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Mid-infrared pumped laser-induced thermal grating spectroscopy for detection of acetylene in the visible spectral range

Sahlberg, Anna Lena LU ; Kiefer, Johannes LU ; Aldén, Marcus LU and Li, Zhongshan LU (2016) In Applied Spectroscopy 70(6). p.1034-1043
Abstract

We present mid-infrared laser-induced thermal grating spectroscopy (IR-LITGS) using excitation radiation around 3 μm generated by a simple broadband optical parametric oscillator (OPO). Acetylene as a typical small hydrocarbon molecule is used as an example target species. A mid-infrared broadband OPO pumped by the fundamental output of a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser was used to generate the pump beams, with pulse energies of 6-10 mJ depending on the wavelength. The line width of the OPO idler beam was ∼5 cm-1, which is large enough to cover up to six adjacent acetylene lines. The probe beam was the radiation of a 532 nm cw solid state laser with 190 mW output power. Signals were generated in... (More)

We present mid-infrared laser-induced thermal grating spectroscopy (IR-LITGS) using excitation radiation around 3 μm generated by a simple broadband optical parametric oscillator (OPO). Acetylene as a typical small hydrocarbon molecule is used as an example target species. A mid-infrared broadband OPO pumped by the fundamental output of a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser was used to generate the pump beams, with pulse energies of 6-10 mJ depending on the wavelength. The line width of the OPO idler beam was ∼5 cm-1, which is large enough to cover up to six adjacent acetylene lines. The probe beam was the radiation of a 532 nm cw solid state laser with 190 mW output power. Signals were generated in atmospheric pressure gas flows of N2, air, CO2 and Ar with small admixtures of C2H2. A detection limit of less than 300 ppm was found for a point measurement of C2H2 diluted in N2. As expected, the oscillation frequency of the IR-LITGS signal was found to have a large dependency on the buffer gas, which allows determination of the speed of sound. Moreover, the results reveal a very strong collisional energy exchange between C2H2 and CO2 compared to the other gases. This manifests as significant local heating. In summary, the MIR-LITGS technique enables spectroscopy of fundamental vibrational transitions in the infrared via detection in the visible spectral range.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
acetylene, Hydrocarbon detection, laser-induced gratings, LITGS, nonlinear optical spectroscopy, quenching
in
Applied Spectroscopy
volume
70
issue
6
pages
10 pages
publisher
Society for Applied Spectroscopy
external identifiers
  • scopus:84973279542
  • wos:000378411500010
ISSN
0003-7028
DOI
10.1177/0003702816641271
language
English
LU publication?
yes
id
82c7cbac-cf87-4d11-9683-ddf8573d7ed3
date added to LUP
2017-01-26 10:22:04
date last changed
2017-11-19 04:37:05
@article{82c7cbac-cf87-4d11-9683-ddf8573d7ed3,
  abstract     = {<p>We present mid-infrared laser-induced thermal grating spectroscopy (IR-LITGS) using excitation radiation around 3 μm generated by a simple broadband optical parametric oscillator (OPO). Acetylene as a typical small hydrocarbon molecule is used as an example target species. A mid-infrared broadband OPO pumped by the fundamental output of a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser was used to generate the pump beams, with pulse energies of 6-10 mJ depending on the wavelength. The line width of the OPO idler beam was ∼5 cm<sup>-1</sup>, which is large enough to cover up to six adjacent acetylene lines. The probe beam was the radiation of a 532 nm cw solid state laser with 190 mW output power. Signals were generated in atmospheric pressure gas flows of N<sub>2</sub>, air, CO<sub>2</sub> and Ar with small admixtures of C<sub>2</sub>H<sub>2</sub>. A detection limit of less than 300 ppm was found for a point measurement of C<sub>2</sub>H<sub>2</sub> diluted in N<sub>2</sub>. As expected, the oscillation frequency of the IR-LITGS signal was found to have a large dependency on the buffer gas, which allows determination of the speed of sound. Moreover, the results reveal a very strong collisional energy exchange between C<sub>2</sub>H<sub>2</sub> and CO<sub>2</sub> compared to the other gases. This manifests as significant local heating. In summary, the MIR-LITGS technique enables spectroscopy of fundamental vibrational transitions in the infrared via detection in the visible spectral range.</p>},
  author       = {Sahlberg, Anna Lena and Kiefer, Johannes and Aldén, Marcus and Li, Zhongshan},
  issn         = {0003-7028},
  keyword      = {acetylene,Hydrocarbon detection,laser-induced gratings,LITGS,nonlinear optical spectroscopy,quenching},
  language     = {eng},
  month        = {06},
  number       = {6},
  pages        = {1034--1043},
  publisher    = {Society for Applied Spectroscopy},
  series       = {Applied Spectroscopy},
  title        = {Mid-infrared pumped laser-induced thermal grating spectroscopy for detection of acetylene in the visible spectral range},
  url          = {http://dx.doi.org/10.1177/0003702816641271},
  volume       = {70},
  year         = {2016},
}