JPS6217647A - System for controlling transfer of specimen holder - Google Patents

Abstract

PURPOSE:To obtain a mass chromatogram in the measurement of TLC/SIMS with high sensitivity and good efficiency, by stopping the transfer of a specimen holder during the scanning of a magnetic field or acceleration voltage and transferring said specimen holder during the return time of scanning. CONSTITUTION:The ion beam from a primary ion source 4 is accelerated to about 8keV to be allowed to irradiate a target 1 and the coating specimen thereof receives sputtering and a part of said specimen is converted to an ion. Ion acceleration voltage of 3kV is applied to a specimen holder 2 and a secondary ion accelerated at 3keV passes through a lens 9 and an object point slit 8 and is separated on the basis of a mass/charge ratio to reach a detector 7 through a collector slit 6. This detection signal is processed by a computer 10 to be recorded by an output apparatus 11. When the holder 2 is moved by a mechanism 3, the specimens A-D developed on the target 1 are successively ionized to be measured and recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a mass spectrometer, and in particular to a sample holder convenient for performing secondary ion mass spectrometry (SIMS) on a sample developed on a thin layer chromatography plate. The present invention relates to a device equipped with the following.

[Background of the invention]

In recent years, TLC analyzes samples developed on thin layer chromatography (TLC) plates using secondary ion mass spectrometry (SIMS).
/SIMS is now available. An example of its outline is given in the above-mentioned document. In order to continuously measure the separated spots on the plate at this time and efficiently collect data using a computer system, it is necessary to transport the sample holder that holds the plate in accordance with the data collection timing of the computer. An invention is what is left over from its embodiment.

[Purpose of the invention]

The purpose of the present invention is to move the sample holder in accordance with the timing of data collection in order to efficiently and sensitively create a mass chromatogram in which the horizontal axis is a value proportional to the transport distance in TLC/SIMS measurements. The purpose is to provide an optimal control method for transport.

[Summary of the invention]

In order to achieve the above objective, we adopted a method in which the transfer of the sample holder is stopped when scanning the magnetic field or accelerating voltage necessary for mass spectrum measurement, and the transfer is performed during the return time of the scan. It was decided that data would be collected during the process to suppress changes due to the transfer of each component.

[Embodiments of the invention]

An embodiment of the present invention will be explained with reference to FIG. In FIG. 1, the ion beam generated by the -order ion source 4 is about 8
It is accelerated to KaV and irradiates the target 1. The sample coated on the target is sputtered, and some of it becomes ions. The sample holder 2 has an ion accelerating voltage 3
Since KV is applied, the energy colliding with the target is 5 KeV, and the energy with which the secondary ions are accelerated is 3 KeV. The secondary ions pass through a lens 9 and an object slit 8, are separated by a magnetic field 5 according to their mass-to-charge ratio, pass through a collector slit 6, and are detected by a detector 7. The detected signals are processed by the computer system 10 and then recorded by the output device 11. in this case,
Usually, by changing the strength of the magnetic field or the secondary ion accelerating voltage, all ions with mass-to-charge ratios within a desired range can be recorded. On the other hand, when the sample holder 2 is moved by the transfer mechanism 3, samples A, B, C, and D spread on the target 1 are ionized one after another and measured and recorded, as shown in FIG. Become.

At this time, if the sample holder is simply transferred continuously at a constant speed, it will take time to measure the sample, and the matrix such as glycerol added to the target will dry out, resulting in a uniform transfer from the beginning to the end of the measurement. There were disadvantages such as not being able to measure data under certain conditions. Therefore, in the present invention, as shown in Fig. 3, the transfer of the sample holder is stopped at the developed sample position (for the time required for sample measurement), and measurement is performed by changing the magnetic field or acceleration. During this period, changes in the magnetic field or accelerating voltage were stopped, and the sample holder was transferred at high speed. From the opposite perspective, this means that during data measurement due to a change in the magnetic field or accelerating voltage, the transfer is stopped, and while data measurement is stopped, the transfer is stopped (necessary due to the return time of the magnetic field or accelerating voltage). By doing so, it also means achieving efficient data measurement. As shown in Figure 3, there are 1 scanning methods for the magnetic field or accelerating voltage while the transfer is stopped.
Examples of possible methods include performing multiple scans at low speed to obtain a mass spectrum with good sensitivity, or performing multiple scans at high speed and obtaining an integrated value to obtain a spectrum with an improved S/N ratio.

Further, as another specific embodiment of the present invention, an example shown in FIG. 4 will be given. In FIG. 4, the sample is moved at a low speed for a predetermined distance 48 centered on the developed sample position, the sample is moved at a high speed between each sample, and cyclic data is collected at a high speed while the sample is being moved at a low speed. and stop data collection during high-speed transport.
This makes it possible to observe changes in chromatography of each sample, as shown in FIG.

The TIC in Figure 5 is an indication of the total ion amount obtained from the mass spectrum obtained through high-speed data collection.
! ! m4 is recorded by focusing on the mass of the unique component of the sample in D.

As described above, according to the present invention, the sample holder can be transferred efficiently and the first-order effect can be obtained.

〔Effect of the invention〕

According to the present invention, (a) TLC/SIMS measurement time can be shortened. (b) The loss of matrix such as glycerol, which makes sample measurement effective, can be minimized, allowing stable measurement over a long period of time.

For example, the development of a normal sample F! @The distance is about 50m,
Among them, some parts of the sample are about 2IIIl.

If samples are transferred continuously, 250 aac is required even at a transfer rate of 5 sec/II, but according to the present invention, four samples can be measured by transferring the samples at a rate of 0.5 sec/1 mm. For example, transfer time between samples (501m-2m x 4 pieces) x 0
．． 5 sec/an = 21 sec sample measurement n
R(2mXJ)
4. %.

Therefore, the reduction in matrix is also proportional, allowing approximately 4 times more stable measurements.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, FIG. 2 is an enlarged view of the sample holder shown in FIG. FIG. 5 is a diagram showing another specific embodiment. DESCRIPTION OF SYMBOLS 1. Target, 2... Sample holder, 3... Transfer mechanism, 4... -order ion source, 5... Magnetic field, 6...
Collector slit, 7...Detector, 8...Object point slit, 9...Lens, 10...Computer system, 11...Output device.

Claims (1)

[Claims] 1. An apparatus that has a sample holder holding an object having a sample spread out at a distance, ionizes the sample, and performs mass spectrometry for secondary ions, wherein the sample holder is As a transfer method, high-speed transfer is performed between the developed sample positions, and transfer is stopped at each sample position or low-speed transfer is performed near each sample position, and secondary ion spectrum data is transferred during high-speed transfer. A sample holder transfer control method characterized in that data measurement is performed once or repeatedly only when measurement is stopped, transfer is stopped, or during low-speed transfer. 2. A sample holder transfer control method as set forth in claim 1, characterized in that the transfer is performed in synchronization only with the period during which data collection is stopped, thereby increasing the efficiency of data collection.