JPH08327601A - Ionization system for sample - Google Patents

Abstract

PURPOSE: To prevent the effect of hot electrons emitted from a heater. CONSTITUTION: A nozzle 1 having an orifice la of microdiameter projected, at the forward end part thereof, into a vacuum housing 11. An inclining electrode part 4 is disposed in the gas flow jetted from the nozzle 1 and a collector 5 for receiving ions, generate through collision of gaseous molecule, is disposed at the electrode part 4. In order to heat the forward end part 2 of nozzle, an infrared light source 6 and an infrared reflector 7 for condensing the infrared rays from the light source 6 at the forward end part 2 of nozzle are disposed on the rear side of the electrode part 4. The vacuum housing 11 is then evacuated and the electrode part 4 is sustained at a predetermined high temperature. While heating the forward end part 2 of nozzle by condensing the infrared rays from the infrared light source 6 thereat, a sample component is introduced, along with a carrier gas, from the nozzle 1 and ejected through the orifice la into the vacuum housing 11. The sample component collides against the surface of electrode part 4 and ionized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detector for a gas chromatograph, an ion source for a mass spectrometer, and an ionizer for an analyzer that needs to ionize and measure sample components.

[0002]

2. Description of the Related Art A small-diameter orifice at the tip of a nozzle is provided in a vacuum device, and a sample component gas is introduced into the nozzle together with a light carrier gas such as helium and ejected into the vacuum device. At the same velocity as the above, the gas is ejected from the nozzle, and the ejected gas is in a supersonic jet state, and the sample components in the gas, for example, organic substance molecules have high kinetic energy. By colliding the sample component with a metal surface or the like, highly efficient ionization becomes possible. It is also known that such an ionization phenomenon can be used as a detector of a gas chromatograph and an ion source of a mass spectrometer.

When the gas is ejected from the nozzle, the adiabatic expansion of the gas cools the tip of the nozzle,
In the case of an organic substance molecule having a high boiling point, there is a risk of condensation at the tip of the nozzle. To avoid such inconvenience,
It is conceivable to wind a metal resistance wire such as tungsten, rhenium, or platinum on the outer circumference of the nozzle and pass an electric current through the resistance wire to heat the tip of the nozzle.

[0004]

In such a device for ejecting gas from a nozzle in a vacuum and applying it to a metal surface for ionization, a metal wire heater is wound around the outer periphery of the nozzle to electrically heat the metal wire. When the line heater is heated, it often emits thermoelectrons and alkali ions, which may interfere with the measurement of the target sample component. The present invention aims to prevent the influence of thermoelectrons emitted from a metal wire heater.

[0005]

The ionizer of the present invention has a vacuum housing to be evacuated and an orifice having a small diameter located in the vacuum housing at the tip, and is introduced together with a light carrier gas. A nozzle that ejects a component gas together with a carrier gas from its orifice into a vacuum housing, and an electrode that is provided in the jet flow of the gas ejected from the orifice, is heated to a high temperature by energization, and ionizes the sample component in the jet by surface ionization. Department,
In the vacuum housing, a collector for detecting sample component ions ionized at the electrode portion, and in the vacuum housing, an infrared lamp and a condenser mirror for condensing infrared rays from the infrared lamp to the orifice portion are provided. And an infrared irradiation unit.

[0006]

Since the orifice portion of the nozzle is heated by infrared rays, there are no inconveniences such as the emission of thermoelectrons and the release of alkali ions as in the case of heating with a metal wire heater. Further, in the case of the metal wire heater, not only the nozzle tip portion but also an excessive portion other than the nozzle tip portion is heated. However, heating by infrared rays can heat only the nozzle tip portion by the condenser mirror.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment suitable for application to a gas chromatograph detector and the like. The tip of the nozzle 1 made of a heat-resistant material such as ceramic projects into a vacuum housing 11 that is evacuated by a vacuum pump through the vacuum exhaust port 12, and the nozzle has a diameter of 5 mm.
An orifice 1a having a minute diameter of 0 to 100 μm is opened. The sample component separated by the column of the gas chromatograph is sent to the nozzle 1 together with a light gas such as helium as a carrier gas, and is ejected from the orifice 1a into the vacuum housing 11 to be in a supersonic jet state. In the vacuum housing 11, an electrode portion 4 is provided which is provided in the jet flow of the gas ejected from the nozzle 1 and is inclined with respect to the advancing direction of the jet flow. The electrode unit 4 is energized by the electrode heating device 9 and controlled to have a high temperature of about 600 ° C. A ring-shaped collector having a wall surface inclined in the direction of the electrode portion 4 between the orifice 1a of the nozzle and the electrode portion 4 so as to receive ions generated by collision of the gaseous molecules ejected from the nozzle onto the electrode portion 4. 5 are arranged. The ions collected in the collector 5 are measured as a current by the electrometer 10.

In order to heat the nozzle tip portion 2 having the orifice 1a, an infrared light source 6 is arranged behind the electrode portion 4 as viewed from the orifice 1a, and the infrared ray from the infrared light source 6 is emitted to the nozzle tip portion 2 from the infrared light source 6. An infrared reflecting mirror 7 is arranged to focus the light on. The nozzle tip 2 is provided with a collar made of the same material as that of the nozzle 1 in order to improve efficiency of heating by infrared rays condensed by the infrared reflecting mirror 7 and applied to the nozzle tip 2 and to prevent unnecessary portions from being heated. A light receiving plate 3 having a shape of a circle is provided. The temperature of the nozzle tip portion 2 is detected by a temperature sensor 13 attached to the light receiving plate 3, and the detection signal is detected by a temperature control signal generator 14 provided outside the vacuum housing 11 to control the energization of the infrared light source 6. Infrared heating is controlled so that the nozzle tip portion 2 is guided to the external power source portion 8 and has a predetermined temperature.

In this embodiment, the vacuum housing 11 is evacuated by evacuating from the exhaust port 12, the electrode heating section 9 maintains the electrode section 4 at a predetermined high temperature, and the nozzle 1
The sample components are introduced together with the carrier gas and ejected from the orifice 1a into the vacuum housing 11. Electrode part 4
The ions of the sample component generated by colliding with the surface of the are collected by the collector 5 and measured as a current by the electrometer 10.

Although the embodiment of FIG. 1 shows an example applied to a detector of a gas chromatograph, the present invention can also be applied to an ion source of a mass spectrometer. Further, not only when the sample component gas ejected from the nozzle collides with the heated electrode portion to be ionized, but also the physical thin film forming device for depositing the sample component ejected from the nozzle on the substrate, and the ejection from the nozzle The present invention can be applied to various devices that utilize jetting of a sample component from a nozzle, such as a gas phase reaction device that causes a chemical reaction between the sample component gases.

FIG. 2 shows another shape of the nozzle tip. (A) shows a nozzle shape without using the light receiving plate 3 as shown in FIG. In (B), the light receiving plate 3 is further provided at the tip of the nozzle.

[0012]

According to the present invention, the infrared heater is placed in a position not related to the measurement in the vacuum apparatus, and the tip of the nozzle from which the sample component gas is ejected is locally heated by the infrared rays. There is no generation of extra thermoelectrons or ions, such as heating, and there is no obstruction to the measurement of ion electron flow. Since the tip portion of the nozzle can be locally heated by infrared heating, it is possible to prevent the heat from being transmitted from the nozzle to other portions, which may have an adverse effect.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment.

FIGS. 2A and 2B are cross-sectional views showing a nozzle tip portion in another embodiment together with an infrared heater.

[Explanation of symbols]

 1 Nozzle 1a Orifice 2 Nozzle tip part 3 Light receiving plate 4 Electrode part 5 Collector 6 Infrared light source 7 Infrared reflecting mirror 11 Vacuum housing

Claims (1)

[Claims] 1. A vacuum housing to be evacuated, and a fine-diameter orifice located in the vacuum housing at the tip, and a sample component gas introduced together with a carrier gas of light gas is evacuated from the orifice together with the carrier gas. A nozzle for ejecting into the housing, an electrode portion provided in the jet flow of the gas ejected from the orifice, heated to a high temperature by energization, and ionizing the sample component in the jet by surface ionization, are provided in the vacuum housing. An infrared ray having a collector for detecting sample component ions ionized at the electrode portion, an infrared lamp in the vacuum housing, and a condenser mirror for condensing the infrared ray from the infrared lamp to the orifice portion. An ionization device comprising: an irradiation unit.