Abstract A method and system for detecting extremely low concentrations of polynitro vapors such as tri-nitrotoluene (TNT) or nitroglycerine (NG) in which an air sample under investigation is introduced into a reaction chamber and mixed with a negatively ionized gas in the reaction chamber to transfer electrons to NG and TNT molecules in the air sample. A drift field is applied to the mixture in the reaction chamber to transport negative ions therein in a desired direction out of the reaction chamber. The thus transported ions are then mass filtered to separate out NG and TNT ions. The NG and TNT ions impinge upon means such as an electron multiplier for producing an electrical current, with the electrical current providing an indication of the NG and TNT concentrations in the air sample.
A METHOD FOR DETECTING CONCENTRATIONS OF POLYNITRO MOLECULES IN AN AIR SAMPLE COMPRISING THE STEPS OF INTRODUCING AN AIR SAMPLE WHICH IS NOT IONIZED INTO A REACTION CHAMBER, PROVIDING A SINGLE NEGATIVELY IONIZED GAS IN THE REACTION CHAMBER WHEREBY THE IONIZED GAS MIXES WITH THE AIR SAMPLE, SAID NEGATIVELY IONIZED GAS HAVING AN ELECTROL AFFINITY GREATER THAN THAT OF NORMAL ATMOSPHERIC CONSTITUENTS AND LESS THAN THAT OF POLYNITRO COMPOUNDS OF NG OR TNT WHEREBY SAID INOIZED GAS SELECTIVELY TRANSFERS ELECTRONS WHEREBY THE POLYNITRO MOLECULES IN THE AIR SAMPLE TO FORM NEGATIVE IONS THEREOF, APPLYING A DRIFT FIELD TO THE MIXTURE IN THE REACTION CHAMBER TO TRANSPORT THE NEGATIVE IONS THEREIN IN A DESIRED DIRECTION OUT OF THE REACTION CHAMBER, MASS FILTERING THE THUS TRANSPORTED IONS TO SEPARATE OUT POLYNITRO IONS, GENERATING AN ELECTRICAL CURRENT BY THE POLYNITRO IONS, AND MEASURING THE ELECTRICAL CURRENT TO PROVIDE AN INDICATION OF THE POLYNITRO CONCENTRATION IN THE AIR SAMPLE.
Claim 2
Independent Claim
155 words
A METHOD FOR DETECTING CONCENTRATIONS OF POLYNITRO MOLECULES IN AN AIR SAMPLE COMPRISING THE STEPS OF INTRODUCING AN AIR SAMPLE WHICH IS NOT IONIZED INTO A REACTION CHAMBER, PROVIDING A SINGLE NEGATIVELY IONIZED GAS IN THE REACTION CHAMBER WHEREBY THE IONIZED GAS MIXES WITH THE AIR SAMPLE, SAID NEGATIVELY IONIZED GAS HAVING AN ELECTROL AFFINITY GREATER THAN THAT OF NORMAL ATMOSPHERIC CONSTITUENTS AND LESS THAN THAT OF POLYNITRO COMPOUNDS OF NG OR TNT WHEREBY SAID INOIZED GAS SELECTIVELY TRANSFERS ELECTRONS WHEREBY THE POLYNITRO MOLECULES IN THE AIR SAMPLE TO FORM NEGATIVE IONS THEREOF, APPLYING A DRIFT FIELD TO THE MIXTURE IN THE REACTION CHAMBER TO TRANSPORT THE NEGATIVE IONS THEREIN IN A DESIRED DIRECTION OUT OF THE REACTION CHAMBER, MASS FILTERING THE THUS TRANSPORTED IONS TO SEPARATE OUT POLYNITRO IONS, GENERATING AN ELECTRICAL CURRENT BY THE POLYNITRO IONS, AND MEASURING THE ELECTRICAL CURRENT TO PROVIDE AN INDICATION OF THE POLYNITRO CONCENTRATION IN THE AIR SAMPLE.
Claim 3
Dependent Claim
31 words
A method in accordance with claim 1 wherein the negatively ionized gas has an electron affinity greater than one electron volt but less than the electron affinity of NG and TNT.
Claim 4
Dependent Claim
14 words
A method in accordance with claim 2 wherein the negatively ionized gas is SF6.