# US 2009/0260417 A1 · Methods and systems for analyzing a volume of gas > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2009/0260417 A1 - Document ID: US20090260417A1 - Status: Published application - Kind: A1 - Application number: 12/104,125 - Filed: 2008-04-16 - Published: 2009-10-22 - Earliest claimed: 2008-04-16 - Assignees: Infineon Technologies AG - Inventors: Werner Weber; Rudolf Lachner - Web page: https://patentgrep.com/patent/US20090260417A1 ## CPC - G01N 21/3504: for analysing gases, e.g. multi-gas analysis - G01N 21/6404: {Atomic fluorescence} - G01N 2021/1793: {Remote sensing} - 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 One embodiment relates to a method for determining a concentration of a molecular species of interest. In this method, electromagnetic radiation is transmitted into a volume of gas within an output exhaust system. The transmitted electromagnetic radiation has a first intensity at a characteristic frequency that is associated with a transition of the molecular species of interest. Electromagnetic radiation is then received from the volume of gas at a second intensity. The method then correlates the first intensity to the second intensity to determine the concentration of the molecular species of interest within the volume of gas. Other methods and systems are also disclosed. ## Claims ### Claim 1 A method for determining a concentration of a molecular species of interest, comprising: transmitting electromagnetic radiation into a volume of gas within an output exhaust system, where the transmitted electromagnetic radiation has a first intensity at a characteristic frequency that is associated with a transition of the molecular species of interest; receiving electromagnetic radiation from the volume of gas at a second intensity; and correlating the first intensity to the second intensity to determine the concentration of the molecular species of interest within the volume of gas. ### Claim 2 (depends on 1) The method of claim 1, where the molecular species of interest comprise at least one of: nitrous oxide (NOX) molecules or ammonia molecules. ### Claim 3 (depends on 1) The method of claim 1, where the electromagnetic radiation is transmitted along a transmission path and where receiving the electromagnetic radiation comprises: receiving the electromagnetic radiation along the transmission path at the characteristic frequency. ### Claim 4 (depends on 1) The method of claim 1, where receiving the electromagnetic radiation comprises: receiving the electromagnetic radiation at another characteristic frequency that differs from the characteristic frequency. ### Claim 5 (depends on 1) The method of claim 1, further comprising: reflecting the transmitted electromagnetic radiation multiple times through the volume of gas to enhance a difference between the first intensity and the second intensity. ### Claim 6 (depends on 1) The method of claim 1, further comprising: transmitting a control signal that facilitates a change in engine control based on the concentration of the molecular species of interest. ### Claim 7 A method for determining a concentration of a molecular species of interest, comprising: transmitting electromagnetic radiation into a volume of gas; receiving electromagnetic radiation from the volume of gas; and correlating the transmitted electromagnetic radiation to the received electromagnetic radiation to determine the concentration of the molecular species of interest within the volume of gas. ### Claim 8 (depends on 7) The method of claim 7, where the molecular species of interest comprises at least one of: nitrous oxide (NOX) molecules or ammonia molecules. ### Claim 9 (depends on 7) The method of claim 7, where a receive frequency at which the electromagnetic radiation is received is adjusted in time. ### Claim 10 (depends on 7) The method of claim 7, where a transmit frequency at which the electromagnetic radiation is transmitted is adjusted in time. ### Claim 11 (depends on 10) The method of claim 10, where a receive frequency at which the electromagnetic radiation is received is synchronously adjusted in time with the transmit frequency. ### Claim 12 (depends on 10) The method of claim 10, where a receive frequency at which the electromagnetic radiation is received is adjusted in time independent of the transmit frequency. ### Claim 13 A gaseous monitoring system, comprising: a frequency-tunable transmitter adapted to transmit electromagnetic radiation through a volume of gas that includes a molecular species of interest, where the electromagnetic radiation has a first intensity at a characteristic frequency associated with the molecular species of interest; and a frequency-tunable receiver adapted to generate a time-varying voltage or current based on a second intensity at which the transmitted electromagnetic radiation is received through the volume of gas. ### Claim 14 (depends on 13) The system of claim 13, where the transmitter comprises: a transmit antenna; transmission semiconductor circuitry coupled to the transmit antenna; and frequency tuning circuitry adapted to adjust a frequency at which the electromagnetic radiation is transmitted. ### Claim 15 (depends on 13) The system of claim 13, where the receiver comprises: a receive antenna; reception semiconductor circuitry coupled to the receive antenna; and frequency tuning circuitry adapted to adjust a frequency at which the electromagnetic radiation is received. ### Claim 16 (depends on 13) The system of claim 13, where the receiver is aligned along a transmission path on which the electromagnetic radiation is to be transmitted. ### Claim 17 (depends on 13) The system of claim 13, where the receiver is off of a transmission path on which the electromagnetic radiation is to be transmitted. ### Claim 18 A gaseous monitoring system, comprising: a frequency-tunable transmitter, comprising: a transmit antenna; transmission semiconductor circuitry coupled to the transmit antenna and adapted to facilitate transmission of electromagnetic radiation at a first intensity at a characteristic frequency associated with a molecular species of interest; and frequency tuning circuitry adapted to adjust a frequency at which the electromagnetic radiation is transmitted. ### Claim 19 (depends on 18) The system of claim 18, further comprising: a receiver, comprising: a receive antenna separated from the transmit antenna by a volume of gas; and reception semiconductor circuitry coupled to the receive antenna and adapted to generate a time-varying voltage or current based on a second intensity with which the transmitted electromagnetic radiation is received at the receive antenna in time. ### Claim 20 (depends on 19) The system of claim 19, where the receiver further comprises: processing circuitry adapted to correlate the first intensity to the second intensity to detect a concentration of the molecular species of interest in the volume of gas. ### Claim 21 (depends on 20) The system of claim 20, further comprising: a cavity resonator in which the volume of gas resides. ### Claim 22 (depends on 20) The system of claim 20, further comprising: at least two reflective surfaces arranged about a periphery of the volume of gas and cooperatively adapted to reflect the transmitted electromagnetic radiation through the volume of gas multiple times before the electromagnetic radiation reaches the receive antenna. ### Claim 23 (depends on 19) The system of claim 19, where the receiver further comprises: frequency tuning circuitry adapted to adjust a frequency at which the electromagnetic radiation is received. ### Claim 24 (depends on 19) The system of claim 19, where at least one of the transmission semiconductor circuitry and reception semiconductor circuitry is adapted to operate at a frequency that falls within a frequency range of about 1 GHz to about 10 THz. ### Claim 25 A gaseous monitoring system, comprising: transmitting means for transmitting electromagnetic radiation at a first intensity and at a characteristic frequency associated with a molecular species of interest; and receiving means for generating a time-varying voltage based on a second intensity at which the transmitted electromagnetic radiation is received in time; a volume of gas separating the transmitting means from the receiving means; and processing means for correlating the first intensity to the second intensity to determine the concentration of the molecular species of interest in the volume of gas.