1
|
Progresses on the Use of Two-Photon Absorption Laser Induced Fluorescence (TALIF) Diagnostics for Measuring Absolute Atomic Densities in Plasmas and Flames. PLASMA 2021. [DOI: 10.3390/plasma4010009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Recent developments in plasma science and technology have opened new areas of research both for fundamental purposes (e.g., description of key physical phenomena involved in laboratory plasmas) and novel applications (material synthesis, microelectronics, thin film deposition, biomedicine, environment, flow control, to name a few). With the increasing availability of advanced optical diagnostics (fast framing imaging, gas flow visualization, emission/absorption spectroscopy, etc.), a better understanding of the physicochemical processes taking place in different electrical discharges has been achieved. In this direction, the implementation of fast (ns) and ultrafast (ps and fs) lasers has been essential for the precise determination of the electron density and temperature, the axial and radial gradients of electric fields, the gas temperature, and the absolute density of ground-state reactive atoms and molecules in non-equilibrium plasmas. For those species, the use of laser-based spectroscopy has led to their in situ quantification with high temporal and spatial resolution, with excellent sensitivity. The present review is dedicated to the advances of two-photon absorption laser induced fluorescence (TALIF) techniques for the measurement of reactive species densities (particularly atoms such as N, H and O) in a wide range of pressures in plasmas and flames. The requirements for the appropriate implementation of TALIF techniques as well as their fundamental principles are presented based on representative published works. The limitations on the density determination imposed by different factors are also discussed. These may refer to the increasing pressure of the probed medium (leading to a significant collisional quenching of excited states), and other issues originating in the high instantaneous power density of the lasers used (such as photodissociation, amplified stimulated emission, and photoionization, resulting to the saturation of the optical transition of interest).
Collapse
|
2
|
Abstract
Many important chemically reacting systems are inherently multi-dimensional with spatial and temporal variations in the thermochemical state, which can be strongly coupled to interactions with transport processes. Fundamental insights into these systems require multi-dimensional measurements of the thermochemical state as well as fluid dynamics quantities. Laser-based imaging diagnostics provide spatially and temporally resolved measurements that help address this need. The state of the art in imaging diagnostics is continually progressing with the goal of attaining simultaneous multi-parameter measurements that capture transient processes, particularly those that lead to stochastic events, such as localized extinction in turbulent combustion. Development efforts in imaging diagnostics benefit from advances in laser and detector technology. This article provides a perspective on the progression of increasing dimensionality of laser-based imaging diagnostics and highlights the evolution from single-point measurements to 1D and 2D multi-parameter imaging and 3D high-speed imaging. This evolution is demonstrated using highlights of laser-based imaging techniques in combustion science research as an exemplar of a complex multi-dimensional chemically reacting system with chemistry-transport coupling. Imaging diagnostics impact basic research in other chemically reacting systems as well, such as measurements of near-surface gases in heterogeneous catalysis. The expanding dimensionality of imaging diagnostics leads to larger and more complex datasets that require increasingly demanding approaches to data analysis and provide opportunities for increased collaboration between experimental and computational researchers in tackling these challenges.
Collapse
Affiliation(s)
- Jonathan H Frank
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, USA
| |
Collapse
|
3
|
Ruchkina M, Ding P, Aldén M, Bood J, Brackmann C. Two-photon-excited fluorescence of CO: experiments and modeling. OPTICS EXPRESS 2019; 27:25656-25669. [PMID: 31510434 DOI: 10.1364/oe.27.025656] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 07/17/2019] [Indexed: 06/10/2023]
Abstract
A model based on rate-equation analysis has been developed for simulation of two-photon-excited laser-induced fluorescence of carbon monoxide (CO) in the Hopfield-Birge band at 230 nm. The model has been compared with experimental fluorescence profiles measured along focused beams provided by lasers emitting nano-, pico-, and femtosecond pulses. Good quantitative agreement was obtained between simulations and experimental data obtained in premixed CH4/C2H4-air flames. For excitation with femtosecond pulses, experimental and simulated fluorescence signals showed quadratic dependence on laser power under conditions of low laser irradiance, whereas different sublinear dependencies were obtained at higher irradiances due to photoionization. Simulations of CO signal versus femtosecond laser linewidth suggest the strongest signal for a transform-limited pulse, which is sufficiently broad spectrally to cover the CO Q-branch absorption spectrum. Altogether, the developed rate-equation model allows for analysis of two-photon excitation fluorescence to arrange suitable diagnostic configurations and retrieve quantitative data for CO as well as other species in combustion, such as atomic oxygen and hydrogen.
Collapse
|
4
|
Rahman KA, Athmanathan V, Slipchenko MN, Roy S, Gord JR, Zhang Z, Meyer TR. Quantitative femtosecond, two-photon laser-induced fluorescence of atomic oxygen in high-pressure flames. APPLIED OPTICS 2019; 58:1984-1990. [PMID: 30874065 DOI: 10.1364/ao.58.001984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 02/06/2019] [Indexed: 06/09/2023]
Abstract
Quantitative femtosecond two-photon laser-induced fluorescence of atomic oxygen was demonstrated in an H2/air flame at pressures up to 10 atm. Femtosecond excitation at 226.1 nm was used to pump the 3pP3J'=0,1,2←←2pP3J''=0,1,2 electronic transition of atomic oxygen. Contributions from multiphoton de-excitation, production of atomic oxygen, and photolytic interferences were investigated and minimized by limiting the laser irradiance to ∼1011 W/cm2. Quantitative agreement was achieved with the theoretical equilibrium mole fraction of atomic oxygen over a wide range of fuel-air ratios and pressures in an H2/air laminar calibration burner.
Collapse
|
5
|
Patnaik AK, Adamovich I, Gord JR, Roy S. Recent advances in ultrafast-laser-based spectroscopy and imaging for reacting plasmas and flames. ACTA ACUST UNITED AC 2017. [DOI: 10.1088/1361-6595/aa8578] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
6
|
Meißner C, Tröger JW, Kozlov DN, Beyrau F, Seeger T. Three-color vibrational CARS thermometry of fuel-rich ethylene/air flames using a potassium gadolinium tungstate Raman-active crystal as a source of narrowband probe radiation. APPLIED OPTICS 2017; 56:E77-E83. [PMID: 28414345 DOI: 10.1364/ao.56.000e77] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Three-color broadband vibrational coherent anti-Stokes Raman scattering (CARS) temperature measurements were carried out in laminar fuel-rich sooting ethylene/air flames. Stimulated Raman scattering (SRS) of a picosecond pump laser pulse in a Raman-active potassium gadolinium tungstate [KGd(WO4)2] crystal was employed as a source of narrowband probe radiation. In the three-color CARS experiment, this wavelength-shifted radiation enables N2-based vibrational CARS temperature measurements in sooting flames free of the signal interference with the absorption/emission bands of the flame intermediate radicals C2. Spatial temperature profiles for different fuel-rich atmospheric pressure ethylene/air flames are presented in comparison with the results of two-color broadband vibrational and dual-broadband pure rotational CARS temperature measurements. The comparison shows the suitability of the three-color CARS measurement technique employing the KGd(WO4)2 crystal for accurate, C2 interference-free, temperature measurements in sooting flames.
Collapse
|
7
|
Richardson DR, Roy S, Gord JR. Femtosecond, two-photon, planar laser-induced fluorescence of carbon monoxide in flames. OPTICS LETTERS 2017; 42:875-878. [PMID: 28198887 DOI: 10.1364/ol.42.000875] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Two-photon, planar laser-induced fluorescence (TP-PLIF) of carbon monoxide was performed in steady and driven flames using femtosecond (fs) laser pulses at 1 kHz. Excitation radiation at 230.1 nm (full-width at half-maximum bandwidth of 270 cm-1) was used to pump many rovibrational two-photon transitions in the B1∑+←X1∑+ system. Visible fluorescence in the range 362-516 nm was captured using an image intensifier and high-speed camera. The signal dependence on excitation energy and wavelength is presented. Photolytic interferences from the ultraviolet laser were explored in a sooting diffusion flame. Using an excitation laser intensity of 1010 W/cm2, negligible photolytic interferences were observed, and PLIF imaging of dynamic flame events was performed at 1 kHz.
Collapse
|
8
|
Kulatilaka WD, Gord JR, Katta VR, Roy S. Photolytic-interference-free, femtosecond two-photon fluorescence imaging of atomic hydrogen. OPTICS LETTERS 2012; 37:3051-3053. [PMID: 22859082 DOI: 10.1364/ol.37.003051] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We discuss photolytic-interference-free, high-repetition-rate imaging of reaction intermediates in flames and plasmas using femtosecond (fs) multiphoton excitation. The high peak power of fs pulses enables efficient nonlinear excitation, while the low energy nearly eliminates interfering single-photon photodissociation processes. We demonstrate proof-of-principle, interference-free, two-photon laser-induced fluorescence line imaging of atomic hydrogen in hydrocarbon flames and discuss the method's implications for certain other atomic and molecular species.
Collapse
|
9
|
Li X, Zhao Y, Ma L. Method to correct the distortion caused by amplified stimulated emission as motivated by LIF-based flow diagnostics. APPLIED OPTICS 2012; 51:2107-2117. [PMID: 22534923 DOI: 10.1364/ao.51.002107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 01/19/2012] [Indexed: 05/31/2023]
Abstract
Amplified stimulated emission (ASE) represents a significant issue in two-photon laser-induced fluorescence (TPLIF). The ASE effects are nonlinear and nonlocal, i.e., the ASE effects distort the LIF signal nonlinearly, and the distortion at one location depends on conditions at other locations. In this sense, the ASE effects pose a greater challenge to quantitative TPLIF than quenching and ionization. This work therefore seeks a method to correct such distortion. The method uses two LIF measurements, one with low signal-to-noise ratio (SNR) and negligible ASE distortion and another with high SNR but significant distortion, to generate a faithful measurement with high SNR. Extensive simulations were performed to evaluate the performance of this method for practical applications.
Collapse
Affiliation(s)
- Xuesong Li
- Department of Aerospace and Ocean Engineering, Virginia Tech, Blacksburg, Virginia 24061, USA
| | | | | |
Collapse
|
10
|
Kulatilaka WD, Patterson BD, Frank JH, Settersten TB. Comparison of nanosecond and picosecond excitation for interference-free two-photon laser-induced fluorescence detection of atomic hydrogen in flames. APPLIED OPTICS 2008; 47:4672-4683. [PMID: 18784770 DOI: 10.1364/ao.47.004672] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Two-photon laser-induced fluorescence (TP-LIF) line imaging of atomic hydrogen was investigated in a series of premixed CH4/O2/N2, H2/O2, and H2/O2/N2 flames using excitation with either picosecond or nanosecond pulsed lasers operating at 205 nm. Radial TP-LIF profiles were measured for a range of pulse fluences to determine the maximum interference-free signal levels and the corresponding picosecond and nanosecond laser fluences in each of 12 flames. For an interference-free measurement, the shape of the TP-LIF profile is independent of laser fluence. For larger fluences, distortions in the profile are attributed to photodissociation of H2O, CH3, and/or other combustion intermediates, and stimulated emission. In comparison with the nanosecond laser, excitation with the picosecond laser can effectively reduce the photolytic interference and produces approximately an order of magnitude larger interference-free signal in CH4/O2/N2 flames with equivalence ratios in the range of 0.5< or =Phi< or =1.4, and in H2/O2 flames with 0.3< or =Phi< or =1.2. Although photolytic interference limits the nanosecond laser fluence in all flames, stimulated emission, occurring between the laser-excited level, H(n=3), and H(n=2), is the limiting factor for picosecond excitation in the flames with the highest H atom concentration. Nanosecond excitation is advantageous in the richest (Phi=1.64) CH4/O2/N2 flame and in H2/O2/N2 flames. The optimal excitation pulse width for interference-free H atom detection depends on the relative concentrations of hydrogen atoms and photolytic precursors, the flame temperature, and the laser path length within the flame.
Collapse
Affiliation(s)
- Waruna D Kulatilaka
- Combustion Research Facility, Sandia National Laboratories, PO Box 969, Livermore, California 94551, USA
| | | | | | | |
Collapse
|
11
|
Gord JR, Meyer TR, Roy S. Applications of ultrafast lasers for optical measurements in combusting flows. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2008; 1:663-687. [PMID: 20636093 DOI: 10.1146/annurev.anchem.1.031207.112957] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Optical measurement techniques are powerful tools for the detailed study of combustion chemistry and physics. Although traditional combustion diagnostics based on continuous-wave and nanosecond-pulsed lasers continue to dominate fundamental combustion studies and applications in reacting flows, revolutionary advances in the science and engineering of ultrafast (picosecond- and femtosecond-pulsed) lasers are driving the enhancement of existing diagnostic techniques and enabling the development of new measurement approaches. The ultrashort pulses afforded by these new laser systems provide unprecedented temporal resolution for studies of chemical kinetics and dynamics, freedom from collisional-quenching effects, and tremendous peak powers for broad spectral coverage and nonlinear signal generation. The high pulse-repetition rates of ultrafast oscillators and amplifiers allow previously unachievable data-acquisition bandwidths for the study of turbulence and combustion instabilities. We review applications of ultrafast lasers for optical measurements in combusting flows and sprays, emphasizing recent achievements and future opportunities.
Collapse
Affiliation(s)
- James R Gord
- Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, USA.
| | | | | |
Collapse
|
12
|
Linvin M, Li ZS, Zetterberg J, Aldén M. Single-shot imaging of ground-state hydrogen atoms with a nonlinear laser spectroscopic technique. OPTICS LETTERS 2007; 32:1569-71. [PMID: 17546191 DOI: 10.1364/ol.32.001569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
We report on a novel nonlinear laser spectroscopic technique for single-shot imaging of ground-state hydrogen atoms in harsh environments. H atoms from the ground state were first pumped to the 2s state via a two-photon excitation with a 243 nm laser beam, and the population of the 2s state was further probed through the 2s-4p transition with conventional polarization spectroscopy at 486 nm. A single Nd:YAG-pumped optical parametric oscillator laser system was enough to provide both laser beams. Single-shot visualization of native H atoms in an atmospheric pressure premixed H(2)/O(2) flame is demonstrated.
Collapse
Affiliation(s)
- M Linvin
- Division of Combustion Physics, Lund University, Lund, Sweden
| | | | | | | |
Collapse
|
13
|
Martin GC, Mueller CJ, Lee CFF. Two-photon nitric oxide laser-induced fluorescence measurements in a diesel engine. APPLIED OPTICS 2006; 45:2089-100. [PMID: 16579580 DOI: 10.1364/ao.45.002089] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
A two-photon nitric oxide (NO) laser-induced fluorescence (LIF) technique was developed and applied to study in-cylinder diesel combustion. The technique prevents many problems associated with in-cylinder, single-photon NO planar-laser-induced fluorescence measurements, including fluorescence interference from the Schumann-Runge bands of hot O2, absorption of a UV excitation beam by in-cylinder gases, and difficulty in rejecting scattered laser light while simultaneously attempting to maximize fluorescence signal collection. Verification that the signal resulted from NO was provided by tuning of the laser to a vibrational off-resonance wavelength that showed near-zero signal levels, which resulted from either fluorescence or interference at in-cylinder pressures of as much as 20 bar. The two-photon NO LIF signal showed good qualitative agreement with NO exhaust-gas measurements obtained over a wide range of engine loads.
Collapse
Affiliation(s)
- Glen C Martin
- Sandia National Laboratories, MS9053, P.O. Box 969, Livermore, California 94551-0969, USA.
| | | | | |
Collapse
|
14
|
Teslja A, Dagdigian PJ. Determination of oxygen atom concentrations by cavity ring-down spectroscopy. Chem Phys Lett 2004. [DOI: 10.1016/j.cplett.2004.11.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
15
|
Lucht RP, Roy S, Gord JR. Nonperturbative modeling of two-photon absorption in a three-state system. J Chem Phys 2004; 121:9820-9. [PMID: 15549855 DOI: 10.1063/1.1809572] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The physics of the two-photon absorption process is investigated for a three-state system. The density-matrix equations for the two-photon interaction are solved in the steady-state limit assuming that the pump laser radiation is monochromatic. Collisional broadening, saturation, and Stark shifting of the two-photon resonance are investigated in detail by numerical solution of the steady-state density-matrix equations. Analytical expressions for the saturation intensity and the Stark shift are derived for the case where the single-photon transitions between the intermediate state and the initial and final states are far from resonance with the pump laser. For this case, it is found that the direction of the Stark shift is dependent on the relative magnitudes of the dipole-moment matrix elements for the single-photon transitions that couple the intermediate state with the initial and final states. Saturation and Stark shifting are also investigated for the case where the single-photon transitions between the intermediate state and the initial and final states are close to resonance with the pump laser.
Collapse
Affiliation(s)
- Robert P Lucht
- School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907-2088, USA.
| | | | | |
Collapse
|