DE1950938C3 - Mass spectrograph - Google Patents

Description

30 shift reached.

But since the chopping voltage has a finite increase

The present invention relates to having mass and decay times during these Zci

speklrograph with a pulsed discharge ion- th the ion beam on a displaced position dei

source and focused with a radiation-sensitive layer from the same clock. this leads to

Selectable phase shift controlled electro- 35 to blur the spectral lines, with which

static ion occlusion with deflection electrodes before the resolution also decreases. But even then

a screen between the ion source and the separation space. when the ion beam in the longitudinal direction of the spec-

When analyzing the elementary composite lines when chopping, this becomes

The calculation of substances in a mass spectrograph becomes spectrum because of the aberrations of the second order:

generally a radiation-sensitive layer 40 blurred when spherical, electric field, 1

is used on which the multiple spectra are used.

holds. Since the intensity of the various spectral lines is very different, the load of the respective exposure also varies. In the case of the mass spectral type described, in which the total amount κ duration of each individual ion current pulse of the ions contained in a spectrum is measured from the entire temporal troscopic analysis. a time interval of adjustable length as well as the degree of blackening of each spectral line is directed onto the photo plate. During the übridem appropriate spectrum. One obtains here about the time of the pulse duration, the ions are deflected from their differences in blackness between the brightest and the path to the photo plate. As a result, one of the darkest spectral lines on the film, the maximum exposure dose of 50 with the quantitative mass, should be a factor of 100 apart. In order to be able to achieve da- spectrometric solid-state analysis, different spectral lines from the same. In contrast, the object of the invention is to be able to compare the degree of blackening, which must be to provide a mass spectrograph in which multiple spectra are measured in such a way that one disturbance of the focusing of the ion beam total exposure of the ion beam over a Bc- 55 is avoided and the resolution of the spectral lines ^{varied from K) - IS} Coulomb to 10- * Coulomb is improved.

will. In order to avoid such a large change in the

To achieve the range, the exposure time graph of the type mentioned must according to the invention

can be varied. To regulate the exposure time proves solved that the ion source during the

However, to be very unfavorable, since the exposure time 60 rise and fall time of the ion shutter

emits no ions over a range of 1.8 x 10- "seconds to open pulses.

30 minutes or even longer times can be varied. With the help of the invention, it is possible to

that would have to. Therefore, with the previous methods, the rise and fall times of the must

the pulse opening the amount of ion shutter generated by the ion source determines the direction of the

Ions regulated. Maintaining focused ion beams for a spark ion source 65

The invention is illustrated by the following examples

generated ions regulated by the fact that the spark and the drawing explained. In this shows

voltage, the fin pulse width or the f i g. 1 a block diagram of a typical double

<e

focusing mass spectrograph according to an embodiment of the present invention with a control system that regulates the proportion of the ion beam used for exposure;

2 shows a diagram of pulse shapes for explanation of the present invention.

In the mass spectrograph according to FIG the sample to be examined on the radio electrodes 1 attached and ionized by a spark generated between these electrodes. The on this Wise formed ions are accelerated between an accelerating diaphragm 2 and by a Erdungsblendt- 3 and a main screen 4 passed into the analyzer tube. With the reference number 5 is the deflection electrode, with 6 the electric field, with 7 the magnetic field and with 8 the photographic plate designated. The spark electrodes 1 are connected to the output terminals of a high frequency generator IO connected via a transformer 9. A clock generator 11 generates periodic pulses with constant Intervals according to Fig.2a, that of a delay circuit 12 (which can be a multivibrator, for example) and a gate circuit 14 will. The clock steps with the constant intervals, soft in the delay circuit 12 as are given there by a fixed amount of time '^ i (for example 5} isec) delayed. They are then sent to a first pulse generator 13 supplied, which generates radio pulses with a pulse width Λ /, (for example 2 () (isec) according to FIG. 2b. These spark mini-pulses are then input to the high-frequency generator 10, which is an intermittent A high-frequency signal is generated which, after amplification by the transmitter 9 «n the spark electrodes I is created. This creates a spark between the spark electrodes. The on Samples attached to the spark electrodes are ionized as a result.

The periodic pulses supplied by the clock generator II to the gate circuit 14 are then input to a frequency divider 15 which is designed such that it generates one pulse for each N pulses of the clock generator. Here, N can be varied within a wide range, up to / u at most K) ¹ . The pulses generated by the frequency divider 15 are then fed to a second pulse generator 16 which generates the pulses according to FIG. 2c. These pulses have a pulse width Λ /., (For example 50 | isec), which is wider than the pulse width Λ r, of the spark pulses. These pulses are now applied to the deflection electrodes 5 so that the intermittent ion beam generated between the spark electrodes 1 can only pass through the deflection electrodes 5 when the aforementioned pulses are applied to the deflection electrodes. This ensures that the intermittent ion beam is introduced into the electrostatic field 6. Each ion reaches the deflection field formed by the deflecting electrode with a time difference corresponding to the difference in mass of the ion, and with a time difference during the passage through the Ablenkä ^r egion.

Now, as the pulse width "/)" of the pulses of the pulse generator 16 is much greater use than the Impulsbreitedi, the pulses of the pulse generator 13, and since diiese pulses of the pulse generator 16 over the radio pulses because of their run dt by the delay circuit by a time earlier, the ions to be analyzed pass between the deflection electrodes without any deflection. This ensures that the focusing of the ion beam is not impaired! will.

In the embodiment described above, it was achieved that in each case a spark pulse on the Pulse of width ti /. That met pulses "applied to the deflection electrodes. This particular choice is not absolutely necessary. It is also possible to combine some of the spark pulses in one pulse interval Λ /., To drop the pulses applied to the deflection electrodes. Of course you can apply the above procedure also to single focusing mass spectrographs.

In accordance with the above statements, the present invention provides a control method to the To regulate proportions of the ion beam for the exposure in such a way that pulses generated by a clock with a certain delay time are applied to the spark electrodes and that pulses with a much larger width than the width of the spark pulses synchronous with the clock steps of the pulse generator 16 to the deflection rods be created. This allows a desired ion beam to pass between the deflection electrodes without the ion beam having to be deflected by an interrupter. In this way a clear image can be sent to a corresponding point of the radiation-sensitive Layer to be focused. By regulating the ratio between the footsteps of the Frequency divider and its exit pulses can determine the intensity of the magnetic field reaching Regulate the ion beam without affecting its focus.

1 sheet of drawings

Claims (3)

t 2 ■. . Sparkelectroderj applied repetition frequency regulated Patent claims: are. In this method, however, the ionization conditions change with the change 1. Mass spectrum graph with a pulsed of the spark voltage, the width of the spark pulse c Discharge ion source and with one of the same 5 or the repetition frequency. This leads to a shower Clock generator with selectable phase shift in the efficiency of the ionization between Exercise-controlled electrostatic ion sealing of the various elements forming the sample, with deflection electrodes in front of an aperture between even if therefore spectra with the same ion source and separating space, thereby clearing and producing the same sample, at that the ion source (1) selects the ratio of the blackenings between rend the rise and. Fall time of the ion of each spectral line due to the change in the ionic shutter opening Pulses no ions: ausation conditions in the source. The reproducer sends The availability of the measurements is therefore limited to 15 to 30 ",, 2. Mass spectrograph according to claim 1, there and also unevenly reduced. characterized in that the deflection 15 To overcome these disadvantages were verelcktroden (5) Various methods of ion occlusion are used, including typical pulses A greater width is basically a regulation of the exposure via a sub-pulse for generating the ion beams. breaking the ion beam. 3. Mass spectrograph according to claim 1 or in this method, the electrodes are in front of the 2, characterized in that a single clock 20 electrostatic field is attached to which the Zcr encoder specifies clock steps, which is used on the one hand chopping voltage. The ion stream passed by de ι a first generator { 10) to generate the ion source to the analyzer, the discharge pulses for the ion source and duich the chopping voltage so unicrbi. on the other hand, a second generator (16) to ensure that the amount of ions arriving at the detector generating the pulses for the deflection electrodes 25 is regulated. Control the ion beam wii.l (5). distracted from his path when the Zci- Hacker voltage is not applied, while it is applied the chopping voltage continues undisturbed runs and in this way the radiation sensitive !.