SU1005216A1 - Time-of-flight mass spectrometer - Google Patents

Description

(54) TIME-PRELATED MASS SPECTROMETER

The invention relates to a dynamic mass spectrometry and is used to study the effects of laser radiation on gas jet molecules.

 The most interesting effects of laser radiation on molecules are the multiphoton absorption and dissociation of molecules. They occur at maximum electromagnetic field densities, which are achieved only in a pulsed laser mode. In a number of cases, preliminary cooling of the studied molecules is required, which is carried out in an expanding gas jet. The pulsed nature of the process and the need to feed a bratz gas in the form of a gas jet extremely complicate the task of mass spectrometric analysis of interaction products.

Used for these purposes, mass spectrometers with a stable path of movement of ions 11 have a limited range of measured masses and allow for the analysis of the amount of only one mass component per laser pulse. Therefore, in order to obtain several mass spectra, it is necessary to repeat the measurements several times, which leads to an increase in the error due to the instability of the laser and gas jet operation, a significant increase in the Eno10 period, and an increase in the sample size.

Products, pulsed in a small volume of interaction of laser radiation with jet molecules,

JS is convenient to analyze using the time-of-flight mass spectrometer. It produces a single pulse of laser boaneftstv and obtains the entire mass spectrum of interaction products.

20

For the rapid analysis of products of interaction with a transit mass spectrometer and for an effective transfer of excited molecules during transporting and its oscillations, it is known to impregnate the gas stream with laser light directly on the ion source ionization time, containing imputric radiation, which is imputable, and impersonal irradiation of the ion source ion is known. the receiver of ions, the ION Source of such a device contains several electrode-accelerating ions, located paraplelically, and an electron gun placed so that the electron beam passes between these electrodes parallel to them. G21 .... However, the simultaneous output of a gas jet and laser radiation to this ion source is not feasible, which means it is impossible to ensure the study of the interaction of laser radiation with jet molecules. The closest to the invention is the transit mass spectrometer containing a pulsed ion source, drift space and ion detector The ion source includes two electrodes, which limit the ionization region, and an electron gun with an electron collector, positioned so that: ktronov pairs of alleles to electrodes t.). The disadvantage of this 1X instrument is the impossibility of examining with it the effect of laser radiation on the ytrui molecule. This is due to the fact that the ionization region of the ion source is bounded on four sides by two electrodes, an electron gun, and an electron collector. Thus, the simultaneous introduction of a gas jet and a laser radiation of the NCW into this volume of the cross-secacquix does not & oz south; but. The goal of izofeteniya is to expand the functionality by studying the processes of laser irradiation of the gas jet molecules using the time-of-flight mass spectrometer. The goal is achieved by the fact that during a time-of-flight mass spectrometer, including a pulsed ion source with an electron gun and two limited ionization areas with electrodes, a drift space and a pickup of ions, a slotted torus was introduced into the ion source: a torus of gas jet, two quantum generators and two diaphragm ion sources located on opposite sides for inputting radiation from quantum generators, made movable, the collimator being located in a plane perpendicular to the plane electrodes that limit the ionization region, the middle plane of the gas jet lies between the indicated electrodes, the optical axes of the quantum generators, the passage of the PGay through the centers of the diaphragms: they coincide and lie in the middle plane of the gas jet, the electron gun is located behind the first electrode, which bounds the ionization region a slit for the passage of the electron beam, and the second electrode is made with a slit for the passage of ions from the ionization region, and the slits in both electrons are parallel flax laser axis. A slit collimator is required to introduce a gas jet into the ionization region between the electrodes of the ion source of the gas. So that it passes without touching the design elements of the source. The two diaphragms of the laser beams are used to introduce laser radiation into the ionization region between the electrodes of the ion source, so that the laser beams cross the middle plane of the gas jet and do not touch these electrodes. The arrangement of the electron gun so that the electron beam passes between the limited region of ionization by the electrodes parallel to them (as in the prototype and the transient mass spectrometer) is now constructively impossible. Therefore, it is placed behind the first electrode that limits the ionization region, and this electrode is made with a slit for the passage of the tron beam to the ionization region. The angle of inclination of the plane of the electron beam to the plane of the first electrode can be almost any non-zero. Preferred angles close to 45, since an increase in the angle of inclination leads to a broadening of the packet of ions, cut out (from all iovized molecules) by the slit of the second O | e, which, in turn, reduces the resolution of the mass spectrometer. A decrease in this diameter leads X to a constructive increase in the distance 6 and 9 to the ionization zone and practically reduces the current to the current, which reduces the sensitivity of the device. The interaction zone of a gas emulsion in laser radiation is a kind of cylindrical volume formed by the intersection of the laser beams and a gas jet. in order to ensure miimimum sensitivity, the time of the passing mass spectrometer is necessary to ensure the maximum overlap of this pilindrical ribbon-volume. ns electron beam. This is achieved by the fact that the slit in the first electrode is parallel to the axis of the lindrical volume, and the electron gun is positioned so that the ribbon electron beam passes through this slit and crosses the axis of the cylindrical volume. To pass the ion of the irradiated molecules into the drift space in the second electrode bounding the ionization region, a slit is cut, the axis of which is parallel to the axis of the laser beams. At the same time, the majority of the ions obtained from the molecules of the jet stream, not irradiated by laser light, do not pass into the gap of the second electrode. To increase the electron density of the NON Current, which leads to an increase in the sensitivity of the mass spectrometer, several electron guns located by the first electrode can be used in the ion source so that the planes of the ribbon electron beams intersect with the axis parallel to the axis of the laser beams. In this case, several necks are cut in the first electrode. FIG. 1 is a block diagram of the time of the flow-through mass spectrometer; in fig. 2 - ion source design The proposed device consists of. from the pulsed ion source 1, the drift space 2 and the receiver 3 ion. The ion source is a slit collimator 4, which forms a gas jet with two diaphragms 5 and 6 of laser beams. The electron guns 7 and 8 are located behind the first ionization region of the electrode 9, in which two slots 10 and 11 are cut for the passage of the ribbon electron beams. In the second electrode 12, a slit 13 is made for the passage of ions from the duct of the device. The device operates as follows. In the region of ionization between the electrodes d and 12 through a slotted koplnmator 4 gets tape jet of the test gas. At the determined moment of time, a certain part of this jet (determined by the position of the diaphragms of the laser beams 5 and 6) is irradiated by a pulse of laser light. Then the same section of the gas jet was irradiated by electron beams from the guns 7 and 8. The puffed out ions ejected from the electron beam by the pulsed voltage applied to the electrodes 9 and 12 were connected to the circuit. space 2. Ions can be released from the residual gas and scattered gas jet molecules throughout the junction of the ribbon electron beams, through the slit 12 in the second electrode that limits the ionization region 12, predominantly containing ions in the gas jet zone. The ions that pass into the / feyfovoy space 2 are separated by masses and consecutively received. on the receiver 3 ions. PRI me R. An ellp was created for a time-of-flight mass spectrometer to study the processes of laser irradiation on the gas jet molecules. In the ion source of this device, three accelerating electrode ions (fjfe nof amplification resolution, mass spectrometer) are used, two of which limit the ionization region. The dimensions of these electrodes are 6O ZO v2 mm. The distance between the electrodes, which limit the area of ionisation, is 5 mm for the uninterrupted passage of laser beams and a gas jet. The slit collimator has a size of 1 slit 1 Х1О forms a gas jet, the middle plane of which is parallel to the accelerating ions electrons. The diaphragm and grain of the rays have an oTBej diameter of 1 mm and are set so that the rays intersect the gas stream at an angle of EO and lie in its middle plane. I. At the ion source; Two electron guns with electrostatic focusing were placed, which made it possible to create an apegron current density of about 2 mA / cm in the ionization region. The cross section of each electron beam has dimensions of 1–12 mm. The planes of the electron beams are located under angle 45 to the plane of the electrode bounding the ionization electrode, in which the axis is. One hundred mm 5 mm bar of an ogg cut inclined slots 1x12 mm in size for the passage of electric beams. In the second, limited HotinaaiiOTi area, the electrode is filled with a slit (1). 10 mm for the removal of ions from the irradiated zone. This gap is displaced in the direction of movement of the gas group by 0.3 mm from the projection of the axis of the laser beams (the distance between the onset of ionization and the exit of the ions from the ionization region is shifted by this distance). To compensate for the velocity of the ions associated with the velocity of the gas jet, deflecting plates were placed at the output of the ion source, the distance between which was 4 mm. To increase the resolution of the mass spectrometer, an additional electrostatic focusing of ion packets was used according to the mass principle. reflector. For this purpose, an ion reflector was placed in the mass spectrometer, and the trajectory of ion motion in the instrument chamber was chosen as Y-shaped. The ion reflector consists of two electrodes, the creators. reflective field, the depth of coexpensive 12O Mt.i. Two microchannel plates with a diameter of 46 mm were used as the ion receiver. The pipe of the analyzer chamber tube is 750 mm. With these dimensions, the resolution of the mass spectrometer is 6OO with (x; mass peak generation). Its sensitivity is such that when the density of the test gas in a jet is 10 molecules / cm, the ONE ion comes to the ion receiver for each ion ejection cycle. of gas L4 In a jet of 10 molecules / cm, the oscillation of the amplitude of the main mass peaks of the spectrum (due to the statistical dispersion of the number of ions in the packet arriving at the receiver) is 5%. This is sufficient for detecting and investigating most Thus, for example, when high-power infrared laser radiation is applied to sulfur sulfonide (SFf,) molecules scaled in a expanding gas jet, the amplitude variation of the SF and 5F peaks reaches 50%. Thus, after a single laser pulse, with sufficient reliability information about the effect of IR irradiation on 5Fj molecules. When radiation of the laser radiation on the sulfur hexafluoride molecules differing in their isotopic composition, the Vracc spectrometer made it possible to determine the selective change in the mass spectra of the 5 f molecules and their simultaneous excitation. The new BpeMsampolet mass spectrometer also allows measuring the densities of various gas components in a jet, group velocities of molecules in it, taking mass spectra of molecules excited by laser light, observing the deactivation of molecules, and observing cluster peaks at large gas densities in the jet. The present invention makes it possible to study the details of the complex process of the interaction of laser radiation with gas jet molecules, which is important for laser isotope separation. inventions about rmulah Time-passing mass spectrometer containing a pulsed ion source with an electron star and two electrodes limiting the region of ionization, a drift space and an ion receiver, characterized in that in order to extend the functionality, a slit collimator is inserted into the ion source gas jet, two quantum generators and two diaphragm ion sources located on opposite sides for introducing radiation to quantum generators, which are movable, while the collimator Placed in a plane perpendicular to the plane of the electrodes, the ionization region is limited, the median plane of propagation of the gas jet lies between the indicated electrodes, the optical axes of the quantum generators passing through the centers coincide and lie in the median plane of propagation of the gas jet; 1 with an electrode bounding the ionization zone, made with a slit for the passage of the electron beam, and a second electrode with a slit for the passage of ions from the region of the ion beam. a, with the slits in both electrodes parallel to the axis of the laser beams. Inukurk ashgy sources taken into account in the examination of iCossioto hNO, 5chuEi RD, beeX.T., sV) en4.R. AotecutQr eoop Ii) o € lAuElipliodor ttociolioM o S) T6 - .. 1 {eN -e-i ,, 17,19179loossie10

2. Ionov N. P., Mamyrin B. A.3. USSR author's certificate

Maso-spectrometer with an optical source No. 198О34, НО1 J 49 / 4О, 09.06.67. Nikochionov. ZhTF 23, No. 11, 2101, 1953. (prototype).

Phi1.1

Claims (1)

Claim A time-consuming mass spectrometer containing a pulsed ion source with an electron gun and two electrodes that limit the ionization region, a drift space and an ion receiver, characterized in that, in order to expand the functionality, a slotted gas jet collimator, two quantum generators and two located on different sides of the diaphragm ion source for inputting radiation from quantum generators, made with the possibility of movement, while the collimator is located in the plane of the dicular plane of the electrodes that limit the ionization region, the average plane of propagation of the gas jet lies between these electrodes, the optical axes of the quantum generators passing through the centers of the diaphragms coincide and lie in the middle plane of the gas jet, the electron gun is located behind the first electrode, limiting the ionization region, made with a gap for the passage of the electron beam, and the second electrode is made with a gap for passing ions from the ionization region, with gaps in both ektrodah parallel to the axis of the laser beams.