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Romadanov I, Raitses Y, Smolyakov A. Wavelength modulation laser-induced fluorescence for plasma characterization. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2024; 95:073516. [PMID: 39012181 DOI: 10.1063/5.0187687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 06/24/2024] [Indexed: 07/17/2024]
Abstract
Laser-Induced Fluorescence (LIF) spectroscopy is an essential tool for probing ion and atom velocity distribution functions (VDFs) in complex plasmas. VDFs carry information about the kinetic properties of species that is critical for plasma characterization. Accurate interpretation of these functions is challenging due to factors such as multicomponent distributions, broadening effects, and background emissions. Our research investigates the use of Wavelength Modulation (WM) LIF to enhance the sensitivity of VDF measurements. Unlike standard Amplitude Modulation (AM) methods, WM-LIF measures the derivative of the LIF signal. This approach makes variations in VDF shape more pronounced. VDF measurements with WM-LIF were investigated with both numerical modeling and experimental measurements. The developed model enables the generation of both WM and AM signals, facilitating comparative analysis of fitting outcomes. Experiments were conducted in a weakly collisional argon plasma with magnetized electrons and non-magnetized ions. Measurements of the argon ion VDFs employed a narrow-band tunable diode laser, which scanned the 4p4D7/2-3d4F9/2 transition centered at 664.553 nm in vacuum. A lock-in amplifier detected the second harmonic WM signal, which was generated by modulating the laser wavelength with an externally controlled piezo-driven mirror of the diode laser. Our findings indicate that the WM-LIF signal is more sensitive to fitting parameters, allowing for better identification of VDF parameters such as the number of distribution components, their temperatures, and velocities. In addition, WM-LIF can serve as an independent method to verify AM measurements and is particularly beneficial in environments with substantial light noise or background emissions, such as those involving thermionic cathodes and reflective surfaces.
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Affiliation(s)
- I Romadanov
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - Y Raitses
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - A Smolyakov
- Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
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Zhao G, Tan W, Jia M, Hou J, Ma W, Dong L, Zhang L, Feng X, Wu X, Yin W, Xiao L, Axner O, Jia S. Intensity-Stabilized Fast-Scanned Direct Absorption Spectroscopy Instrumentation Based on a Distributed Feedback Laser with Detection Sensitivity down to 4 × 10 -6. SENSORS (BASEL, SWITZERLAND) 2016; 16:E1544. [PMID: 27657082 PMCID: PMC5038816 DOI: 10.3390/s16091544] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 09/14/2016] [Accepted: 09/14/2016] [Indexed: 12/02/2022]
Abstract
A novel, intensity-stabilized, fast-scanned, direct absorption spectroscopy (IS-FS-DAS) instrumentation, based on a distributed feedback (DFB) diode laser, is developed. A fiber-coupled polarization rotator and a fiber-coupled polarizer are used to stabilize the intensity of the laser, which significantly reduces its relative intensity noise (RIN). The influence of white noise is reduced by fast scanning over the spectral feature (at 1 kHz), followed by averaging. By combining these two noise-reducing techniques, it is demonstrated that direct absorption spectroscopy (DAS) can be swiftly performed down to a limit of detection (LOD) (1σ) of 4 × 10-6, which opens up a number of new applications.
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Affiliation(s)
- Gang Zhao
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China; (G.Z.); (W.T.); (M.J.); (J.H.); (L.D.); (L.Z.); (W.Y.); (L.X.); (S.J.)
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Wei Tan
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China; (G.Z.); (W.T.); (M.J.); (J.H.); (L.D.); (L.Z.); (W.Y.); (L.X.); (S.J.)
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Mengyuan Jia
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China; (G.Z.); (W.T.); (M.J.); (J.H.); (L.D.); (L.Z.); (W.Y.); (L.X.); (S.J.)
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Jiajuan Hou
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China; (G.Z.); (W.T.); (M.J.); (J.H.); (L.D.); (L.Z.); (W.Y.); (L.X.); (S.J.)
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Weiguang Ma
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China; (G.Z.); (W.T.); (M.J.); (J.H.); (L.D.); (L.Z.); (W.Y.); (L.X.); (S.J.)
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
- Department of Physics, Umeå University, Umeå SE-901 87, Sweden;
| | - Lei Dong
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China; (G.Z.); (W.T.); (M.J.); (J.H.); (L.D.); (L.Z.); (W.Y.); (L.X.); (S.J.)
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Lei Zhang
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China; (G.Z.); (W.T.); (M.J.); (J.H.); (L.D.); (L.Z.); (W.Y.); (L.X.); (S.J.)
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Xiaoxia Feng
- Department of Electrical Engineering and Automation, Shanxi Polytechnic College, Taiyuan 030006, China;
| | - Xuechun Wu
- Shanxi Guohui Optoelectronic Technology CO., Ltd., Taiyuan 030006, China;
| | - Wangbao Yin
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China; (G.Z.); (W.T.); (M.J.); (J.H.); (L.D.); (L.Z.); (W.Y.); (L.X.); (S.J.)
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Liantuan Xiao
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China; (G.Z.); (W.T.); (M.J.); (J.H.); (L.D.); (L.Z.); (W.Y.); (L.X.); (S.J.)
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Ove Axner
- Department of Physics, Umeå University, Umeå SE-901 87, Sweden;
| | - Suotang Jia
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China; (G.Z.); (W.T.); (M.J.); (J.H.); (L.D.); (L.Z.); (W.Y.); (L.X.); (S.J.)
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
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Abstract
Abstract
We highlight the capabilities and potential of diode laser induced fluorescence for measurements in gas-phase reacting flows. Many applications of diode lasers in practical sensing are based on absorption spectroscopy. Fluorescence-based diagnostics possess similar advantages in terms of practicality and implementation-cost but additionally are capable of achieving excellent spatial resolution. Diode laser fluorescence instruments have been employed for high-sensitivity trace gas monitoring in applications ranging from plasma physics to atmospheric chemistry. This article begins by describing the UV-visible diode laser technology used to perform fluorescence. The principles of diode laser induced fluorescence are then reviewed and a comparison is made with absorption spectroscopy. Examples are given of concentration measurements of both atomic and molecular trace gases. Recent work on using diode laser induced atomic fluorescence for precision measurements of flame temperature is also reviewed. We conclude by a discussion of future opportunities for diode laser fluorescence spectroscopy drawing attention to interesting potential target species as well as novel application areas, such as monitoring of synthesis processes for nanomaterials.
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Affiliation(s)
| | - Clemens F. Kaminski
- University of Cambridge, Department of Chemical Engineering, Cambridge, Großbritannien
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Schorsch S, Kiefer J, Leipertz A, Li Z, Aldén M. Detection of flame radicals using light-emitting diodes. APPLIED SPECTROSCOPY 2010; 64:1330-1334. [PMID: 21144149 DOI: 10.1366/000370210793561538] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Lasers are common tools in the field of combustion diagnostics. In some respects, however, they have disadvantages. Therefore, there is a need for new light sources delivering radiation in the required wavelength regions with high stability and reliability at low cost. Light-emitting diodes (LED) in the near- and mid-infrared spectral region have proven their potential for spectroscopic applications in the past. In the present work we demonstrate the feasibility of using ultraviolet LEDs for flame diagnostics. For this purpose, OH and CH radicals are detected in premixed methane/air flames. The LED emission is found to be stable after thermal equilibrium is reached. This was the case after a warming-up period in the order of minutes. The spectral characteristics were stable during a 24-h test.
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Affiliation(s)
- Stefan Schorsch
- Lehrstuhl für Technische Thermodynamik and Erlangen Graduate School in Advanced Optical Technologies (SAOT), Universität Erlangen-Nürnberg, Germany
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Vasudevan V, Hanson RK, Golden DM, Bowman CT, Davidson DF. High-Temperature Shock Tube Measurements of Methyl Radical Decomposition. J Phys Chem A 2007; 111:4062-72. [PMID: 17388279 DOI: 10.1021/jp0677187] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have studied the two-channel thermal decomposition of methyl radicals in argon, involving the reactions CH3 + Ar --> CH + H2 + Ar (1a) and CH3 + Ar --> CH2 + H + Ar (1b), in shock tube experiments over the 2253-3527 K temperature range, at pressures between 0.7 and 4.2 atm. CH was monitored by continuous-wave, narrow-line-width laser absorption at 431.1311 nm. The collision-broadening coefficient for CH in argon, 2gamma(CH-Ar), was measured via repeated single-frequency experiments in the ethane pyrolysis system behind reflected shock waves. The measured 2gamma(CH-Ar) value and updated spectroscopic and molecular parameters were used to calculate the CH absorption coefficient at 431.1311 nm (23194.80 cm(-1)), which was then used to convert raw traces of fractional transmission to quantitative CH concentration time histories in the methyl decomposition experiments. The rate coefficient of reaction 1a was measured by monitoring CH radicals generated upon shock-heating highly dilute mixtures of ethane, C2H6, or methyl iodide, CH3I, in an argon bath. A detailed chemical kinetic mechanism was used to model the measured CH time histories. Within experimental uncertainty and scatter, no pressure dependence could be discerned in the rate coefficient of reaction 1a in the 0.7-4.2 atm pressure range. A least-squares, two-parameter fit of the current measurements, applicable between 2706 and 3527 K, gives k(1a) (cm(3) mol(-1) s(-1)) = 3.09 x 1015 exp[-40700/T (K)]. The rate coefficient of reaction 1b was determined by shock-heating dilute mixtures of C2H6 or CH3I and excess O2 in argon. During the course of reaction, OH radicals were monitored using the well-characterized R(1)(5) line of the OH A-X (0,0) band at 306.6871 nm (32606.52 cm(-1)). H atoms generated via reaction 1b rapidly react with O2, which is present in excess, forming OH. The OH traces are primarily sensitive to reaction 1b, reaction 9 (H + O2 --> OH + O) and reaction 10 (CH3 + O2 --> products), where the rate coefficients of reactions 9 and 10 are relatively well-established. No pressure dependence could be discerned for reaction 1b between 1.1 and 3.9 atm. A two-parameter, least-squares fit of the current data, valid over the 2253-2975 K temperature range, yields the rate expression k(1b) (cm(3) mol(-1) s(-1)) = 2.24 x 10(15) exp[-41600/T (K)]. Theoretical calculations carried out using a master equation/RRKM analysis fit the measurements reasonably well.
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Affiliation(s)
- Venkatesh Vasudevan
- High Temperature Gasdynamics Laboratory, Mechanical Engineering Department, Stanford University, Stanford, California 94305, USA.
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Anderson TN, Lucht RP, Barron-Jimenez R, Hanna SF, Caton JA, Walther T, Roy S, Brown MS, Gord JR, Critchley I, Flamand L. Combustion exhaust measurements of nitric oxide with an ultraviolet diode-laser-based absorption sensor. APPLIED OPTICS 2005; 44:1491-1502. [PMID: 15796251 DOI: 10.1364/ao.44.001491] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A diode-laser-based sensor has been developed for ultraviolet absorption measurements of the nitric oxide (NO) molecule. The sensor is based on the sum-frequency mixing (SFM) of the output of a tunable, 395-nm external-cavity diode laser and a 532-nm diode-pumped, frequency-doubled Nd:YAG laser in a beta-barium borate crystal. The SFM process generates 325 +/- 75 nW of ultraviolet radiation at 226.8 nm, corresponding to the (v' = 0, v" = 0) band of the A2Sigma+-chi2II electronic transition of NO. Results from initial laboratory experiments in a gas cell are briefly discussed, followed by results from field demonstrations of the sensor for measurements in the exhaust streams of a gas turbine engine and a well-stirred reactor. It is demonstrated that the sensor is capable of fully resolving the absorption spectrum and accurately measuring the NO concentration in actual combustion environments. Absorption is clearly visible in the gas turbine exhaust even for the lowest concentrations of 9 parts per million (ppm) for idle conditions and for a path length of 0.51 m. The sensitivity of the current system is estimated at 0.23%, which corresponds to a detection limit of 0.8 ppm in 1 m for 1000 K gas. The estimated uncertainty in the absolute concentrations that we obtained using the sensor is 10%.
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Affiliation(s)
- Thomas N Anderson
- School of Mechanical Engineering, Purdue University, 585 Purdue Mall, West Lafayette, Indiana 47907-2088, USA.
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Ray GJ, Anderson TN, Caton JA, Lucht RP, Walther T. OH sensor based on ultraviolet, continuous-wave absorption spectroscopy utilizing a frequency-quadrupled, fiber-amplified external-cavity diode laser. OPTICS LETTERS 2001; 26:1870-1872. [PMID: 18059721 DOI: 10.1364/ol.26.001870] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The development of an all-solid-state cw laser system for optical absorption measurements of the OH radical in the UV spectral range is described. The tunable output of a 1064-nm external-cavity diode laser is amplified by use of a Nd:doped, double-clad fiber amplifier. The amplified near-IR radiation is frequency doubled by a periodically poled lithium niobate crystal and then quadrupled in a beta-barium borate crystal. The design and operation of the system and measurements of OH absorption in the (2, 0) band of the A(2)?(+)- X(2)? electronic transition are discussed.
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Kluczynski P, Lindberg AM, Axner O. Background signals in wavelength-modulation spectrometry with frequency-doubled diode-laser light. I. Theory. APPLIED OPTICS 2001; 40:783-793. [PMID: 18357058 DOI: 10.1364/ao.40.000783] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Various types of background signals appear when wavelength-modulated (WM) diode-laser light is frequency doubled. We present a theoretical analysis of such background signals in terms of a previously derived formalism for WM spectrometry that is based on a Fourier series. Explicit expressions for various nf harmonics of the background signals are derived. The analysis shows that 2f detection will be plagued by significant background signals when frequency-doubled WM diode-laser light is used. It also demonstrates that 4f and 6f detection will experience background signals but not, however, to the same extent as 2f detection. The analysis illustrates clearly how the various nf harmonics of the background signals depend on entities such as modulation amplitude, associated intensity modulation, dispersion of the frequency-doubling material, laser power, and detuning. The background signals can take both positive and negative values, depending on the relation between these entities. Guidelines for how to minimize these background signals are given.
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Thoman JW, McIlroy A. Absolute CH Radical Concentrations in Rich Low-Pressure Methane−Oxygen−Argon Flames via Cavity Ringdown Spectroscopy of the A2Δ−X2Π Transition. J Phys Chem A 2000. [DOI: 10.1021/jp0001687] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- John W. Thoman
- Chemistry Department, Williams College, 47 Lab Campus Drive, Williamstown, Massachusetts 01267
| | - Andrew McIlroy
- Combustion Research Facility, Sandia National Laboratories, MS 9055, P.O. Box 969, Livermore, California 94551-0969
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