umu.sePublikationer
Ändra sökning
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Methodology for fast curve fitting to modulated Voigt dispersion lineshape functions
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
2014 (Engelska)Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 133, s. 244-250Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Faraday rotation spectroscopy (FAMOS) as well as other modulated techniques that rely on dispersion produce lock-in signals that are proportional to various Fourier coefficients of modulated dispersion lineshape functions of the molecular transition targeted. In order to enable real-time curve fitting to such signals a fast methodology for calculating the Fourier coefficients of modulated lineshape functions is needed. Although there exist an analytical expression for such Fourier coefficients of modulated Lorentzian absorption and dispersion lineshape functions, there is no corresponding expression for a modulated Voigt dispersion function. The conventional computational route of such Fourier coefficients has therefore so far either consisted of using various approximations to the modulated Voigt lineshape function or solving time-consuming integrals, which has precluded accurate real-time curve fitting. Here we present a new methodology to calculate Fourier coefficients of modulated Voigt dispersion lineshape functions that is significantly faster (several orders of magnitude) and more accurate than previous approximative calculation procedures, which allows for real-time curve fitting to FAMOS signals also in the Voigt regime.

Ort, förlag, år, upplaga, sidor
Elsevier, 2014. Vol. 133, s. 244-250
Nyckelord [en]
Faraday rotation, Faraday modulation, Spectroscopy, Quantum cascade laser
Nationell ämneskategori
Atom- och molekylfysik och optik
Identifikatorer
URN: urn:nbn:se:umu:diva-68648DOI: 10.1016/j.jqsrt.2013.08.008ISI: 000328868800018OAI: oai:DiVA.org:umu-68648DiVA, id: diva2:617164
Tillgänglig från: 2013-04-22 Skapad: 2013-04-22 Senast uppdaterad: 2018-06-08Bibliografiskt granskad
Ingår i avhandling
1. Faraday modulation spectroscopy: Theoretical description and experimental realization for detection of nitric oxide
Öppna denna publikation i ny flik eller fönster >>Faraday modulation spectroscopy: Theoretical description and experimental realization for detection of nitric oxide
2013 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Faraday modulation spectroscopy (FAMOS) is a laser-based spectroscopic dispersion technique for detection of paramagnetic molecules in gas phase. This thesis presents both a new theoretical description of FAMOS and experimental results from the ultra-violet (UV) as well as the mid-infrared (MIR) regions. The theoretical description, which is given in terms of the integrated linestrength and Fourier coefficients of modulated dispersion and absorption lineshape functions, facilitates the description and the use of the technique considerably. It serves as an extension to the existing FAMOS model that thereby incorporates also the effects of lineshape asymmetries primarily originating from polarization imperfections. It is shown how the Fourier coefficients of modulated Lorentzian lineshape functions, applicable to the case with fully collisionally broadened transitions, can be expressed in terms of analytical functions. For the cases where also Doppler broadening needs to be included, resulting in lineshapes of Voigt type, the lineshape functions can be swiftly evaluated (orders of magnitude faster than previous procedures) by a newly developed method for rapid calculation of modulated Voigt lineshapes (the WWA-method). All this makes real-time curve fitting to FAMOS spectra feasible. Two experimental configurations for sensitive detection of nitric oxide (NO) by the FAMOS technique are considered and their optimum conditions are determined. The two configurations target transitions originating from the overlapping Q22(21=2) and QR12(21=2) transitions in the ultra-violet (UV) region (227nm) and the Q3=2(3=2)-transition in the fundamental rotational-vibrational band in the mid-infrared (MIR) region (5.33 µm). It is shown that the implementations of FAMOS in the UV- and MIR-region can provide detection limits in the low ppb range, which opens up the possibility for applications where high detection sensitivities of NO is required.

Ort, förlag, år, upplaga, sidor
Umeå: Umeå universitet, 2013. s. 152
Nyckelord
Faraday modulation spectroscopy (FAMOS), Westberg-Wang-Axner (WWA) method, Fourier coefficients, Lineshape asymmetries, Nitric oxide (NO)
Nationell ämneskategori
Atom- och molekylfysik och optik
Forskningsämne
fysik
Identifikatorer
urn:nbn:se:umu:diva-68649 (URN)978-91-7459-616-8 (ISBN)
Disputation
2013-05-14, Naturvetarhuset, N420, Umeå universitet, Umeå, 10:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2013-04-23 Skapad: 2013-04-22 Senast uppdaterad: 2018-06-08Bibliografiskt granskad

Open Access i DiVA

Fulltext saknas i DiVA

Övriga länkar

Förlagets fulltext

Personposter BETA

Westberg, JonasWang, JunyangAxner, Ove

Sök vidare i DiVA

Av författaren/redaktören
Westberg, JonasWang, JunyangAxner, Ove
Av organisationen
Institutionen för fysik
I samma tidskrift
Journal of Quantitative Spectroscopy and Radiative Transfer
Atom- och molekylfysik och optik

Sök vidare utanför DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetricpoäng

doi
urn-nbn
Totalt: 556 träffar
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf