CHEMILUMINESCENT METHOD AND APPARATUS

• US 3,749,929 A
• Filed: 10/07/1971
• Issued: 07/31/1973
• Est. Priority Date: 10/07/1971
• Status: Expired due to Term

• Current Assignee: George W. Wooten, Rumult Iltis, Victor L. Johnson
• Original Assignee: George W. Wooten, Rumult Iltis, Victor L. Johnson
• Inventors: Wooten, George W., Iltis, Rumult, Johnson, Victor L.
• Primary Examiner(s): Lawrence, James W.
• Assistant Examiner(s): Nelms, D. C.
• Application Number:
  US05/187,265
• Time in Patent Office: 663 Days
• Field of Search: 250/83CD,217 23/232R,232E,254R,254E,23PC 73/73
• US Class Current: 436/172
• CPC Class Codes: G01N 21/766 of gases
• CPC Class Codes: Y10T 436/179228 Both nitrogen oxide and dioxide
• CPC Class Codes: Y10T 436/186 Sulfur dioxide

Abstract

The invention is a chemiluminescent method and apparatus for detecting NOx (NO and NO2), SO2, CO and other gases which react with atomic oxygen to produce chemiluminescence. Atomic oxygen generated by pulse electrical discharge is added at a controlled and known flow rate to a reaction chamber to which is also added at a controlled and known flow rate a gas mixture to be analyzed. The reaction chamber is maintained at a sufficient pressure to support chemiluminescence, normally above about 0.1 Torr and in the range of about 0.5 to 5.0 Torr. Photoelectric means is used to measure the chemiluminescence, and the photoelectric means is synchronized with the pulse discharge so that photoelectric means is turned off during the time of a pulse and for sufficient time thereafter to allow the light generated by the pulse discharge to disappear, whereby the only light the photoelectric means sees is chemiluminescence. The reaction zone and the oxygen generating means are compact and are located adjacent one another to allow miniaturization of the equipment.

Claims

2. A method of claim 1 wherein said electrical discharge is pulsed at a rate of from 1 pulse per second to 10 pulses per second, and the duty cycle of said pulses is 10 percent or less.

3. In an apparatus for measuring chemiluminescence in gases including means to produce atomic oxygen, a reaction zone including means to maintain pressure in said zone sufficient to support chemiluminescence, means to introduce atomic oxygen into said zone, means to introduce into said zone a gas mixture for analysis and means to detect the quantity of chemiluminescent light generated, the improvement comprising pulse discharge means for producing atomic oxygen and photoelectric means to detect the quantity of chemiluminescent light generated by the gas mixture and atomic oxygen mixed in said zone, said photoelectric means being synchronized with said pulse discharge means so said photoelectric means is turned off until the light generated by said pulse discharge means has disappeared and thus only chemiluminescent light is measured.

4. A miniaturized apparatus of claim 3 wherein said pulse discharge means produces from 1 to 10 pulses per second, the duty cycle of said pulses is 10 percent or less, and said means to produce atomic oxygen and said reaction zone are located adjacent each other and are made as small as possible.