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FTIR-PHOTOACOUSTIC ... FTIR-PHOTOACOUSTIC SPECTROSCOPY 1 Niina Koivikko, Christian Hirschmann, Satu Ojala, Riitta L. Keiski Mass and Heat Transfer Process Laboratory Department of

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  • FTIR-PHOTOACOUSTIC SPECTROSCOPY

    1

    Niina Koivikko, Christian Hirschmann, Satu Ojala, Riitta L. Keiski

    Mass and Heat Transfer Process Laboratory

    Department of Process and Environmental Engineering

    University of Oulu

    POKE workshop 3

    Tallinn 11.-12.12.2013

  • INTRODUCTION TO

    PHOTOACOUSTIC SPECTROSCOPY

    • The photoacoustic effect is based on the absorption of infrared

    radiation by the sample which is heated up and the absorbed

    heat is transferred into the surrounding gas.

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    • pressure waves are

    created in the surrounding

    gas which are detected by

    a sensitive microphone

    and converted into an

    electrical signal. (Bruker)

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    INTRODUCTION TO

    PHOTOACOUSTIC SPECTRSCOPY

    • Set-up for FTIR transmission spectrometer

    • Set-up for FTIR Photoacoustic spectrometer

    Light

    source FTIR

    Sample gas

    Photoacoustic

    detector

    Gas

    cell

    For solid, semi-

    solid, liquid and

    gaseous samples

  • ADVANTAGES OF PAS OVER

    TRADITIONAL FTIR SPECTROSCOPY

    Versatile and easy sampling Suitable for different kind of samples and no sample preparation

    needed

    Zero- background method Long term stable

    Small optical path length

    Small sample volume (contactless and nonconsuming)

    Linear signal

    Capability for depth profiling

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  • FTIR VS. FTIR-PAS

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  • MEASUREMENT DEVICE IN MASS AND

    HEAT TRANSFER PROCESS LABORATORY,

    UNIVERSITY OF OULU

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    VERTEX 80V FTIR (BRUKER) PA301(GASERA)

    Uotila et al. 2010

  • BRUKER FTIR WITH PA301

    • Measures solid, semi-solid and liquid samples.

    • Hard crystalline materials or powders can be measured.

    • Hightly absorbing ”black” samples can be measured also.

    • For sample surface morphology and depth profiling

    measurements.

    • Ultra-sensitive optical microphone based on a MEMS cantilever

    sensor coupled with a laser interferometer to measure

    microscopic movement of the cantilever sensor.

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  • BRUKER FTIR WITH PA301

     Dark samples

     pharma quality control

     soil samples

     paper and wood analysis

     oil analysis

     tissue and hair samples

     polymers

     paint and pigment analysis

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  • REFERENCES

    • J. Raittila, C. Hirschmann, A. Helle, J. Tenhunen, S. Ojala, K. Rahkamaa-Tolonen R- L.

    Keiski, Measurement of Volatile Organic Compounds in Hot Emission Streams with

    Cantilever Enhanced Photoacoustic Detector, Pittcon, Orlando 12.3.2012.

    • C. Hirschmann, N. Koivikko, J. Raittila, J. Tenhunen, S. Ojala, K. Rahkamaa-Tolonen,

    R. Marbach, S. Hirschmann, R. L. Keiski (2011), FT-IR-cPAS - New Photoacoustic

    Measurement Technique for Analysis of Hot Gases: a Case Study on VOCs, Sensors 11

    (2011) 5270-2589.

    • Gasera, www.gasera.fi

    • Bruker, www.bruker.com

    • J. Uotinen, J. Raittila, I. Kauppinen, J. Kauppinen, Cantilever Enhanced Photoacoustic

    FTIR Challenges ATR and Diffuse Reflectance Techniques, Pittcon, Orlando 2010.

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  • FTIR PHOTOACOUSTIC GAS SPECTROMETER PROTOTYPE MEASUREMENTS FTIR-CPAS

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    Case study on VOCs

  • FTIR PHOTOACOUSTIC GAS SPECTROMETER PROTOTYPE MEASUREMENTS FTIR-CPAS

    • Prototype measurement device for industrial measurements.

    • The PA cell and all parts heated up to 200 degrees.

    • Case study on Volatile Organic Compounds.

    • What needs to be taken into account:

    A) VOC compounds  mixture  selectivity+ability to

    measure multicomponent gas mixtures

    B) water vapour  subtraction of water+linearity

    C) Trace concentrations  sensitivity

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    Hirschmann et al., 2011

    Acetone

    Ethanol

    Isobutanol

    Isopropanol

    Methanol

    n-butanol

    Perchloroethylene

    Methoxypropanolacete

    Methylacetate

    Methylethylketone

    o-xylene

    m-xylene

    p-xylene

    Dimethylformamide

    Dichloromethane

    Butylacetate

    Toluene

  • Christian Hirschmann

    Cantilever-enhanced photoacoustic

    spectroscopy in the analysis of volatile

    organic compounds

    Doctoral defense 14.12.2013

    (University of Oulu)

    Electronic version available at:

    http://www.vtt.fi/vtt_search.jsp?target

    =julk&form=sdef&search=%28py%3E2011+

    AND+jt=c1%29

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    http://www.vtt.fi/vtt_search.jsp?target=julk&form=sdef&search=(py>2011+AND+jt=c1) http://www.vtt.fi/vtt_search.jsp?target=julk&form=sdef&search=(py>2011+AND+jt=c1) http://www.vtt.fi/vtt_search.jsp?target=julk&form=sdef&search=(py>2011+AND+jt=c1)