umu.sePublications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Mid- and near-infrared NICE-OHMS: techniques for ultra-sensitive detection of molecules in gas phase
Umeå University, Faculty of Science and Technology, Department of Physics.
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS) is a technique for ultra-sensitive detection of molecular absorption and dispersion. For highest performance, the technique combines cavity enhancement (CE) with frequency modulation (FM); while the former increases the effective interaction length between the light and the analyte by several orders of magnitudes, the latter removes the in-coupling of 1/f noise and makes the signals background free. The combination of CE and FM also gives the technique an immunity to amplitude noise caused by the jitter of the laser frequency relative to the cavity resonance frequencies. All these properties make the technique suitable for ultra sensitive trace gas detection in the sub-parts-per-trillion (ppt) range. The aim of this thesis is to improve the performance of the NICE-OHMS technique and to increase its range of applications.

The work in this thesis can be divided into three areas:Firstly, a mid-infrared (MIR)-NICE-OHMS instrumentation was developed. In a first realization an unprecedented white-noise equivalent absorption limit for Doppler broadened (Db) detection in the MIR of 3×10-9 cm-1Hz-1/2was demonstrated. This was subsequently improved to 2.4×10-10 cm-1Hz-1/2allowing for detection methane and its two main isotopologues (CH3D and 13CH4) at their natural abundance.Secondly, further development of an existing near-infrared NICE-OHMS system was performed. This resulted in an improved longtime stability and the first shot-noise limited NICE-OHMS system for Db detection with a noise equivalent absorption limit of 2.3×10-14 cm-1detected over 200 s. Thirdly, models and theoretical descriptions of NICE-OHMS signals under strong absorption conditions and from methane under high laser power were developed. It was experimentally verified that the models allow for a more accurate evaluation of NICE-OHMS signals under a wide range of conditions.

Abstract [sv]

Brusimmun kavitetsförstärkt optisk-heterodyndetekterad molekylärspektroskopi (eng.Noise-immune cavity-enhanced optical heterodyne molecular spectrometry, NICE-OHMS) är en teknik för ultrakänslig detektion av molekylär absorption och dispersion. NICE-OHMS-tekniken kombinerar kavitetsförstärkning (eng. CE) med frekvensmodulering (FM); emedan den första väsentligt ökar den effektiva interaktionslängden mellan ljuset och analyten vilket ökar teknikens känslighet, tar den senare bort inkopplingen av 1/f-brus och gör signalerna bakgrundsfria. Kombinationen av CE och FM ger också tekniken en immunitet mot amplitudstörning som orsakas av jitter hos laserljusets frekvens i förhållande till kavitetsresonansfrekvenserna. Alla dessa egenskaper gör tekniken lämplig för ultrakänslig spårgasdetektering i och under ppt (eng. parts-per-trillion) - området. Syftet med denna avhandling är att förbättra prestandan hos NICE-OHMS-tekniken och att öka dess tillämpningspotential.

Avhandlingen kan delas in i tre delar: Inom den första utvecklades en mid-infraröd (MIR)-NICE-OHMS instrumentering. Vid en första realisering påvisades en aldrig tidigare uppnådd vitt-brus-ekvivalent absorptionsgräns för Dopplerbreddad (Db) detektering i MIR området på 3 × 10-9 cm-1Hz-1/2. Detta förbättrades därefter till 2,4 x 10-10 cm-1Hz-1/2, vilket möjliggör detektering av metan och dess två huvudsakliga isotopologer (CH3D och 13CH4) vid deras naturliga förekomst. Inom det andra området utfördes vidareutveckling av ett existerande NICE-OHMS-system verksamt i det när-infraröda (NIR) området. Detta resulterade i en förbättrad långtidsstabilitet och en brus-ekvivalent absorptionsgräns för Db detektion på 2,3 × 10-14 cm-1 mätt över 200 s. Inom den tredje utvecklades modeller och teoretiska beskrivningar av NICE-OHMS under starka absorptionsförhållanden och från metan under hög laserintensitet. Det var experimentellt verifierat att modellerna möjliggör en mer noggrann utvärdering av NICE-OHMS-signalerunder ett stort antal förhållanden.

Place, publisher, year, edition, pages
Umeå: Umeå universitet , 2018. , p. 139
Keywords [en]
spectrometry, NICE-OHMS, trace gas detection, acetylene, methane, isotopologues, near-infrared, mid-infrared, shot-noise, optical parametric oscillator
National Category
Atom and Molecular Physics and Optics
Research subject
Technical Physics
Identifiers
URN: urn:nbn:se:umu:diva-153068ISBN: 978-91-7601-977-1 (print)OAI: oai:DiVA.org:umu-153068DiVA, id: diva2:1261046
Public defence
2018-11-30, N450, Naturvetarhuset, Umeå, 10:00 (English)
Opponent
Supervisors
Available from: 2018-11-09 Created: 2018-11-06 Last updated: 2018-11-13Bibliographically approved
List of papers
1. Doppler-broadened mid-infrared noise-immune cavity-enhanced optical heterodyne molecular spectrometry based on an optical parametric oscillator for trace gas detection
Open this publication in new window or tab >>Doppler-broadened mid-infrared noise-immune cavity-enhanced optical heterodyne molecular spectrometry based on an optical parametric oscillator for trace gas detection
Show others...
2015 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 40, no 4, p. 439-442Article in journal (Refereed) Published
Abstract [en]

An optical parametric oscillator based Doppler-broadened (Db) noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS) system suitable for addressing fundamental vibrational transitions in the 3.2-3.9 mu m mid-infrared (MIR) region has been realized. An Allan-Werle analysis provides a detection sensitivity of methane of 1.5 x 10-9 cm(-1) with a 20 s integration time, which corresponds to 90 ppt of CH4 if detected at the strongest transition addressed at 40 Torr. This supersedes that of previous Db MIR NICE-OHMS demonstrations and suggests that the technique can be suitable for detection of both the environmentally important (CH4)-C-13 and CH3D isotopologues. It also opens up for detection of many other molecular species at ppt and sub-ppt concentration levels.

National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-101400 (URN)10.1364/OL.40.000439 (DOI)000349848400001 ()25680119 (PubMedID)
Available from: 2015-07-02 Created: 2015-03-30 Last updated: 2018-11-06Bibliographically approved
2. Narrowing of the linewidth of an optical parametric oscillator by an acousto-optic modulator for the realization of mid-IR noise-immune cavity-enhanced optical heterodyne molecular spectrometry down to 10(-10) cm(-1) Hz(-1/2)
Open this publication in new window or tab >>Narrowing of the linewidth of an optical parametric oscillator by an acousto-optic modulator for the realization of mid-IR noise-immune cavity-enhanced optical heterodyne molecular spectrometry down to 10(-10) cm(-1) Hz(-1/2)
2015 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 23, no 26, p. 33641-33655, article id UNSP 252446Article in journal (Refereed) Published
Abstract [en]

The linewidth of a singly resonant optical parametric oscillator (OPO) has been narrowed with respect to an external cavity by the use of an acousto-optic modulator (AOM). This made possible an improvement of the sensitivity of a previously realized OPO-based noise-immune cavity-enhanced optical heterodyne molecular spectrometry instrument for the 3.2 - 3.9 mu m mid-infrared region by one order of magnitude. The resulting system shows a detection sensitivity for methane of 2.4 x 10(-10) cm(-1) Hz(-1/2) and 1.3 x 10(-10) cm(-1) at 20 s, which allows for detection of both the environmentally important (CH4)-C-13 and CH3D isotopologues in atmospheric samples. (C) 2015 Optical Society of America

Keywords
VOE RG, 1984, PHYSICAL REVIEW A, V30, P2827 ittaker K. E., 2012, APPLIED PHYSICS B-LASERS AND OPTICS, V109, P333 Cartt A. D., 2015, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM
National Category
Physical Sciences
Identifiers
urn:nbn:se:umu:diva-116097 (URN)10.1364/OE.23.033641 (DOI)000368004600074 ()
Available from: 2016-02-08 Created: 2016-02-08 Last updated: 2018-11-06Bibliographically approved
3. Doppler-broadened mid-infrared NICE-OHMS system based on an optical parametric oscillator
Open this publication in new window or tab >>Doppler-broadened mid-infrared NICE-OHMS system based on an optical parametric oscillator
2016 (English)In: Laser Applications to Chemical, Security and Environmental Analysis, 2016Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

An OPO-based NICE-OHMS instrument for trace gas detection addressing fundamental vibration transitions in the mid-IR (3.2-3.9 µm) range has been developed. It shows a detection sensitivity for CH4 of 2.4×10−10cm−1Hz−1∕2 (corresponding to low ppt concentrations).

National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-153067 (URN)10.1364/LACSEA.2016.LT2G.2 (DOI)978-1-943580-15-6 (ISBN)
Conference
Imaging and Applied Optics 2016, 25–28 July 2016, Heidelberg, Germany
Available from: 2018-11-06 Created: 2018-11-06 Last updated: 2018-11-06Bibliographically approved
4. Doppler-broadened NICE-OHMS beyond the cavity-limited weak absorption condition – I. Theoretical Description
Open this publication in new window or tab >>Doppler-broadened NICE-OHMS beyond the cavity-limited weak absorption condition – I. Theoretical Description
2016 (English)In: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 168, p. 217-244Article in journal (Other academic) Published
Abstract [en]

Doppler-broadened (Db) noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS) is conventionally described by an expression (here referred to as the CONV expression) that is restricted to the case when the single-pass absorbance, α0L, is much smaller than the empty cavity losses, π/F [here termed the conventional cavity-limited weak absorption (CCLWA) condition]. This limits the applicability of the technique, primarily its dynamic range and calibration capability. To remedy this, this work derives extended descriptions of Db NICEOHMS that are not restricted to the CCLWA condition. First, the general principles of Db NICEOHMS are scrutinized in some detail. Based solely upon a set of general assumptions, predominantly that it is appropriate to linearize the Beer–Lambert law, that the light is modulated to a triplet, and that the Pound–Drever–Hall sidebands are fully reflected, a general description of Db NICE-OHMS that is not limited to any specific restriction on α0L vs. π/F, here referred to as the FULL description, is derived. However, this description constitutes a set of equations to which no closed form solution has been found. Hence, it needs to be solved numerically (by iterations), which is inconvenient. To circumvent this, for the cases when α0Loπ/F but without the requirement that the stronger CCLWA condition needs to be fulfilled, a couple of simplified extended expressions that are expressible in closed analytical form, referred to as the extended locking and extended transmission description, ELET, and the extended locking and full transmission description, ELFT, have been derived. An analysis based on simulations validates the various descriptions and assesses to which extent they agree. It is shown that in the CCLWA limit, all extended descriptions revert to the CONV expression. The latter one deviates though from the extended ones for α0L around and above 0.1π/F. The two simplified extended descriptions agree with the FULL description for a larger range of α0L than the CONV expression, viz. for the ELET description for α0L up to 0.3π/F and for ELFT for α0L up to 0.6 or 1.0 π/F (depending on the mode of detection). It is then demonstrated that the conventional view of Db NICE-OHMS, which states that the out-of-phase and the in-phase signals can be referred to as a pure absorption and dispersion signal, respectively, breaks down when the CCLWA condition does not hold. In this case, the out-of-phase signal is additionally affected by the phase shifts of the laser components (i.e. dispersion) while the in-phase signal is also influenced by their attenuation. Access to new descriptions broadens considerably the dynamic range of Db NICE-OHMS and facilitates calibration using standard references samples, and thereby its applicability

Keywords
NICE-OHMS, Cavity enhanced spectroscopy, Dynamic range, Frequency modulation spectroscopy, Theoretical model
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-110271 (URN)10.1016/j.jqsrt.2015.09.007 (DOI)000366007000018 ()
Available from: 2015-10-19 Created: 2015-10-19 Last updated: 2018-11-06Bibliographically approved
5. Doppler-broadened NICE-OHMS beyond the cavity-limited weak absorption condition – II: experimental verification
Open this publication in new window or tab >>Doppler-broadened NICE-OHMS beyond the cavity-limited weak absorption condition – II: experimental verification
2016 (English)In: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 168, p. 245-256Article in journal (Refereed) Published
Abstract [en]

Doppler-broadened (Db) noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS) is normally described by an expression, here termed the conventional (CONV) description, that is restricted to the conventional cavity-limited weak absorption condition (CCLWA), i.e. when the single pass absorbance is significantly smaller than the empty cavity losses, i.e. when α0L<<π/F. To describe NICE-OHMS signals beyond this limit two simplified extended descriptions (termed the extended locking and extended transmission description, ELET, and the extended locking and full transmission description, ELFT), which are assumed to be valid under the relaxed cavity-limited weak absorption condition (RCLWA), i.e. when α0L<π/Fα0L<π/F, and a full description (denoted FULL), presumed to be valid also when the α0L<π/Fα0L<π/F condition does not hold, have recently been derived in an accompanying work (Ma W, et al. Doppler-broadened NICE-OHMS beyond the cavity-limited weak absorption condition - I. Theoretical Description. J Quant Spectrosc Radiat Transfer, 2015, http://dx.doi.org/10.1016/j.jqsrt.2015.09.007, this issue). The present work constitutes an experimental verification and assessment of the validity of these, performed in the Doppler limit for a set of Fα0L/πFα0L/π values (up to 3.5); it is shown under which conditions the various descriptions are valid. It is concluded that for samples with Fα0L/πFα0L/π up to 0.01, all descriptions replicate the data well. It is shown that the CONV description is adequate and provides accurate assessments of the signal strength (and thereby the analyte concentration) up to Fα0L/πFα0L/π of around 0.1, while the ELET is accurate for Fα0L/πFα0L/π up to around 0.3. The ELFT description mimics the Db NICE-OHMS signal well for Fα0L/πFα0L/π up to around unity, while the FULL description is adequate for all Fα0L/πFα0L/π values investigated. Access to these descriptions both increases considerably the dynamic range of the technique and facilitates calibration using certified reference gases, which thereby significantly broadens the applicability of the Db NICE-OHMS technique.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
NICE OHMS, Frequency modulation spectroscopy, Cavity enhanced spect, Experimental verification
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-110273 (URN)10.1016/j.jqsrt.2015.09.008 (DOI)000366007000019 ()
Available from: 2015-10-19 Created: 2015-10-19 Last updated: 2018-11-06Bibliographically approved
6. Whispering-gallery-mode laser-based noise-immune cavity-enhanced optical heterodyne molecular spectrometry
Open this publication in new window or tab >>Whispering-gallery-mode laser-based noise-immune cavity-enhanced optical heterodyne molecular spectrometry
2017 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 42, no 16, p. 3109-3112Article in journal (Refereed) Published
Abstract [en]

The whispering-gallery-mode (WGM) laser is a type of laser that has an exceptionally narrow linewidth. Noise-immune cavity-enhanced optical heterodyne molecular spectrometry, which is a detection technique with extraordinary properties that benefit from narrow linewidth lasers, has been realized with a WGM laser. By locking to a cavity with a finesse of 55 000, acetylene and carbon dioxide could be simultaneously detected down to an unprecedented noise equivalent absorption per unit length of 6.6 x 10(-14) cm(-1) over 150 s, corresponding to 5 ppt of C2H2.

Place, publisher, year, edition, pages
OPTICAL SOC AMER, 2017
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-142879 (URN)10.1364/OL.42.003109 (DOI)000407640000014 ()28809884 (PubMedID)
Available from: 2017-12-13 Created: 2017-12-13 Last updated: 2018-11-06Bibliographically approved
7. Differential noise-immune cavity-enhanced optical heterodyne molecular spectroscopy for improvement of the detection sensitivity by reduction of drifts from background signals
Open this publication in new window or tab >>Differential noise-immune cavity-enhanced optical heterodyne molecular spectroscopy for improvement of the detection sensitivity by reduction of drifts from background signals
2017 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 25, no 23, p. 29454-29471Article in journal (Refereed) Published
Abstract [en]

The detection sensitivity of noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) is often limited by background signals that bring in drifts. A novel realization of NICE-OHMS, termed differential NICE-OHMS, that both reduces such drifts and enlarges the molecular signal is presented. It is based on simultaneous detection of NICE-OHMS signals in reflection and transmission, followed by a subtraction of the former (properly weighted) from the latter. An Allan plot analysis shows that the instrumentation could demonstrate a noise equivalent absorption per unit length (NEAL) of 4.7 × 10−14 cm−1, obtained for an integration time of 170 s.

Place, publisher, year, edition, pages
Optical Society of America, 2017
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-142459 (URN)10.1364/OE.25.029454 (DOI)000415136700127 ()
Available from: 2017-12-04 Created: 2017-12-04 Last updated: 2018-11-06Bibliographically approved
8. Shot-noise-limited Doppler-broadened noise-immune cavity-enhanced optical heterodyne molecular spectrometry
Open this publication in new window or tab >>Shot-noise-limited Doppler-broadened noise-immune cavity-enhanced optical heterodyne molecular spectrometry
2018 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 43, no 4, p. 715-718Article in journal (Refereed) Published
Abstract [en]

Shot-noise-limited Doppler-broadened (Db) noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS) has been realized by implementation of balanced detection. A characterization of the system based on Allan-Werle plots of the absorption coefficient, retrieved by fitting a model function to data, shows that the system has a white noise equivalent absorption per unit length per square root of bandwidth of 2.3 x 10(-13) cm(-1) Hz(-1/2), solely 44% above the shot noise limit, and a detection sensitivity of 2.2 x 10(-14) cm(-1) over 200 s, both being unprecedented for Db NICE-OHMS. The white noise response follows the expected inverse square root dependence on power that is representative of a shot-noise-limited response, which confirms that the system is shot-noise-limited. 

National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-145590 (URN)10.1364/OL.43.000715 (DOI)000425123700023 ()29444060 (PubMedID)
Funder
Swedish Research Council, 2015-04374
Available from: 2018-03-21 Created: 2018-03-21 Last updated: 2018-11-06Bibliographically approved
9. Depletion of the vibrational ground state of CH4 in absorption spectroscopy at 3.4 μm in N2 and air in the 1-100Torr range
Open this publication in new window or tab >>Depletion of the vibrational ground state of CH4 in absorption spectroscopy at 3.4 μm in N2 and air in the 1-100Torr range
2018 (English)In: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 205, p. 59-70Article in journal (Refereed) Published
Abstract [en]

A model presented in an accompanying work predicts that mid-IR absorption signals from methane in trace concentrations in various buffer gases detected at pressures in the 1-100Torr range can be reduced and distorted due to depletion of the vibrational ground state if the molecules are exposed to laser powers in the tens of mW range or above. This work provides experimental evidence of such depletion in a resonant cavity under a variety of conditions, e.g. for intracavity laser powers up to 2W and for buffer gases of N-2 or dry air, and verifies the applicability of the model. It was found that the degree of depletion is significantly larger in N-2 than dry air, and that it increases with pressure for pressures up to around 10Torr (attributed to a decreased diffusion rate) but decreases with pressure for pressures above 20Torr (caused by an increased collisional vibrational decay rate). The maximum degree of depletion (similar to 80%) was obtained for methane in N-2 at around 15Torr. This implies that absorption spectrometry of methane can experience significant non-linear dependencies on laser power, pressure, as well as buffer gas composition. It is shown that depletion takes place also in (CH4)-C-13, which verifies the applicability of the model also for this isotopologue, and that NICE-OHMS signals detected in absorption phase are less affected by depletion than in dispersion. It was concluded that the absorption mode of detection can provide concentration assessments that are virtually free of influence of depletion for intracavity powers below 0.8 W. 

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2018
Keywords
Absorption spectroscopy, Cavity enhanced, Noise-immune cavity-enhanced optical heterodyne molecular spectroscopy, Methane, Depletion, Optical saturation
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-143714 (URN)10.1016/j.jqsrt.2017.10.007 (DOI)000417665000008 ()
Available from: 2018-01-08 Created: 2018-01-08 Last updated: 2018-11-06Bibliographically approved
10. Model for molecular absorption spectroscopy in the 1-100 Torr range in the presence of vibrational depletion - Applied to CH4 in N2 and dry air
Open this publication in new window or tab >>Model for molecular absorption spectroscopy in the 1-100 Torr range in the presence of vibrational depletion - Applied to CH4 in N2 and dry air
(English)Manuscript (preprint) (Other academic)
Abstract [en]

When molecules whose collision induced vibrational decay rates are small are probed by molecular absorption spectroscopic (MAS) techniques the absorption signal can, under certain conditions, be reduced and distorted. The reason has been attributed to the fact that a substantial fraction of the molecules in the interaction region will reside in excited vibrational states, which leads to a depletion of the vibrational ground state. One type of molecule in which this can take place is methane. A model for this phenomenon, based on CH4 in trace concentrations in either N2 or dry air in a cylindrical gas cell, detected by mid-infrared light in the 1 - 100 Torr pressure range, is presented. Due to a fast collisional coupling between various rotational states and velocity groups we suggest that depletion in MAS can be modeled adequately by a simple three-level system to which the transport of molecules in the system is coupled as diffusion according to Fick's law, applied to each level individually. The model is verified in a separate work [Hausmaninger T et al., J Quant Spectrosc Radiat Tr. 2017;205:59-70] with good agreement. It predicts that depletion has a strong pressure dependence in the 1 - 30 Torr range, that it is significantly more pronounced in N2 than in air, and that considerable degrees of depletion can be obtained for mW powers of light (> 10% for powers > 20 mW). The findings indicate that, unless precautions are taken, depletion can adversely affect quantitative assessments performed by MAS. Means of how to reduce depletion are given.

National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
urn:nbn:se:umu:diva-153063 (URN)
Available from: 2018-11-06 Created: 2018-11-06 Last updated: 2018-11-07
11. High resolution ultra-sensitive trace gas detection by use of cavity-position-modulated sub-Doppler NICE-OHMS - Application to detection of acetylene in human breath
Open this publication in new window or tab >>High resolution ultra-sensitive trace gas detection by use of cavity-position-modulated sub-Doppler NICE-OHMS - Application to detection of acetylene in human breath
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [en]

A sensitive high resolution spectrometer for trace gas detection of species whose transitions have severe spectral overlap with abundant concomitant species by sub-Doppler (sD) noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS) is presented. The setup is based on a NICE-OHMS instrumentation utilizing balanced detection that provides shot-noise limited Doppler-broadened (Db) detection. An additional layer of modulation is added to reduce the influence of narrow etalons and improve the sensitivity for sD detection. By dithering synchronously the positions of the two cavity mirrors, the effect of residual etalons between one of the cavity mirrors and another surface in the system could be reduced without affecting the frequencies of the cavity mode. This reduced the drifts in the system, allowing for an Allan deviation of the absorption coefficient of 2.2×10−13 cm−1 for an integration time of 60 s, which, for the targeted C2H2 transition at 6518.4858 cm−1, corresponds to a 3σ detection sensitivity of 130 ppt. Sub-Doppler trace gas detection is demonstrated by measuring ppb levels of C2H2 in the exhaled breath of smokers. A procedure was worked out for simultaneous detection of CO2, based on the Db response. It is shown that despite significant spectral interference from CO2, which precludes Db detection of C2H2 in breath, acetylene could be detected in breath from smokers with good spectral resolution by the use of sD NICE-OHMS.

National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-153065 (URN)
Available from: 2018-11-06 Created: 2018-11-06 Last updated: 2018-11-07

Open Access in DiVA

fulltext(4628 kB)70 downloads
File information
File name FULLTEXT01.pdfFile size 4628 kBChecksum SHA-512
bb3f2e8471295dd73bd6cb5f4002ac9cb182508e3df8dc89a494b7f66d7f904b49ca410079ff7fa5bd8c038c5829e322163d9b1181e0459f842ff154cc0b05c8
Type fulltextMimetype application/pdf
spikblad(185 kB)7 downloads
File information
File name SPIKBLAD01.pdfFile size 185 kBChecksum SHA-512
0a68e7de2f863b7a0a872d56ceb4a29f424067c5a8e59d865a1f4c1e53703afd3c85e88992dcf6c3d0a15763427ef1ac8eec24471c57ee94f56c8b9ba1690488
Type spikbladMimetype application/pdf
cover(34 kB)0 downloads
File information
File name COVER01.pngFile size 34 kBChecksum SHA-512
52489e0c8042b720b549c211e97cb1e02b8478a81d4c796b0b1963d1be093bd68c72d02f9c2ac08898f439ac7839b529ac917749a37b6d239633951644719e0e
Type coverMimetype image/png

Authority records BETA

Hausmaninger, Thomas

Search in DiVA

By author/editor
Hausmaninger, Thomas
By organisation
Department of Physics
Atom and Molecular Physics and Optics

Search outside of DiVA

GoogleGoogle Scholar
Total: 70 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 479 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf