DE1948757A1 - Method and device for chemical analysis by electron spectroscopy - Google Patents

Description

Patent Attorneys 1948757 DR. CLAUS REINLÄNDER DIPL-INGKUUSBERNHARDT

D-β MONK 60 . VI P 230 D.

BACKERSTRASSE 9

VARIAN ASSOCIATES

Palo Alto / California / USA

Method and device for chemical analysis by electron spectroscopy

Priority: Sep 30, 1968 - USA - # 763 691

summary

An electron spectrometer is described with which the binding energies of electrons surrounding the atoms of a given sample can be determined. It will be a new type of irradiation device, a new type of ring slot and an electron analyzer having a novel arrangement in which it is possible to detect the Swirling through the electron spectrum without changing the parameters of the analyzer, and with it furthermore it is possible to use unusually large slot widths in order to achieve an extremely high instrument sensitivity to reach.

2 · ■ -. '■; ■' ■ .. ■: ■: ■ -

State of the art

When used generally as electron spectroscopy for chemical Analysis (ESCA) called analysis technique, a certain sample is bombarded with a radiation source, for example

wise a source of x-rays, ultraviolet light, or high-energy electrons, making an electron that initially has a kinetic energy equal to the energy of the beam photon from which the sample is emitted. If any Electron is emitted from the sample, it suffers an energy loss, which results from the binding energy, which is determined by the constitution of the atom. if this energy is measured, it is possible to determine the type in which the various atoms of the sample are bound are · The elemental composition and the valence state of the atoms of the sample can be determined by measuring the binding energy of the emitted electrons can be predicted

Using this procedure, a chemist can determine the valence states Determine certain atoms within a sample by irradiating the unknown sample with, for example, X-rays and then determining the energy of the photo-electrons produced is measured so as to obtain a series of discrete photovoltaic electron energy spectra, each of which represents a different valence state of a particular atom · The change in electron energy due to a change the valence is called the former shift »

In the last few «driving attempts have been made to use electron spectrometers high resolution develop for this type of chemical analysis, for example, the Siegbahn group in Uppsala has developed a spectrometer that has a sufficiently high resolution to allow an energy analysis

0098107134 *

ait sufficient accuracy «u obtained with which this chemical shifts can be determined. This However, the spectrometer was and was a very large instrument not very good for use as a manufacturable analysis suitable for instruments · The spectrometer was more reminiscent of high-energy physics techniques than practical analysis «* tools for use in chemical laboratories

The ESCA method differs from high-energy physics in that the electron energies are generally considerably lower, on the order of 1000 volts, for example, and that the electrons are sent directly into the spectrometer without their energy being changed in any way. When using the ESCA method, it is desirable that it be possible to measure chemical shifts on the order of 1 volt. 1 volt of 1000 volts su measure is required as a minimum resolution of 1 t 1000 · Sas fundamental problem is therefore to obtain such a high resolution, while a highly sensitive analyzer is provided d _e h. an analyzer that has a very high current transmission and a reasonably high mean solid angle.

In practice, the electrons emitted by the sample are not given in large numbers, as is commonly believed. Since the'electron intensity is basically quite is low and the detected electrons are counted individually, the known very large device represents a noticeable help, because it can be seen from the theory that the Sensitivity follows the square of the radius of curvature of the focusing medium, so if the radius of curvature of the analyzer * is doubled, the sensitivity is quadrupled.In addition, the slot width theory shows that zttf \ Brzie-

... / 4 00 9819/13 A 6 = ^ *

With a resolution of 1 t 1000 the slot width must be close to 1/1000 tone of the radius of curvature. So if a small radius of curvature is used, a slide width must also be used which is practically against Hull.

Because all of these factors build a pretty big one Advocate instrument that has very precise dimensions, such a solution technique has been pursued so far.

Summary of the invention

The basic object of the invention, however, is to provide a novel method and an apparatus in which the size of the instrument can be significantly reduced to make it a practical analysis tool, that of a greater number of chemical laboratories and others interested in using the ESCA procedure Can be made available

The invention thus relates generally to electron spectrometers and, more particularly, to a novel spherical electrostatic analyzer and associated devices for use in electron spectroscopy for chemical analysis.

The electron flow allowed through by an ESCA spectrometer is determined by the brightness B of the electron illumination of the entrance slit, where B is measured in units of ^ lektronenstrem per unit area per solid angle unit multiplied by the light intensity Ao) of the spectrometer, where A is the area of the entrance slit and ω is the solid angle aperture of the spectrometer, seen from the entrance slit, is. In ESCA spectrometers, the entrance slit is held the surface of the radiation source in the detector slot

0 098 1 9 / 13A6 \ "^{# /}

forms. The transmitted stream of mono-energetic Electrons of the correct energy for transmission result from the equation:

(D ¹

The brightness B is determined by the strength of the incident Radiation of the sample set. Since the brightness is low, it has heretofore been necessary to design spectrometers with exceptionally high luminous intensity AoJ · These known ones Spectrometers have achieved a second order focus at an emission angle from the entrance slit. As with the The subject of the invention can be the light intensity of the ESCA-

Spectrometer as a function of the following equation

Δ S

the radius of curvature and the fractional resolution

(2) AOJ = CE ²

be expressed wherein mean;

R is the radius of curvature of the centreline · de · rays

Ε the line width in electron-volts »E the energy of the electrons within the Analyzer.

It can be seen that R () is proportional to the slot width ·.

The length of the slit, together with the first-order focusing angle β , gives rise to second-order aberrations which are generally set generally equal to the width of the entrance slit. This results in a further factor H (^ g in the light intensity calculation.

009819/1340

■ -fcärkt is thus proportional to the * square d «a Krüanunge- : radius and the square of the percentage resolution · The : Value of the constant depends on the al! Remote spectroeter type and the choice of the focusing angle oC «further order.

While in known instruments B in equation (2) is the energy of the photo-electrons that are emitted by the sample and is typically in the order of 1000 eV, and the spectrometer is designed so that it has a resolution ΔΕ = 1 eV or reached smaller, in order to observe chemical shifts in the electron spectrum, W is reduced in the spectrometer E according to the invention by placing a variable delay field between the sample and the entrance slit

For example, if E is reduced from 1000 eV to 100 eV the light intensity of the instrument can be increased by a factor of 100 by increasing the slot width and the Recording angle is increased while Δ Ε is held becomes · Furthermore, the larger value of * Hr- makes the dimensional precision of the instrument less critical. Of the

However, the gain in the transmitted current is not equal to 100, because the laws of electron optics force a reduction in the k brightness due to the retardation of the source electrons.

The brightness of the electron beam is proportional to its kinetic energy and is therefore reduced by a delay ί field. If Bq is the electron brightness of the sample, where photo-electrons have the energy E ₀ and E is the kinetic energy of the electron when it passes through the entrance slit, the brightness at the entrance slit can be expressed as:

(3) BV / ^B ° \ E

009819/1346

A reduction in the slectron energy τοη 1000 eV on 100 «V» lee results in a loss factor of 10 for the Brightness * When equation (3) and equation (2) are substituted into equation (1), the thermosetting current can can generally be indicated by the following equation:

(4) ²ⁱ ^ *

frotz the loss of brightness by delaying the Biektronen gives the general opening of the spectrometer Schlitsbreit · and Shot a Nice Profit of the transmitted stream to a Fakter of 10, because that is more than compensated ^ü elligkeitsverlust * nozzle observation has been made aioht.

Because the energy pricing of the source electron spectrum is not changed if all the electrons are around the same Potential difference are delayed »retains the resolution ΔΕ of the spectrometer has a constant relation to the energy » diffirens «wieeheη neighboring peaks in the electron spectrum. In addition, equation (4) does not tend to Grense for the higher transsession caused by the delay of electrons can be reached at the source "The Grense is given by practical requirements, including the difficulty of focusing very slow electrons and of constructing spectrometers with very large apertures"

It should be mentioned that Helligkelt's law \ in equation (3) is independent of the shape of the electrode system, with which the delay is brought about If a sample of small area is used, it may be necessary to Use electrodes that are connected to the source in the input switch of the spectrometer. In the current ESGA process

00 98 1 9/134 6

however, a large area of radiation will naturally be obtained from the X-ray tube or other source, and it is advisable to use a sample of large surface area in conjunction with a simple retardation field "

The device according to the invention operates according to these principles and uses a retatione-symmetrical, spherical one electrostatic analyzer along with exhibited other features * that have not previously been used · While so far all rotationally symmetrical electrostatic analyzers have worked with point sources that have small diameters and lie in the instrument axis, and which with the analyzer onto a small opening at the opposite end of the spectrometer, the Invention instead of a point source with a slot in the form of a hinges. In a preferred embodiment a cylindrical sample is installed in the ring slot and the sample is irradiated with a ring source so that the electrons emitted by the sample through the ring slot step back. The electrons are then selected in terms of energy with a spherical condenser and then on one Similar annular exit slot shown, after which they pass through another focusing condenser, the directs it into the opening of an electron multiplier, and a count of the particles is then recorded

The invention is therefore intended to provide a new type of electron spectrometer small size and very high sensitivity available be made so that the chemist can use the binding energies precisely measure the electrons that surround the atoms of a particular sample material.

Further objects and advantages of the invention will become apparent from the following description in conjunction with the drawing; show it

00.98 19 / 1346-

* YY 0- * fr. «

^ κ »fc _ # e. β- * ► * ■

• 9 * .- ■

Hg »! See the fofcuesier principle used according to the invention

· 2 an Aberratiöns-BiagraiBBi. to illustrate the / mode of operation of the invention!

FIG. 5 is a diagram of an ESOA spectrometer according to the

Fig.4- a Soiiema of another C ^ tielle »who in an inventive appropriate system can be used. * and

Fig. 5 a Scheiaa of another AtisleitrngsforiQ a Köntgen tube waä lhe & b & _t that can be inserted into the system *

In Fig! a cross section is shown "the ä ± e axis of a rotationally synfmetriscben spkäriscken £ öndenso2fß contains the way of illustration of the Fokiissierprinsips the invention Terwendet * is Bie axial focal points are located at positions 10 and 12 _t, and two Kingsefelitsse 14 and 16 are in the Focal planes 1 and 2 are arranged so that the slits lie on the cone of the central rays that enter and leave the condenser. Between the focal points 10 and 12 there is a spherical sensor unit 18 consisting of two electrostatic plates 20 and 22 consists »which form a spherical F / ecussier- * device with which the in the slot 14 i & focal plane Hummer. 1 entering electrons are focused in the bingsole in focusing plane Kummer 2

If a point is 24 on the. Entrance slit 14 is viewed and the line 26 is drawn through the center of curvature of the analyzer 18 »the extension of this line 26 intersects the point 28 on the central ·» ray 1mhDL _f and that is the first order image point. We mean the point

·· I

./ 10 009810/1340

■ 1348757

the EiHgangasehlits 14 is moved feertan * follows obviously ämr Itmkt; 2S generally in the same way © a circle in the focal plane Mizmmer 2 " all coincides with the Einingsehlitz 16". WAM ia exerts distance between the point 24 waae the EriisaataigsiEittelptmkt 0 of the Analyaators nkt shorter than the distance between Ft £ 28 waae the KxümsstwagB- BiittelpiHikt ö _f the BiläsehOLita 16 is in the focal plane HTM Aier 2 slightly larger than the Qitellensefilltz. Could. 14 in the focal plane Hummer t * It is erwähnön _f tHe the Sisgsehlitze 14 tmd brought in. Planes that intersect the axial focal points to bind the 12th " and in this case a Tergröierting 1 would result. " With such an arrangement, however, the slot position would be offset against the beam centerline: wt & therefore-additional undesired aberrations

You Eaergy-Axiflösimg (full width at MaLfeer height) will obtained through the following Sleichiaig

Ce) am - - "';' 3a, ■;"'-. · ■ /

the Ins tr lurtenten-KonstriiiEtioii is optimal, so that the of all i.tterratiöne & equal ,, afcer is not greater than the slit width a «B is the Haiiii® of the ZentraletraKLs inside the spherical condenser. Ba the resolution does not directly contain a Kaiius r des Biagsehlitses 14, can be realized a large »Schlitffifflächs, whereby the sensitivity of the spectrometer is improved «.

Ufer Badiii * E-ies Qnelleneehlitzes 14 finally becomes aberratioßsii »¥ # it # r order b« gres st _? iie proportional to the

Squares of the angles ot, / 3 ι γ , which are shown in Fig.2. The angle oL is formed by the entrance aperture of the capacitor 18 according to FIG. 1. The angles β, T «x are given by the paths, for example AC, which do not lie in an axial plane. From the source point A part of the central path is given by the line AB. This lies in a plane which is formed by ABO and which contains the axis FO of the analyzer, where 0 is the center of curvature of the spherical condenser. Considering a non-central trajectory, e.g. AC, which enters the condenser aperture at point C and lies on arc BC defined by angle G as shown, the trajectory passing through AC must be entirely in the plane defined by ACO because the spherical condenser supplies a spherical electric field. This plane lies at an angle β with respect to the axis of the instrument and ensures that the particle runs a longer path within the condenser. In addition, the central or normal ray passes through C through point D on the ring shell, and it can be seen that source point A is decreased relative to point C by a distance DE. This results in a further aberration which is defined by the angle χ .

The properties of the spherical field require that all Paths from point A define planes containing point 0, the center of curvature. The Purcell condition shows then that all of these rays have a common focus first Have order on the exit slot. It can then

will show that second order aberrations are dislocations Cr against the focal point of the first order, the size of which is given by

(7) cfr * 2R-X. ² + 2Rr ² + H ß

... / 12 00 9819 / 13Λ 6

·· · · t ♦ t ♦
► * t 4 * tf

■ - 12 -

If the slit width is a, then the optimal design calculations indicate that the sum of these aberrations should be equal to a, and that it should be set separately

(8) 2R06 ² m - ^ -

Since γ and ρ are clearly related to the azimuthal angle Φ, the second condition results in a limitation of the angle β to a value smaller than it is given by .

(! Ο) G-

For given aberrations, it is evident that the product Tin 9 and the radius r of the ring connector 14 are a constant is. In Figure 2 the arc length AB is on the source slot equals βτ, and that therefore gives the maximum slot length, from which a given point B on the condenser aperture can be irradiated. It follows that the sensitivity of the spectrometer roughly speaking regardless of the radius The input slot8 is, as long as it exceeds the value, for the β ä *. 3Γ is. However, it was found that for angle 0 greater than or equal to - ^ - the line shape of the spectrometer forms long wings, and it is therefore desirable to limit 0 to values less than —s—.

... / 13 0 0 9 8 1 9/1 3 Λ 6

• · ti

- 13 -

In the above analysis, the approximation is also assumed that r is considerably smaller than R, and the maximum permissible value ν · η r is therefore determined by this consideration limited. Within these limits, the value of r can be limited by other factors, such as the sample, size, etc.

The azimuthal beam divergence angle 0 as shown in FIG. 2 is controlled by an opening 29 located at the intersection point 12. If the angle Q is the chosen azimuthal recording angle, then the radius d of the intersection opening is given by the equation

(11) 2 sin-f- = -f-

where r is the radius of the slot 24

It was also found that the sensitivity of the Spectrometer according to equation (4) can be increased if the energies of the photo-electrons are reduced before they are on the input base of the spectrometer stand out. If the electron intensity is also reduced, it is found that, if E is reduced, the apertures of the spectrometers change with open at a rate greater than the loss of source intensity so that the net current transmission is enlarged. If E is the initial photo-electron energy and E is the energy entering the analyzer, it is determined that the current I transmitted by the spectrometer obeys the following relationship

009819/1340

194I7S7

■ '- 14 -

In practice, the electron energy is usually _{reduced to a value E * 100 eV from I 0} ~ 1000 ·, so that the current passed through is increased by a factor of 10. Instead, the radius of curvature E of the analyzer can be reduced for practical reasons.

In Pig * 3 is a preferred embodiment of the invention As can be seen, a shaft 32 extends through a vacuum chamber wall 30 and at one end carries a sample cylinder 34 onto which a sample to be analyzed can be deposited. The sample cylinder 34 can be any have a suitable length and is obtained by moving the shaft 32 axially displaceable. An annular X-ray anode 36 is arranged around the axis of the shaft 32, through which means a coolant is sent to the through-duct 38. The cylinder anode 36 is typically made of stainless steel Steel and has a vapor-deposited aluminum layer on the Surface, or a layer of another metal, its Characteristic X-ray radiation is desired

Since the type of X-rays delivered by the anode 36 depends on the type of anode material, aluminum has been chosen because it has a very narrow line shape and delivers low energy photons. Low energy photons cause electrons with low energy emanate from the sample, which are easier to analyze with the required degree of precision · Even if aluminum is not the best interceptor material available is as both magnesium and sodium are more beneficial from an energy and standpoint However, it was found that Altuninium ι is a practical material for this application «

In order to generate the high-energy electrons for impact on the X-ray suspension, a ring-shaped X-ray

0098 18/134 6 ⁹ * ^{m / 1}

ORIGINAL INSPECTSD

ι t · w * · fftr

t «· ι

- 15 -

tubular heating wire 40 is provided concentrically to the anode 36. In the same way, however, is a cylindrical shield Torgeeehen, immediately between the wire 40 and the anode 36, bo that the electrons emitted by wire 40 by the. Abeohirmung 42 are deflected so that they hit the surface 44 the anode 36 impinge and x-rays in the direction of the emitting cylindrical sample 34

This construction of the instrument is very sensitive auoh against very small magnetic fields and the one in wire 40 flowing · Current tends to have a magnetic field in the input part of the analyzer, therefore a power supply rail 46 is provided which runs concentrically to the wire 40, to cancel the magnetic effects of the current in wire 40 · The current return bar 46 is electrically in series with the wire 40 and is arranged so that the current flow in the rail 46 is opposite to the current flow in the wire 40 is directed so that its magnetic effect is effectively canceled.

In this embodiment of the invention is the Wire 40 to ground and the collector anode 36 to high positive tension. If such a potential arrangement is chosen, the probability that external Electrons entering the system are significantly reduced. That is an essential feature of the invention because the counting range of the device can go down to 10 electrons per second at the detector It is easy to see that any outside electrons going into the analyzer would significantly affect any readings received. .

In order to obtain a filter for the X-rays impinging on the sample 34, a very thin aluminum foil 47 is used

... / 16 009819/1346

■ - ■■■■■■ - 16.— ■. "■. ■" ■■. ■■■ - ■ '■■. ■■■' ■■■ '.

on the order of a few thousandths of a millimeter (some Tenths of a mil) positioned between the anode 36 and the sample 34 across the x-ray path. The purpose of this filter consists in blocking low-energy X-rays generated by the aluminum anode

^T he sample 34 is disposed within the circular opening in the plate 46, which together with an arranged around the axis of the sample around tube 50 into which the sample can be projected, is an input slit 52 through which the light emitted from the sample Poto "electrons in the spherical w condenser 54 to enter the condenser 54 consists of two truncated cone-shaped concentric spherical plates 56 and 58 which form a spherical focusing means to focus the exiting from the slot 52 electrons so that they by a subsequent focus eggs opening 60 pass through the plate 62 which is mounted on the tube 50 and serves as an entrance opening for the electrostatic focusing device 54. A similar opening 64 is provided in a plate 66 at the exit end of the spherical focusing device 54. A positive voltage is applied to the inner electrode 56 of the electrostatic focusing device 54 and a negative voltage is applied to the outer electrode 58

If the slot 52 is considered again, it is from the drawing it can be seen that the plate 48 and the tube 50 are at ground potential and that a variable voltage source 70 is provided with which the potential applied to the sample 34 can be swept · This creates a variable delay field is generated between the sample electrode 34 and the slot 52, thereby making it possible to reduce the energy of the electrons that enter the analyzer, thereby sweeping the energy spectrum of the electrons emitted by the sample · If it is also possible, the range of

• ../ ■ 17

9819/1346

swirling emitted electrons through other methods the use of the delay field has considerable operational advantages because it is not necessary to use the potential to change which is attached to the spherical focusing electrodes of the Analyzer 54 You can use the wobble function as in this apparatus can be performed without changing any of the operating parameters of the actual analyzer got to.

At the output end of the spherical analyzer 54, a set of focusing electrodes 54 is provided, which consists of an inner plate and a segmented outer plate 76. The focusing means is erforderlioh to ensure that the resulting image is a perfect circle when it is displayed in the 'focal plane. 2 Whilst this is ideally achieved by the spherical plates 56 and 58, in practice this is not done by the sensitivity of the device to disturbances from small imperfections in the dimensions and from residual magnetic fields of various kinds which cooperate in such a way as to offset the image somewhat and is distorted. These electrodes 74 and 76 are in a certain sense an extension of the condenser itself, only that the electrode 76 is segmented, preferably into at least eight equal segments, and the potential that is applied to these eight segments by a voltage source 77 is variable, so that the circuit can be changed so that the exiting electrons form a perfect circle. This is of course done to allow adjustment of the position and shape of the final image

As already discussed in connection with Fig. 2, there are certain sample electrons that go into the focusing device 54 enter at an angle to the plane that the Includes axis of the device. These electrons have large aberrations

0098 19/134 6

1 * 4.8787- ■■■

- 18 -

functions, and to obtain a high device-related resolution) it is desirable that only the electrons are transmitted to the second focal plane which are within a given Aberration range. To such troublesome electrons To eliminate, an apertured plate 78 is inserted in the path of the electrons coming from the focusing condenser 54 go out. The plate 78 is located at the intersection of the electrons closest to the center, exiting from focusing condenser 54 · The ring opening has a diameter large enough to contain only the aberration electrons which enter the analyzer at angles smaller than a specified deviation. Of the Deviation angle Θ, which has been mentioned in connection with Fig.2 so is completely controlled by the size of the opening, and if an appropriate diameter for this opening is selected, the permissible angle θ is specified.

Another aberration path is controlled through the opening 60, namely that indicated in FIG. 2 by the angle oL. This is an angle in a radial plane and the maximum allowable angle oL is selected by the size of the opening 60.

After the electrons exiting the focusing medium 54 pass through the intersection at opening 80, they follow a conically diverging path to a second focal plane where a second hanging slot 82 is provided to receive the desired electrons. The slot 82 is formed by a plate 84 having a circular opening and the cylindrical electrode 86, 1st arranged in ι the opening of the plate 84 the end thereof. As can be seen from the drawing, both the plate 84 and the cylinder electrode 86 are at ground potential.

... / 19 0098 19/1346

ORONAL INSPECTED

et »ir
• ι * * »· ·

l * tr

- 19 -

After the electrons pass through the slit Θ6, they enter another focusing condenser 88 which has cylindrical electrodes 86 and 90 which, when biased as shown, create an electrostatic field between them, with which external electrons are eliminated and which ensures that the accepted electrons are focused on the entrance opening of an electron multiplier, 92. Each electron entering the electron multiplier 92 provides an output pulse which is amplified in a pulse amplifier 94 and then counted in a counter 96; then he is in a ^multiscale: computer 98, for example, CAT-400 recorded. The negative voltage on electrode 90 is also an important means of preventing external, low-energy electrons from entering the electron multiplier _;

The wobble of the computer 98 is synchronized with the wobble generator 70, which supplies the wobble voltage, the sample 34 places · With each sweep, the computer 98 j performs a multi-channel addition and storage operation, the t when reproducing on an oscilloscope or recording) meohaniemus a graphic display of the energy spectrum of the Delivers sample that has been scanned by the spectrometer.

As is usual with this type of device, the spectrometer must be operated under high vacuum. A vacuum holding device 100 is therefore provided in the manner shown, which extends into the vacuum chamber wall 30 of the spectrometer.Since, as already mentioned, the spectrometer is extremely sensitive to the smallest magnetic disturbances, for example in the milligause range, it is necessary that ■ the pump 100 does not generate Hagnetfelder, which could introduce a Hagnetfeld in \ dae spectrometer.

A! Itan sublimation pump of the type shown in the drawing

009819/1346 ... / 20

1948717

- 20 -

Kind, has been found useful for this application been. This pump consists of two rods 102, one Titan chunks "104 carry" to the from an external source a high voltage is applied. A heating wire 106 is provided in the same way to ensure a constant flow of electrons to deliver, which bombs the titanium chunk 104, so that it sublimates and becomes with the gases in the system mixes so that it chemically combines with these gases, so that the strongly'bound mixture on the water-cooled Surface 108 of the pump 100 is plated.

In Fig. 4 is another embodiment of a sample carrier shown with an X-ray source, which can be used instead of the sample irradiation mechanism according to FIG. At this Another embodiment is provided with a conical anode 110, which is bombarded with an electron beam from a wire, so that X-rays are generated, that hit a sample material that is on the inside a generally annular sample support structure is applied in the form of a truncated cone. When the photo electrons are emitted from the sample, they can pass through an annular slot 116, as in FIG described structure, only that it is the axis of this structure cross, before entering the spherical analysis capacitor 54 ·

Another embodiment of a sample support and irradiation arrangement is shown in Fig.5. The sample material lies as a layer on the surface 118 of a sample plate 120, which is disposed within a sample cavity 122 and lies in a plane perpendicular to the instrument axis ·. As In the embodiment according to Fig. 3, the sample 118 is with an X-ray beam enque He irradiated, which consists of a ring anode 124, a filament 126 and a rail 128,

... / 21 0098 19/1346

OROfMAL IMSPECTgD

i · i

t · »k ι i

- 21 -

and which has a thin aluminum foil 130 attached thereto serves to block very low-energy X-rays generated by the anode 124.

An inlet opening 132 which is in a focal plane of the energy analyzer of the system, for example the electrostatic analyzer according to Pig · 3 »is through a with a opening-provided element 134 and the end of the cylindrical Element 136 is formed. When the photo electrons from the Sample 118 emitted due to bombardment from the annular x-ray source 124, they pass through the Slit 132 through it and into the analyzer which is performing an energy selection puncture and the electrons focused on a detector with selected energy, as illustrated in Pig. 3.

The operating mode of the device should still be in connection with Pig, 3 to be discribed. First, the cylindrical sample holder 34 can be coated with as many different types of sample material as are to be analyzed. These sample layers are deposited on the surface of the sample holder by forming rings which are selectively with the x-rays from the anode 44 can be "bombarded" by simply moving the sample holder 34 along its axis will. When the sample is bombarded with the X-rays, photo-electrons are emitted and pass through the slit 52 into the cylindrical analyzer 54, which in turn ensures that they are focused on a second plane.

The energy spectrum of the sample material is swept by that a variable voltage is applied to the sample 34 while the surfaces 48 and 50, which define the slot 52, on Ground potential are maintained. A desired energy level of the sample electrons can therefore be chosen that is to the spherical

/ 22

009819/1346 ■

--22- _^v:; ;. . . ■■ '■. r.- ■■■;

see focusing device 54 is let in. In general Practice becomes the potential of

a wobble generator 70 which can be caused within any given sweep voltage range f to switch.

When the electrons emerge from the focusing device 54, the potentials applied to the segments 76 of the secondary focusing device 72 are adjusted so that the electron image is aligned with the image aperture 82 in the focal plane 2.

As previously described, aberrated electrons entering spherical analyzer 54 at angles outside the selected range are rejected by plates 60 and 78. The remaining focused electrons pass through the ring opening 82 and into the cylindrical condenser 88, where they are focused on the entrance of an electron multiplier 92. When an electron enters the multiplier 92, an output pulse is generated which is amplified by the pulse amplifier 94 and counted by the counter 96. The counted result is then fed to a multi-channel computer which stores the input data and provides a power spectrum representing the examined w sample material.

While the analyzer and electron focusing device described is built up electrostatically, it must be taken into account that a magnetic equivalent is used both instead of the spherical analyzer or the analyzer exit correction device, or can be used both as an analyzer and as an exit correction device. Also the The sample and irradiation device can be designed differently be to the device's various uses to adapt

ί · ■ ·· / Claims

0098 19/1346

Claims (1)

V1 P 230 D Claims Method for electron spectroscopy in which a sample material is irradiated so that it emits charged particles and the charged particles through a slit in the vicinity of the sample material can be passed to an analyzer which carries out an energy selection and focuses the selected particles on a detector, characterized in that a potential is placed between the sample material and the slot which is sufficient » reduce the energies of the particles that pass through the slot, considerably, so that unusually large Allows seat widths and opening angles for particle pick-up will. 2 · Electron spectrometer, consisting of a device for irradiating a sample material, a slot arranged in the vicinity of the sample material so that the particles can pass through it, a detector for charged particles and an energy analyzer located between the slot and the detector is arranged, characterized in that the slot is annular and lies in a focal plane of the analyzer, so that the analyzer ensures that charged particles of selected energies are focused in the detector. 3 · Spectrometer according to claim 2, characterized in that ' a device is provided with which a variable potential is placed between the sample material and the slot so that a variable delay field is generated, ... / 24 009819/1346 with which the energy of the charged particles is selectively changed, passing through the slot and into the energy analyzer step" 4. Spectrometer according to claim 2 or 3 »characterized in that that the sample material is arranged on a generally cylindrical sample electrode which is coaxial with the Ring slot is arranged. 5 # spectrometer according to claim 4 »characterized in that tk an annular radiation source is provided coaxially to the sample electrode, so that a peripheral surface of the sample electrode can be irradiated. 6. Spectrometer according to one of claims 2 to 5 »thereby characterized in that the energy analyzer has a spherical electrostatic EJKonäensor, which has an energy selection and focussing function, so that the energy spectrum of the charged particles emitted by the sample material be emitted, can be examined. 7. Spectrometer according to one of claims 2 to 6, characterized in that that the detector has a second ring slot ρ, which lies in a second focal plane of the spherical analyzer, and an electrostatic condenser, with which the charged particles, which pass through the second ring slot, on a detector for charged Particles are focused. 8 · Spectrometer according to claim 7, characterized in that the electrostatic condenser is cylindrical. 9. Spectrometer according to claim T _9, characterized in that the electrostatic condenser is spherical. ... / 25 0 0 98 19/1 34 6 I · - 25 ~ 10 · Spectrometer according to one of claims 2 to 9 »thereby ge» indicates that the central orbits of the charged. Particles » that run between the slot and the detector have a crossing point on the instrument axis, and that one Aperture is arranged at the crossing point by the angle 1 divergence to limit the charged particles. 11 «Spectrometer according to one of claims 6 to 10, characterized in that that / two concentric frustoconical electrostatic correction electrodes, of which at least one divided into a number of curved segments, arranged at one end of the spherical condenser, so that at the exit end of the analyzer, focusing correction steps can be carried out. 12. Spectrometer according to one of claims 2 to 11, characterized in that that the sample irradiation device consists of an annular X-ray source which is coaxial with the Slit and so arranged relative to the sample that of of the sample emitted charged particles through the ring slot and put into the energy analyzer 13 * spectrometer according to claim 12, characterized in that the sample material forms a flat surface perpendicular to the axis of the slot 14 · Spectrometer according to claim 12, characterized in that the X-ray source has a ring anode and one coaxial therewith having ring-shaped filament, the aü & "a wire-shaped Head and an annular busbar, which is arranged coaxially to the wire-shaped conductor and in its vicinity is, wherein the wire-shaped conductor and the busbar connected in series but arranged so that 009819/1346 * β »1 t * * ο i β lit 19487 §7 ~ 26 - the current in the rail flows in the opposite direction to that in the neighboring wire-shaped conductor »see above that any magnetic field generated by the wire-shaped conductor will be extinguished " 0 0 9819/1346 Blank page