper and lower deflection plates, Two sets of parallel ion lenses, upper and lower.

5. The co-directional dual-channel time-of-flight mass spectrometer according to claim 1 or 2, characterized in that: when the upper and lower sections of the parallel dual-channel accelerator (1) adopt the same pulse acceleration voltage, the ion signal detector (4) and (5) All detected ion signals are of the same polarity.

6. The co-directional dual-channel time-of-flight mass spectrometer according to claim 1 or 2, characterized in that: when the parallel dual-channel accelerator (1) uses positive and negative pulse acceleration voltages in the upper and lower holes respectively, the ion signal detector (4) And (5) detects ion signals of opposite polarity.

7. The co-directional dual-channel time-of-flight mass spectrometer according to claim 1 or 2, characterized in that the mass spectrometer can be used to couple other spectroscopic instruments to perform multi-task parallel operations.

8. The co-directional dual-channel time-of-flight mass spectrometer according to claim 7, characterized in that: the mass spectrometer is coupled to the photoelectron spectrometer; the coupling mode is that the upper ion signal detector (4) is connected to the electron spectrometer or ( 7) is replaced by a photoelectron imager to measure the electronic energy spectrum of a single mass ion, while the ion signal detector (5) below detects the ion signal at the same time. This coupling method allows the ion signal to be detected and a certain mass to be detected at the same time. Energy spectrum collection of ions.

9. The co-directional dual-channel time-of-flight mass spectrometer according to claim 8, characterized in that: when the electron spectrum of a certain ion is measured by the upper channel electron spectrometer (7), the laser light emission time is equal to the lower channel detection The instrument (5) measures the time-of-flight mass spectrum of a certain ion and adds a time constant.

10. The co-directional dual-channel time-of-flight mass spectrometer according to claim 9, characterized in that Yu: The time constant described is the circuit delay inside the irradiation laser, which is generally several hundred nanoseconds.