SU1691906A1 - Method of determination of elementary and isotopic composition of substances - Google Patents

Abstract

The invention relates to mass spectrometric survey methods and can be used to measure the composition of rare components in geological rocks, meteorites, semiconductor materials, as well as in industrial waste. The purpose of the invention is to increase the sensitivity due to the space + m-separate time focusing of ions along the three components of the velocity. The essence of the method of determining the elemental and isotopic composition of substances, including the formation of ions, the formation of a bunch of accelerated ions by an accelerating electric field, a vector of intensity parallel to the axis of the ion source — the ion receiver, the impact on the ions by a reflecting electric field opposite to them drift, and the determination of the desired composition after the reverse drift of the ions is that a constant uniform magnetic field is applied to the region of motion of the ions th field, whose field strength vector parallel lines Silovym accelerant and reflecting electric fields, and the value of magnetic field strength set in accordance with the relationship given in the description of the invention. 1il (L S

Description

The invention relates to mass spectrometric survey methods and can be used to measure the composition of rare components in geological rocks, meteorites, semiconductor materials, as well as in industrial waste.

The aim of the invention is to increase the sensitivity.

The drawing shows a schematic representation of a mass spectrometer for implementing the method.

The mass spectrometer includes an ionizing radiation source 1, test sample 2, an ion cluster 3 formation and acceleration system, an ion drift chamber 4, to which a constant uniform magnetic field is applied, a reflector 5, an ion receiver 6,

The method for determining the elemental and isotopic composition is implemented as follows. The sample under study (rock, semiconductor material, meteorite in the form of dust, crumbs, or a whole piece) 2 is exposed to evaporating and ionizing radiation from a radiation source (for example, an IFL-6 LTP laser and a focal lens) 1. The resulting ions have components speeds both along the receiver axis and in perpendio che

u o o o

in the cool direction. Next, the ions are acted upon by an accelerating electric field, the intensity of which is parallel to the axis of the ion source — the ion receiver. In this case, the energy of charged particles is increased by 1000 eV. Simultaneously with the action of an electric field, ions begin to be affected by a magnetic field, the intensity vector of which is parallel to the axis of the ion source — the ion receiver. The impact on the ions by the magnetic field continues throughout their drift to the reflection area. The distance between the acceleration and reflection areas is 450 mm. Structurally, the reflection region is made in such a way that, on the side of the particle drift, an electric field deceleration gap is formed, consisting of two spikes at a distance of 5 mm. On the first grid, the poyumatsial is equal to (the drift gap potential. On the second, 700 V. At a distance of 33 mm from the second grid, the plate is at a potential of And 160 V relative to the drift gap. The selection of the specified dimensions and values of the potentials upon reflection ensures that the ions with an initial energy spread of 20 s 160 eV After reflection on the ions, a magnetic field is applied on the projection of the drift to the receiver. The distance between the drift regions and the receiver is 550 mm. The core uses a chevron microchannel plate assembly.

When analyzing the variations of deuterium in bottom sediments, samples of bottom sediment are used as the test sample. The magnitude of the magnetic field strength is required according to the proposed by the authors) and according to the claims. In this case, L - 2, Q - 1, and T was determined by the well-known formula and was 5.74. As a result, AND 228 O. The deuterium content in the sample is determined by the magnitude of the amplitude of the sapei-grown signal.

The ratio given in the claims is explained as follows.

Let at the moment of time t 0 the discharge of charged particles from the source occurs. All particles have velocity components that are directed both along, Vn, and across the Vj magnetic field.

Due to the transverse component, the oops are moved along the Parmor radii R, and the axes of which are determined from the expression

R (cm) 143.92 tm-L Y7 Cl Ju (E)

0)

0

H (3) Q &. where A is (a.e.m) the ion mass, Q is the ionization rate of ions, e is the electron charge, EL is MVI2 / 2 (eV), Vi is the transverse component of the ion velocity H, the magnetic field intensity (E) .

The period of one complete rotation of the particles is determined from the expression

T Yy- where Vi (cM / c) 1.3585x

hw

one ,

(2)

five

0

five

0

or taking into account the substitution of R from the expression (1)

Tj. (CH, 5288

A / Q

 ten

-four

, Daewoo 1i (3)

From expression (3) it follows that particles with the same magnitude A / Q, which started on an axis that runs parallel to the power lines of the Max field, regardless of their initial energy and direction of motion, return to it simultaneously at time t TI, t The effect of space-time focusing on two velocity components (in a plane perpendicular to the magnetic field lines) is observed, while ions of other masses are at this moment remote from the axis and distributed in space depending on the velocity components.

At the same time, the particles move along the field lines of the Militar field due to the velocity component V11

5 When certain ratios are fulfilled, the mass reflectron provides for an easy-time focusing of ions along the floor. In this case, the focusing of ions, then Vn occurs at the time t T11

To ensure simultaneous space-time focusing on the three components of the ion velocity, it is necessary to fulfill the condition, T T

5 and, therefore, taking into account the expression (31 we will have that

H (e) 6.5288.

Moreover, a positive effect is achieved when using magnetic creeps whose strength is a multiple of the value given in this ratio Increasing the sensitivity of the method compared to the prototype is explained by the fact that eliminating the fundamental restrictions on the sensitivity values of determining low prevalence components against the background of high prevalence the way

0

0

five

The proposed method, in comparison with the prototype, provides an increase in the sensitivity of more than 100 times, which allows the selection of ions that are slightly different in mass, but significantly different in prevalence. Such a possibility is explained by conducting the space-time focusing of ions over the three velocity components. The method allows for the rapid analysis of practically any samples with low quantitative losses.

Despite the fact that an example of a possible specific implementation is given only for deuterium, the generality of properties — the presence of space-time focusing of ions across the three components of the velocity — suggests that the proposed method is applicable to a wide range of low-prevalence components.

Claims (1)

Invention Formula The method of determining the elemental and isotopic composition of substances, including the formation of ions, the formation of a bunch of accelerated ions by an accelerating electric field, the intensity vector of which the ion source is parallel to the axis — the ion receiver, the impact on the ions by a reflecting electric field opposite in direction to the accelerating electric field after their drift, and the determination of the desired composition after the reverse drift of ions, characterized in that in order to increase the sensitivity by spatially - a specific temporal focusing along the three velocity components; a constant uniform magnetic field is applied to the ion motion region, the intensity vector of which is parallel to the accelerating and reflecting electric fields, and the magnitude of the magnetic field H is given from , 5288-10 4Q Y; No. where A is the atomic number of the ion; Q is the ionization ratio of the ion; T is the time of flight of ions from the source to the region of the space-time form VZ energy slices хz -х- along the fields, parallel to Z (с).