A discrete integral transform for rapid spectral synthesis

Bekerom, D C M van den; Pannier, Erwan

doi:10.1016/j.jqsrt.2020.107476

Cited by 12 publications

(5 citation statements)

References 27 publications

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“…At the same time, it is also necessary to take the signal-to-noise ratio of the experimental spectrum into account to ensure the accuracy of the constant temperature. Previous research has shown that the water molecules in the ranges of 6400-7600 cm −1 (V1 + V3, V1 + V2 + V3 − V2) and 9500-11 500 cm −1 (4V2 + V3, 2V1 + 2V2, V1 + 2V2 + V3, 2V2 + 2V3, 3V1, 2V1 + V3, V1 + 2V3) [40][41][42] have strong vibration bands; therefore, we selected Group A from table 1 to measure the temperature of the hot gas after methane and oxygen combustion.…”

Section: Temperature Measurement Methods Based On the Integral Ratio ...mentioning

confidence: 99%

Research on flame temperature measurement method based on water vapor emission spectrum

Zhou

Lin

et al. 2023

Meas. Sci. Technol.

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Internal temperature monitoring of high-speed propulsion systems is highly important for engine performance evaluation and lifetime prediction. As a passive optical measurement method without the need for an external light source and without flow field interference, the emission spectrum measurement technique has good application prospects for harsh measurement environments. As the main combustion product, high-temperature water vapor shows a strong emission intensity that is highly suitable for temperature measurement applications. We propose use of the band integral ratio to remove the high resolution measurement requirements for the spectrum acquisition system. In addition, the temperatures of methane-oxygen flames with different equivalent ratios are measured successfully under the condition that the influence of self-absorption on the measurements is considered.

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Section: Temperature Measurement Methods Based On the Integral Ratio ...mentioning

confidence: 99%

Research on flame temperature measurement method based on water vapor emission spectrum

Zhou

Lin

et al. 2023

Meas. Sci. Technol.

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“…Since the total polarization is thus essentially a sum of lineshapes, 𝑃 ̂CRS (𝜔) can be expressed as an integral kernel over the space of lineshape parameters 𝜔 and Γ by following the approach of van den Bekerom and Pannier 27 :…”

Section: Integral Transform Formulationmentioning

confidence: 99%

“…6a and Eq. 7 are discretized by replacing the continuous FT by a discrete FT (DFT) and replacing the integral over Γ by a summation, as summarized in Methods and explained in more detail in van den Bekerom and Pannier 27 . Fig.…”

Section: Integral Transform Formulationmentioning

confidence: 99%

“…In the present work, we introduce a novel algorithm for the rapid synthesis of time-resolved CRS spectra, demonstrating a reduction of the computation time by a factor of 1 M. We refer to this algorithm as "ultrafast", in view of the parallel between this result and the shift from nanosecond to femtosecond lasers, which enabled ultrafast time-resolved spectroscopy 1 . The algorithm is based on the discrete integral transform developed by van den Bekerom and Pannier 27 , who demonstrated a 2-3 orders-of-magnitude reduction in the computational cost of simulating the absorption spectrum of CO2, as compared to the state-of-the-art spectral code RADIS 28 . The accuracy and computational performance of the ultrafast algorithm are assessed against the numerical code of Mazza et al, which models the spectrum of CH4 in the dyad region of its Raman spectrum 26 .…”

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confidence: 99%

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An ultrafast algorithm for ultrafast spectroscopy

Bekerom,

Mazza

2024

Preprint

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Time-resolved coherent Raman spectroscopy (CRS) is a powerful non-linear optical technique for quantitative, in-situ analysis of chemically reacting flows, offering unparalleled accuracy and exceptional spatiotemporal resolution. Its application to large polyatomic molecules, crucial for understanding reaction dynamics, has thus far been limited by the complexity of their rotational-vibrational Raman spectra. Progress in developing comprehensive spectral codes for these molecules, a longstanding goal, has been hindered by prohibitively long computation times required for their spectral synthesis. Here, we present a novel ultrafast algorithm that achieves a million-fold improvement in computation time compared to existing methods. The algorithm demonstrates remarkable accuracy, with an approximation error below 0.1% across all tested probe delays, at both room temperature (296 K) and elevated temperatures (1500 K). This result could greatly expand the application of time-resolved CRS, particularly in plasma research, as well as in broader atmospheric and astrophysical sciences.

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“…Some challenges arise simply due to lack of laboratory data, and some are because of the computational shortcuts used to improve the speed of these often lengthy calculations. Therefore, it is crucial to consider these all differences between the Voigt profiles, broadening treatment, wing cut-off and other details in order to evaluate and cross-check different opacity databases generated by either CPU-based computing codes such as ExoCross and HAPI 25 , or GPU-based codes such as Radis 26 and Helios-K 27 Kochanov et al 2016;van den Bekerom & Pannier 2021;Grimm et al 2021). We briefly discuss the current pressing challenges in producing accurate cross-sections:…”

Section: Current Challenges With Opacitiesmentioning

confidence: 99%

EXOPLINES: Molecular Absorption Cross-Section Database for Brown Dwarf and Giant Exoplanet Atmospheres

Gharib-Nezhad,

Iyer,

Line

et al. 2021

Preprint

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Stellar, substellar, and planetary atmosphere models are all highly sensitive to the input opacities. Generational differences between various state-of-the-art stellar/planetary models are primarily because of incomplete and outdated atomic/molecular line-lists. Here we present a database of precomputed absorption cross-sections for all isotopologues of key atmospheric molecules relevant to latetype stellar, brown dwarf, and planetary atmospheres: MgH, AlH, CaH, TiH, CrH, FeH, SiO, TiO, VO, and H 2 O. The pressure and temperature ranges of the computed opacities are between 10 −6 -3000 bar and 75-4000 K, and their spectral ranges are 0.25-330 µm for many cases where possible. For cases with no pressure-broadening data, we use collision theory to bridge the gap. We also probe the effect of absorption cross-sections calculated from different line lists in the context of Ultra-Hot Jupiter and M-dwarf atmospheres. Using 1-D self-consistent radiative-convective thermochemical equilibrium models, we report significant variations in the theoretical spectra and thermal profiles of substellar atmospheres. With a 2000 K representative Ultra-Hot Jupiter, we report variations of up to 320 and 80 ppm in transmission and thermal emission spectra, respectively. For a 3000 K M-dwarf, we find differences of up to 125% in the spectra. We find that the most significant differences arise due to the choice of TiO line-lists, primarily below 1µm. In sum, we present (1) a database of pre-computed molecular absorption cross-sections, and (2) quantify biases that arise when characterizing substellar/exoplanet atmospheres due to line list differences, therefore highlighting the importance of correct and complete opacities for eventual applications to high precision spectroscopy and photometry.

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A discrete integral transform for rapid spectral synthesis

Cited by 12 publications

References 27 publications

Research on flame temperature measurement method based on water vapor emission spectrum

Research on flame temperature measurement method based on water vapor emission spectrum

An ultrafast algorithm for ultrafast spectroscopy

EXOPLINES: Molecular Absorption Cross-Section Database for Brown Dwarf and Giant Exoplanet Atmospheres

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