FR2568376A1 - CHEMOLUMINESCENCE ANALYSIS METHOD AND DEVICE - Google Patents

Abstract

IN A DEVICE FOR ANALYSIS OF CHEMOLUMINESCENT SUBSTANCES, A FIRST REACTION CHAMBER 3 IS PROVIDED WITH A DUCT 2 FOR INTAKE A SAMPLING GAS, WITH A DUCT 1 FOR OZONE INTAKE AND AN ORIFICE EXIT TO A SECOND REACTION CHAMBER 4. THE INLET DUCTS 1, 2 CAN BE GROUPED JUST BEFORE THE ENTRY PORT IN THE FIRST BEDROOM 3. THE SECOND BEDROOM 4 HAS A GAS MIXTURE COMING FROM THE FIRST CHAMBER 3, FROM AN OUTLET TO EVACUATE THIS GAS MIXTURE, A DETECTOR 7 OF THE RADIATION ENERGY, AS WELL AS A WINDOW 5 INTERCALED BETWEEN THE SAID CHAMBER 4 AND THE DETECTOR 7, AND WHOSE MATERIAL IS TRANSLUCENT.

Description

CHEMOLUMINESCENCE ANALYSIS METHOD AND DEVICE

  The present invention relates to a method and a device.

  positive chemiluminescence analysis.

  The electronic industries involved in the manufacture of semiconductors and similar objects make use of large

  quantities of toxic gases such as silane, arsine, phosphi-

  ne, diborane, etc. The maximum permissible concentrations of these gases in a working environment are very low and are, for example for Japan, 5 ppm for silane, 0.05 ppm for arsine, 0.3 ppm for phosphine and

  0.1 ppm for diborane. Because the semi-industrial

  drivers are experiencing increasing prosperity, this prosperity is accompanied by the growing need for a leak detector or an analysis device capable of detecting and analyzing,

  easily and precisely, such toxic gases in a

  working environment. Conventionally, such gases

  have been determined by various well known methods, among the-

  which we can cite photometric analysis by infrared, photometry by chemical reaction / atomic absorption,

  galvanic membrane cell process, electrolysis at

  tential controlled, chemiluminescence analysis, and the like.

  Among the aforementioned measurement principles, chemilumines-

  cence is a radiation energy which is generated when a substance (molecule) in excited condition, whose formation

  results from a chemical reaction, falls back to its ground state.

  Although the phenomenon of chemiluminescence has been known for a long time, the recent development of measurement technologies

  low light, for example photo multipliers

  electrons and similar devices, attracted more attention

  attention to an analytical process based on chemilu-

  minescence. Since the essential characteristic of this

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  analytical process not only consists of a great sensi-

  but also in additional advantages such as a wide range of linear reactions, easy operation, rapid reaction, simple device design and the like, the scope of this pro-

  ceded has grown in recent years.

  Among these chemiluminescent phenomena, chemilumines-

  Cence in the presence of ozone is known in combination with components (such as CO, THC, S02, NO, etc.) of atmospheric air, combustion gases and automobile exhaust gases,

  as well as with inorganic hydrides as described above

  above. Regarding the devices implementing

  the chemiluminescence process, the "Thermo Electron Corp."

  (United States of America) and other manufacturers have already, after years of studies, obtained good commercial results in the supply of nitrogen oxide analyzers

  in atmospheric air, flue gases and exhaust gases

  ment of automobiles. However, until very recently, the chemiluminescence method had not been applied to

analysis of inorganic hydrides.

  The application, to the detection of inorganic hydrides in a working environment, of the appropriate technology for

  nitrogen oxide analyzers, raises difficulties.

  Usually, a work environment contains

  our quantities of THC, CO, SO2, NO and analogous substances

  gues. Among other things, NO raises a serious problem, because it confers a strong chemiluminescent intensity and it

  exists in high concentrations. Therefore, this NO mani-

  plagues chemiluminescence together with inordinate hydrides

  ganics to be detected, interfering with the dosage of these. It is therefore necessary to distinguish between chemiluminescence from hydrides

  inorganic and chemoluminescence caused by pre-NO

  feels in a work environment.

  Japanese patent application no. 196138/82 subject to public inspection (filed in the name of "L'AIR LIQUIDE SOCIETE ANONYME", France, with priority claim of the application

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  French Patent No. 8,110,316 filed May 25, 1981) describes

  a method and a device for detecting inorganic hydrides

  ques taking advantage of the difference between the beaches of lon-

  wavelengths of the chemiluminescent spectrum resulting from the reaction of NO with ozone, and chemiluminescent spectra

  resulting from reactions of inorganic hydrides with ozone.

  Specifically, the light emitted as a result of the chemiluminescent reactions passes through a filter transmitting light in the wavelength range between 495 nm and 650 nm, then the resulting filtered light is detected, inorganic hydrides being able to be detected by eliminating the interference from NO. The chemiluminescent spectrum

  of the NO has a spectral distribution covering the in-

  infrared from 600 nm to 3000 nm, while that of arsine is

  is between 300 nm and 900 nm and that of phosphine is com-

  taken between 350 nm and 750 nm. Therefore, interference due to NO can be rationally eliminated by using an appropriate filter to adequately reduce the wavelength range of the filtered light. However, this method suffers from the disadvantage that the absorption of light by

  the filter inevitably causes a loss of photo-

  metric and therefore a decrease in the sensitivity of

detection of inorganic hydrides.

  The present invention has been developed with care

  to the fact that the chemiluminescent reactions of various compounds

  chemiluminescent health with ozone have different durations.

  Specifically, the chemiluminescence of NO begins when it comes into contact with ozone and ends in an instant (its duration

  being several milliseconds or less), while the chi-

  mioluminescence of inorganic hydrides (such as silane, arsi-

  ne, phosphine, diborane, etc.) in the presence of ozone lasts a significant period of time (several seconds). To exploit this phenomenon, the inventors have carried out extensive studies

  which have led to the present invention.

  In accordance with one aspect of the present invention,

  a method for analyzing chemiluminal substances is proposed.

  nescents, according to which the radiation energy emitted consecu-

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  tive to the chemiluminescence reaction of a substance

  chemiluminescent in the presence of ozone in a sample gas

  lonnage, is detected by a detector, this process being

  characterized by the fact that the instant at which the sample gas

  lonnage is mixed with ozone, in order to trigger the chemiluminescent reaction, precedes at least one of the moments at which

  the radiation energy resulting from this chemilu-

  downward is detected by the detector.

  In the process of the present invention, the step consisting

  O both to detect, using a probe, the radiation energy

  resulting from the chemiluminescent reaction, should not require

  Obviously be limited to one time, but can be performed two or more times twice at appropriate intervals. When this step takes place two or more than two different times, one of these occurrences may coincide with the time at which the

  chemiluminescent reaction is initiated. However, he was born

  that the time at which a sample gas is mixed

  dipped in ozone, to trigger the reaction of chemilumines-

  cence, precedes at least one of the instants at which the radiation energy resulting from this chemiluminescent reaction is

detected by a probe.

  The present invention also relates to a device, the use of which directly implements the method according to the invention as described above. Specifically, according to

  Another aspect of the present invention, there is provided a dis-

  chemiluminescent test positive, which includes two or more chemiluminescent reaction chambers

  arranged in series and is characterized in that the first

  re reaction chamber is provided with a conduit allowing there

  introduce a sampling gas, a conduit for intro

  draw off ozone and an outlet to discharge the

  gas mixture in the second reaction chamber, the

  respective sampling gas inlet and

  ozone can possibly be grouped just before the ori-

  inlet to the first reaction chamber; and by the fact that the other chamber, or second chamber, is provided with an inlet orifice allowing the gas mixture to be introduced therein

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  coming from the preceding reaction chamber of an outlet orifice for discharging the gas mixture in the following reaction chamber or outside the device, from a probe for detecting the radiation energy resulting from the chemiluminescent reaction s' operating in the room, as well as a window whose material is transparent to light and which

  is interposed between the reaction chamber and said probe.

  In the device of the present invention, it is not essential to provide the first reaction chamber with a

  probe detecting radiation energy resulting from chemo

  luminescence occurring in this reaction chamber. He.

  will nevertheless appear obvious that it is not excluded that

  per the first reaction chamber of a detector.

  The invention will now be described in more detail by way of non-limiting examples, with reference to the appended drawings in which:

  FIG. 1 is a schematic section illustrating a form

  me of realization of the device of the present invention; FIGS. 2A and 2B are respectively a section observed laterally and a section in plan, representing the structure of the reaction chamber and of its associated parts in another embodiment of the device according to the invention 6 and FIG. 3 is a section schematic showing another

  variant embodiment of the device according to the invention.

  Chemiluminescent substances suitable for analysis

  by the process according to the present invention are inorganic hydrides such as silane, arsine, phosphine, diborane and the like. Among others, arsine and phosphine are the most suitable compounds. The chemiluminescent reactions of these substances in the presence of ozone last

  for several seconds, while the chemilumines reaction-

  cent of NO begins when it comes into contact with ozone and ends in an instant (having lasted several milliseconds

  or less). Therefore, if the time at which the sample gas

  tillonnage is mixed with ozone, to cause reactions

  chemiluminescent, slightly precedes the moment at which the

  radiation, emitted as a result of these chemo-

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  luminescent, is detected by a probe, chemiluminescence

  caused by the aforementioned inorganic hydrides can be se-

  lectively detected since the chemiluminescence due

  any amount of NO present in this sample gas

  lonnage has completely faded. For example, in the case

  of a quantity of NO contained by atmospheric air, energizing it

  radiation resulting from the chemiluminescence of this NO

  usually fades (to a practically indefinite level

  celable) after 2 to 5 milliseconds after the initiation of the chemiluminescent reaction by contact with ozone, although this duration may vary more or less in

  depending on the conditions at the time of this contact.

  Because the radiation energy resulting from the chemo-

  long-lasting luminescence of inorganic hydrides decreases

  gradually it is better, in order to selectively detect

  tively this only radiation energy from the chemiluminescence of inorganic hydrides, that the time at which the energy is detected by the probe is set at between 2 and 5 milliseconds (optimally about 3 milliseconds) after

  the time at which the chemiluminescent reactions started.

  In another embodiment, when an exchanging gas

  tillonnage is mixed with ozone to trigger chemiluminescence reactions, the radiation energy resulting from these reactions is detected by a probe with an adequate time interval, i.e. at the same time as the triggering of chemiluminescent reactions or at a moment slightly more

  late. In this way, the radiation energy from all

  The chemiluminescent substances are detected at the first instant, and the radiation energy coming only from the substances whose chemiluminescent reaction is long lasting is detected at the second instant. Thus, it is possible to analyze the respective chemiluminescent substances on

the basis of two measured values.

  In addition, among the chemical substances whose chemiluminescent reaction lasts several seconds, this duration varies according to the compound considered. Therefore, chemicals contained in the sample gas can be

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  isolated and analyzed with greater acuity, detecting

  the radiation energy at three or more than three different instants

  and by comparing the results of this measurement. The concentration of ozone, necessary according to the present invention in the chemiluminescent reaction zone, varies according to the sensitivity of the detector used, the amount

  of the substance to be detected, and analogous factors.

  However, it is preferable to use ozone, the con-

  centration represents 0.1% by volume, or more. It is obvious

  that if a detector with greater sensitivity is used

  bility, the present invention can also be implemented

  with lower ozone concentrations.

  When practicing the present invention, the con-

  minimum detectable centering of the substance to be detected

  not only depends on the type of substance to be detected,

  but also measurement conditions such as sensitivity

  t of the detector used, and other similar parameters. When-

  that the substance to be detected is an inorganic hydride

  and that the detector consists of a photo- multiplier

  electrons with high sensitivity, mini concentration

  detectable male is 1 ppb or less for arsine, 18 ppb or less for phosphine, 100 ppb or less for diborane and

500 ppb or less for silane.

  The detector used for practicing the present invention may suitably consist of a photoelectron multiplier, a photosensitive semiconductor, or the like. It is now appropriate, with reference to the accompanying drawings,

  describe several specific embodiments of the provision

  sitive for implementing the method according to the present invention

  tion. Figure 1 is a schematic section showing one of the embodiments of the device of the invention. In this figure, the reference numeral 3 designates a first chamber

  reaction chamber, so to speak, a pre-

  reaction. This first chamber 3 is provided with a conduit 2 per-

  putting in a sample gas and a conduit

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  1 to introduce ozone, these conduits being grouped just

  before the intake port of this first reaction chamber

  tion 3. As soon as the two gases are introduced through their conduits

  respective and mixed in the first chamber 3, the substan-

  these chemiluminescent contained by the sample gas manifest chemiluminescence. Chemiluminescence of

  short time from NO present in the sample gas

  ge completely faded from the moment that the mixture

  zeux enters a second reaction chamber 4. On the other hand, --o the long-term chemiluminescence originating from inorganic hydrides persists somewhat in the second chamber 4. The resulting light passes through an optical window 5 consisting of quartz or a transparent quartz glass in the entire wavelength range exceeding 170 nm, then this light reaches a detector 7. Thus, the chemiluminescence analysis of inorganic hydrides present in the sampling gas

  can be executed without being affected by interference from

  nant du No. In the device of Figure 1, the first chamber of

  reaction 3 and the second reaction chamber 4 are mutual-

  ment connected by an intermediate pipe 8. Obviously, it is however possible to also provide an arrangement devoid of the pipe 8 and illustrated in Figures 2A and 2B. These FIGS. 2A and 2B are sections observed respectively in elevation and in plan, showing the structure of the reaction chamber and of its associated parts in another

  type of embodiment of the device of the present invention.

  In this embodiment, the outlet of the first chamber

  reaction bre 3 is directly connected to the inlet port

  second reaction chamber 4.

  Figure 3 is a schematic section showing another alternative embodiment of the device according to the invention. This FIG. 3 illustrates a first reaction chamber 3 provided with a pipe 1 allowing the introduction of a sampling gas therein, a pipe 2 for introducing ozone therein, as well as a pipe 8 delivering the mixture gas at a second reaction chamber 4. Light, resulting from chemiluminescence

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  operating in the first reaction chamber 3, passes through an optical window 5 and reaches a detector 7 generating an electrical signal 11. When the gas mixture is introduced into

  the second chamber 4 through the conduit 8, the light, resulting -

  long-term chemiluminescence which continues to operate, passes through an optical window 9 and reaches a detector 10 which generates an electrical signal 12. An electrical signal 13

  is obtained by subtracting the electrical signal 12 from the electrical signal

  trique 11. An arrangement of this kind makes it possible to detect, under

  the shape of the respective electrical signals 12 and 13, the quantities

  tities of long-lasting chemiluminescence substances (such as inorganic hydrides) and chemiluminescence substances

  short-lived (such as No) enclosed by sample gas

  lonnage. In the device according to the present invention, no limitation is imposed on the photometric spectrum allowing the

  measurement, and it is possible to use a window whose material

  riau (like quartz or quartz glass) is transparent across the entire wavelength range. This eliminates the loss of photometric intensity due to the absorption of light by an optical filter as used in the invention according to the request.

  cited above no. 196138/82, and this confers a noticeable improvement

  ble detection sensitivity.

Example

  Using two types of devices as illustrated

  in FIGS. 2A and 2B, the analysis was carried out by chemo

  luminescence of nitrogen gas containing 0.5 ppm of phosphine,

  nitrogen gas containing 3.74 ppm NO and nitrogen gas containing

  closing 0.5 ppm of phosphine and 3.74 ppm of No. The ratings are

  tees in Figures 2A and 2B were chosen as follows: a = 10 mm, b = 30 mm and c = 13 mm. The dimension t was 0 mm in one of the devices (i.e. the first chamber

  was suppressed), and 52.5 mm in the other device

  tif. Detector 7 consisted of a photo- multiplier

  electrons and its output signal had passed through a conver-

  current weaver in voltage to obtain an output voltage.

  First, using the device in which the

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  first reaction chamber had been removed, a sample gas

  tillonnage was introduced into the reaction chamber through line 1 at a flow rate of 155 ml / min, and air containing 0.3% by volume of ozone was introduced into this chamber, through line 2, at a flow rate of 120 ml / min. The absolute pressure which

  gn in the reaction chamber was about 2.79. 104 Pa.

  Under these conditions, the radiation energy resulting from the chemiluminescence was detected by the detector 7. When the output signal of this detector was 100 for the sample gas containing 0.5 ppm of phosphine (the applied voltage at the photoelectron multiplier was set so that this output signal became 1 V), the sample gas containing 3.74 ppm NO gave an output signal of 93.5 and the sample gas containing both

  phosphine and NO gave an exit signal of 193.

  This indicated that the presence of NO seriously hampered the

phosphine detection.

  Then, using the device fitted with the first reaction chamber (-Z 52.5 mm), experiments were carried out with the same flow rates and under the same pressure prevailing in the reaction chambers. The detector output for the sample gas containing 0.5 ppm phosphine was 59.5, indicating that chemiluminescence was continuing

  in the second reaction chamber. However, the chemilumi-

  sample gas containing 3.74 ppm NO had

  completely gone, and caused an exit signal from the detector

  whose value was as low as 0.6. The sample gas

  tonnage containing both phosphine and NO gave a detector output almost equivalent to that of the sample gas containing only phosphine. That

  indicated that, if measurements are made under these conditions

  tions, only phosphine can be analyzed without being affected

by interference from NO.

  Similar experiments were carried out under the same conditions as those described above, except that air containing 0.3% by volume of ozone was introduced by

  line 1 at a flow rate of 120 ml / min, and that a sample gas

  ii 2568376 lonnage was introduced via line 2 at a flow rate of 155 ml / min. In this case too, the results indicated that, if measurements are made using the device with

  the first reaction chamber (t = 52.5 mm), only the phosphi-

  cannot be selectively detected and analyzed without undergoing

NO interference.

  It goes without saying that many modifications can be made to the method and to the device described and shown,

  without departing from the scope of the invention.

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Claims (8)

  1. Method for the analysis of chemiluminescent substances, according to which the radiation energy emitted after   the chemiluminescence reaction of a chemiluminescent substance-   cente in the presence of ozone, in a sampling gas, is detected by a detector, process characterized by the fact that the instant at which the sampling gas is mixed with ozone, in order to trigger the chemiluminescent reaction,   precedes at least one of the instants at which the energy of ray-   resulting from this chemiluminescent reaction is detected by said detector.   2. Method according to claim 1, characterized by the   fact that the chemiluminescent substance is an abnormal hydride   ganic. 3. Method according to claim 2, characterized by the   fact that the inorganic hydride is arsine.   4. Method according to claim 2, characterized by the   fact that the inorganic hydride is phosphine.   5. Method according to claim 1, characterized in that the instant at which the radiation energy is detected   by the detector is delayed by 2 to 5 milliseconds from the ins-   as long as the chemiluminescent reaction is initiated.   6. Device for analyzing chemiluminescent substances,   comprising two or more than two chemilu-   minescente arranged in series and characterized in that the first reaction chamber (3) is provided with a conduit (2) for introducing a sampling gas therein, with a conduit (1) for introducing therein ozone and an outlet for discharging the gas mixture into the second reaction chamber   (4), the respective conduits (2, 1) for admitting the sample gas   tillonnage and ozone which can possibly be combined   just before the inlet to the first reaction chamber   tion (3); and by the fact that the other chamber, or second chamber (4), is provided with an inlet orifice making it possible to introduce therein the gaseous mixture coming from the preceding reaction chamber (3), with an orifice outlet for discharging the gas mixture into the next reaction chamber or outside the device, 13 2568376   a detector (7) for detecting the resulting radiation energy   both of the chemiluminescent reaction taking place in this reaction chamber (4), as well as of a window (5) whose material is transparent to light, and which is interposed between the reaction chamber (4) and said detector (7). 7. Device according to claim 6, characterized in that the material constituting the window (5) is quartz or quartz glass.   8. Device according to claim 6, characterized in that the first reaction chamber (3) is also provided   a detector (7) for detecting the radiation energy   resulting from the chemiluminescent reaction taking place in this chamber (3), as well as a window (5) whose material is transparent to light, and which is interposed between said   reaction chamber (3) and said detector (7).