T:+441235567357Einfo@mirico.co.uk-W:www.mirico.co.uk

Technology Note

Laser Isotope Ratiometer A field deployable high precision Stable Isotope Analyser About:TheLaserIsotopeRatiometer(LIR)isanewinnovativetechniqueusedtomeasuretheratioofstableisotopesofagivenmolecule.Thecurrentsystemhasbeendemonstratedfor13C:12C(δ13)analysisinCO2.Theinstrumentisdesignedtoofferhighprecision,realtimemeasurementsinacompactandrobustpackage.Theinstrumentwasdesignedtoincludeanon-boardcalibrationsystemforautonomousoperationandenhancedstabilityandaccuracy.LaserbasedtechniqueshavebeendevelopedthatovercomeseverallimitationsofIRMSincludingrealtimeanalysisandportability.However,lasertechniquesdevelopedto-datecommonlyapplyhighprecisionopticalcavitiesasthebasisofoperationwhichrelyonhighreflectivityopticsinordertoachievenearequivalentprecisionasIRMS.Thisaddsconsiderablecomplexityandintroduceslimitationsintermsofsamplehandlingandrobustnesstothesystemdesign.TheLIRusestheadvantagesoftheMid-IRandaninnovativeopticaldesigntoachieveperformancewithoutcompromisetorobustness.Advantages:TheLIRbringssimplicitytostableisotopeanalysis,whetherinthefieldorinalaboratoryenvironment.Theinstrument’sdesignoriginatedaspartofaEuropeanSpaceAgencyprogrammetodemonstratetheLIRforplanetarylanders.Overallthedesignofferscompactness,robustnessandprecisionwithouttheneedforaskilledoperatororexcessiveuseofconsumables.< Fielddeployableanalysercapableofrealtimed13CforCO2.

< Builtinauto-calibrationsystem,farreducedoperationcostsandmaintenance.

< Builtinreferencesystemsensuresstabilityandaccuracyovergreaterperiodoftime.

< Highprecision,<0.15‰in35smeasurement.

< Compact&robust,suitableforfielddeployment.

< Platformsystemthatcanbeconfiguredforotherstableisotopesusingthesameprinciples.

Key Features < High precision and accuracy

< Fast measurements

< Highly robust, field deployable

< Built in permanent calibration

Applications < Environmental Science

< Medical Diagnosis

< Mud Gas Isotope Logging

T:+441235567357Einfo@mirico.co.uk-W:www.mirico.co.uk

Technology Note

OperatingPrinciples:Figure1belowillustratestheprinciplesofoperation.1)Twolasersofwavelengthλ1andλ2,probe

13CO2and12CO2.The

wavelengthsareselectedforoptimummeasurementsoftheisotopesandequaltemperaturedependence.2)Lasersprobethegassample,atthesametimelasersprobeareferencemixture.3)Afastopticalswitchflicksthebeambetweenthegassampleprobeandreferencechamberprobeatarategreaterthan10KHz.Detectorsmeasurethebeams,λ1andλ2measuringthereferencechannelandsamplechannelsimultaneously.Signalprocessingthencalculatesconcentrationprofilesandthestableisotoperatioisderived.

Figure1:SchematicoftheLaserIsotopeRatiometer(LIR).

Temporalmeasurements

Figure2:TemporalrecordofdeltavaluewhileswappingbetweendifferentCO2samples. Showingrapidresponseandhighsensitivity.

DeltaValue

Figure3:Allandeviationplotshowingtheprecisionoftheinstrument.