# US 2013/0153762 A1 · Method and apparatus for ionizing gases using uv radiation and electrons and identifying said gases

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- Number: US 2013/0153762 A1
- Document ID: US20130153762A1
- Status: Published application
- Kind: A1
- Application number: 13/820,654
- Filed: 2011-08-11
- Published: 2013-06-20
- Earliest claimed: 2010-09-09
- Assignees: Airsense Analytics GmbH
- Inventors: Wolf Münchmeyer; Bert Ungethüm; Andreas Walte
- Web page: https://patentgrep.com/patent/US20130153762A1

## CPC

- H01J 49/10: Ion sources; Ion guns
- G01N 27/622: Ion mobility spectrometry
- G01N 27/64: using wave or particle radiation to ionise a gas, e.g. in an ionisation chamber
- H01J 27/205: {with electrons, e.g. electron impact ionisation, electron attachment}
- H01J 27/24: using photo-ionisation, e.g. using laser beam
- G01N 27/68: using electric discharge to ionise a gas
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

The invention relates to a method for ionizing and identifying gases, wherein the gases to be identified are ionized in a reaction chamber and the product ions are measured, wherein the measurement of the product ions takes place via electrical fields acting on the product ions and the detection is performed with a detector for ions. It is provided that ionization takes place via UV radiation, and that simultaneously or sequentially ionization by electrons takes place. The invention further relates to a device for ionizing and identifying gases, which includes an ion source chamber having an ion source and an ion mobility spectrometer. For this purpose, a partition between the ion source chamber and the ion mobility spectrometer has a UV-transparent window and a window permeable for electrons, wherein UV radiation and electron radiation can be generated in the ion source chamber with the ion source.

## Claims

### Claim 1

Method for identifying and ionizing gases, wherein the gases to be identified are ionized in a reaction chamber and the product ions are measured, wherein the measurement of the product ions takes place by exposing the product ions to electric fields and the detection is performed with a detector for ions, wherein the ionization is performed using UV radiation, and that simultaneously or sequentially an ionization with electrons is performed.

### Claim 2 (depends on 1)

Method according to claim 1, wherein the ionization is performed by accelerating the electrons electrically in a low pressure region and accelerating the electrons towards an electron window which is permeable for electrons, wherein the electrons penetrate the window and then generate ions in a high pressure region.

### Claim 3 (depends on 1)

Method according to claim 1, wherein the ionization is performed indirectly by accelerating the electrons electrically in a low pressure region and accelerating the electrons towards an electron window, where the electrons are strongly decelerated and produce bremsstrahlung, which is then used to produce ions in a high pressure region.

### Claim 4 (depends on 1)

Method according to claim 1, wherein the UV-radiation is generated with a gas discharge and that the electrons are extracted from the gas discharge by an electrode arrangement and focused onto the electron window.

### Claim 5 (depends on 1)

Method according to claim 1, wherein the electrons from an electron source, which is made of a filament or from one or more field emission tips, are d
a) accelerated towards an electron window, penetrate the window and/or generate bremsstrahlung, thereby ionizing molecules in the reaction chamber, and
b) are subsequently accelerated towards a second electron window, penetrate the window and generate in a high pressure chamber UV radiation, with the UV radiation passing through the UV-transparent windows and ionizing molecules in the reaction chamber.

### Claim 6 (depends on 1)

Method according to claim 1, wherein the ionization with electrons occurs discontinuously during the ionization with UV radiation by guiding the electrons onto the electron window only for specified times.

### Claim 7 (depends on 1)

Method according to claim 1, wherein the ionization with UV radiation and by electron bombardment occurs discontinuously, in that
a) the electrons are guided to the electron-permeable window and thus generate ions in the reaction chamber, and
b) thereafter the electrons are guided only for specified times onto the second electron window and these electrons produce in the gas chamber UV radiation through interaction with gases residing in the gas chamber, wherein the UV radiation then enters the reaction chamber through the UV-transparent window, so that ionization takes place either with electrons or with UV radiation, wherein with one of the two ionization types ionization takes place continuously, whereas the second ionization type is additionally briefly switched on.

### Claim 8 (depends on 1)

Method according to claim 1, wherein ionization with UV radiation and by electron bombardment occurs discontinuously and alternatingly within very short times, i.e. within a few milliseconds.

### Claim 9

Method according to wherein for identifying the substances, the spectra measured by ionization with UV radiation and the spectra measured by ionization with electron bombardment are considered in combination and the substances are identified using methods using database comparison.

### Claim 10

Device for ionizing and identifying gases, comprising an ion source chamber having an ion source and an ion mobility spectrometer, wherein a partition between the ion source chamber and the ion mobility spectrometer has a window transparent to UV radiation and a window permeable for electrons, wherein UV radiation and electron radiation can be generated by the ion source in the ion source chamber.

### Claim 11 (depends on 10)

A device according to claim 10, wherein a noble gas resides in the ion source chamber under optimum pressure for a gas discharge, in particular in the millibar range, and that a window made for example of magnesium fluoride or calcium fluoride, which is transparent to the UV radiation generated by the gas discharge, delimits the ion sources chamber with respect to a reaction chamber, and another window, the electron window, which is permeable for electrons and is made, for example, of silicon-nitride, diamond or beryllium, is located next to the window that is transparent for UV radiation, and that electrodes for accelerating and focusing the electrons from the gas discharge onto the window are arranged in the ion source chamber.

### Claim 12 (depends on 10)

A device according to claim 10, wherein a high vacuum is present in the ion source chamber, in particular at a pressure of less than 10−6 millibar, that the ion source chamber is delimited by two electron windows which are permeable for electrons, whereby a window is directly adjacent to the reaction chamber and the other window is adjacent to a high-pressure chamber, that a noble gas at a pressure greater than 0.1 bar resides in the high-pressure chamber, and that the high-pressure chamber abuts the reaction chamber with a window that is transparent to UV radiation.

### Claim 13 (depends on 10)

A device according to claim 10, wherein the electron window decelerates electrons and is transparent for bremsstrahlung and in particular is made of metal-coated beryllium.

### Claim 14 (depends on 10)

A device according to claim 10, wherein an electrode arrangement is disposed in the ion source chamber, wherein the electrode arrangement accelerates the electrons and transports the electrons towards the electron windows or deflects the electrons from these electron windows, respectively.

### Claim 15 (depends on 10)

A device according to claim 10, wherein an electron source, comprising a material having a low work function for electrons, is disposed in the ion source chamber and that one or more external light sources are positioned on the ion source chamber, which produce photons that release electrons at the electron source by way of the photoelectric effect.

### Claim 16 (depends on 10)

A device according to claim 10, wherein the UV-transparent window is not arranged in a plane with the electron window and that the two windows are arranged such that the UV radiation and the electrons and/or the bremsstrahlung can intersect in the reaction chamber.

### Claim 17 (depends on 10)

A device according to one claim 10, wherein the ion source chamber is coupled with the reaction chamber of an ion mobility spectrometer.

### Claim 18 (depends on 10)

A device according to claim 10, wherein the ion source chamber is coupled with the reaction chamber or with the inlet region of a mass spectrometer, respectively, in particular directly at an inlet capillary or at an inlet aperture.