The aviation sector's transition to sustainable energy requires characterizing novel e-fuel candidates such as tetrahydrofuran (THF) and isopropanol. This study investigates the autoignition properties of THF/isopropanol blends under lean conditions (ϕ = 0.25, 0.5 and 0.9) relevant to Lean Premixed Prevaporized (LPP) combustion. Shock tube experiments were conducted at 0.89–1.41 atm and 1280–1788 K, measuring ignition delay times (IDT) via OH* chemiluminescence and time-resolved CO histories via Tunable Diode Laser Absorption Spectroscopy (TDLAS) across isopropanol mole fractions of 0–50%. A recently developed kinetic mechanism for THF/isopropanol blends, validated against Jet Stirred Reactor data from our group, was found to exhibit discrepancies under shock tube conditions. To resolve these, a Surrogate-Assisted Genetic Algorithm (SAGA) framework was developed, coupling Deep Neural Network (DNN) surrogates with a genetic optimizer to simultaneously adjust 26 key pre-exponential factors. The DNN surrogates achieved R2 > 0.999 on independent test data and reduced end-to-end optimization time by approximately three orders of magnitude. The optimizer converged consistently across 1000 independent trials, with 88% of function values within 5% of the global best. The optimized mechanism shows excellent agreement with measured IDTs and CO profiles and is cross-validated against independent laminar flame speed data not included in the optimization targets. Applied to LPP operability, the mechanism indicates a trade-off between flashback propensity and blowout resistance, with a favourable operating point near ϕ = 0.65 and 0–50% THF that is largely preserved across the pressures examined.

A traceable experimental validation of hydrogen (H2) quantification by direct tunable diode laser absorption spectroscopy (d-TDLAS) is reported using two isolated near-infrared quadrupole transitions at 2121.8 and 2222 nm. Measurements were performed on a common dual-wavelength platform with a Herriott-type multipass cell providing an effective optical path length of 3122.7±2 cm. Spectra were evaluated by etalon-based spectral-axis reconstruction and Hartmann-Tran profile fitting. To assess robustness, pure-H2 pressure-series experiments were repeated independently in 2025 and 2026, and each dataset was evaluated without empirical recalibration. The study examines Beer-Lambert pressure scaling, pressure-normalized integrated-absorbance stability, repeatability of independently retrieved absorbance observables, and spectroscopic consistency of derived line strengths with HITRAN reference data. For the stronger 2121.8 nm transition, the retained 2025 and 2026 datasets were pooled, yielding a dataset-level reproducibility of 1.11% in 〈AUC/p〉 and a standard uncertainty of the mean of 0.39%. For the weaker 2222 nm transition, the final analysis was restricted to retained 2025 datasets, giving an intra-campaign scatter of 1.35%. Propagation through the Beer-Lambert relation gives line strengths of S = (3.014 ± 0.034) × 10−26 cm/molecule at 2121.8 nm and S = (1.045 ± 0.045) × 10−26 cm/molecule at 2222 nm, with fit residuals at the 𝒪 (10−4) absorbance level. These values differ from HITRAN by -5.5% and -3.1% respectively, both within the HITRAN uncertainty class for these weak quadrupole transitions. The results establish a practical metrological basis for SI-traceable, calibration-free H2 quantification by direct absorption spectroscopy.

As global climate goals drive the transition away from high-GWP refrigerants, understanding the combustion behavior of low- and medium-GWP alternatives is essential for emissions control and fire safety assessment. This study presents a combined experimental and modeling investigation of difluoromethane (CH2F2, R32), methane (CH4, R50), and their blends. Shock tube experiments were performed over 1477-2236 K at 0.98-1.15 bar for phi = 0.5-2.0, with ignition delay times (IDTs) determined from time-resolved CO measurements using laser absorption spectroscopy. Complementary laminar flame speed data for CH2F2 and CH2F2/CH4 blends supported model validation. CH2F2 ignited 4-10 times faster than CH4, while blends exhibited intermediate but nonlinear IDTs due to radical cross-interactions. Time-resolved CO profiles showed broad peaks for CH2F2-containing mixtures, unlike the sharp CO peaks of CH4, indicating prolonged intermediate chemistry involving CHF, CHF2, CHFO, CF2O, and HF. Laminar flame speeds confirmed slower propagation for CH2F2 compared to CH4, while CH4 addition increased sensitivity to oxidizer composition. Kinetic analysis revealed that CH2F2 ignition is dominated by fluorine-centered pathways involving unimolecular decomposition and H-abstraction forming CHF/CHF2 radicals, with CF2O and HF as major termination products, whereas CH4 follows conventional H/O chain branching. Genetic algorithm optimization of 18 sensitive reactions within uncertainty bounds reduced IDT prediction errors by 71 % for CH2F2 and 63 % for CH2F2/CH4 blends. The optimized mechanism improved CO and flame speed predictions, achieving good agreement with experimental data within reported uncertainties. This integrated framework refines the high-temperature oxidation chemistry of fluorinated refrigerants and provides a validated mechanism for reliable fire safety evaluation.

This study presents simultaneous time-resolved measurements of NH3, N2O, and NO concentration profiles in NH3/N2O/Ar mixtures behind reflected shock waves using tunable diode laser absorption spectroscopy (TDLAS). Spectrally resolved N2O absorption cross-sections were measured near 2193 cm−1 over 909–2113 K. Three equivalence ratios (φ = 0.5, 1.0, and 2.0) with an argon dilution ratio of 95% were investigated at temperatures of 1687–2235 K and pressures of 1.0–1.3 bar. Building on these data, the PTB-NH3/C2 mechanism was upgraded from v1.1 to v1.2. The key update is the adoption of the HNNO sub-mechanism for the H + N2O system, together with updated N2O + O = N2 + O2 and N2H2 + NO = N2O + NH2 rates consistent with recent ab initio determinations. A bounded multi-target genetic algorithm then refined nine sensitive pre-exponential factors within their uncertainty intervals. This upgrade reduced the mean absolute relative discrepancy in peak NO mole fraction from 38.8% to 10.7%, with consistent gains for the NH3 and N2O half-consumption times and the NO half-rise time. Sensitivity and pathway analyses show that the corrected N2O + O and N2H2 + NO rates remove spurious NO formation and resolve the systematic NO over-prediction, while the H + N2O channel, now described via the HNNO chemistry, together with thermal N2O decomposition governs the N2O consumption budget. Cross-validation against independent datasets confirmed that v1.2 is physically consistent and transferable beyond the training conditions.

A traceable validation of the tunable diode laser absorption spectroscopy (TDLAS) measurement chain for hydrogen (H2), with line-strength determination, is reported for two near-infrared quadrupole transitions at 2121.8 nm and 2222 nm. Measurements used a dual-wavelength Herriott-type multipass cell with an effective optical path length of 3122.7 ± 2 cm. Spectra were evaluated by etalon-based spectral-axis reconstruction and constrained Hartmann–Tran-type (HTP-type) non-Voigt fitting; the area-normalized fit retrieves the integrated absorbance A, and Beer–Lambert pressure scaling of A yields the line strength, forming a single retrieval chain. Pure-H2 pressure-series experiments were repeated in independent measurement campaigns and evaluated without empirical recalibration. For the stronger 2121.8 nm transition, the repeated datasets gave a dataset-level reproducibility of 1.11% in A/p and a standard uncertainty of the mean of 0.39%. For the weaker 2222 nm transition, the evaluated datasets gave a dataset-level scatter of 1.35%. The resulting line strengths are S = (3.014 ± 0.034) × 10−26 cm molecule−1 at 2121.8 nm and S = (1.057 ± 0.014) × 10−26 cm molecule−1 at 2222 nm, deviating from HITRAN by -5.49% and -2.05%, respectively. Because the HITRAN intensities carry an assigned uncertainty of 0.1–1% (intensity uncertainty code 8), these deviations exceed the combined stated uncertainties, indicating a residual systematic contribution. The work establishes an SI-traceable direct-absorption chain for H2 quadrupole spectroscopy.

Nitrous oxide (N 2 O) is gaining interest in maritime applications for several reasons, primarily related to engine performance enhancement, emissions reduction, and auxiliary power supply. While N 2 O can enhance combustion efficiency and reduce certain emissions, uncontrolled use could result in increased NO x formation and other pollutants. Effective N 2 O monitoring is critical in maritime applications for ensuring operational safety, regulatory compliance, and optimal performance. We introduce an innovative first-principles N 2 O spectrometer designed specifically for maritime applications, such as monitoring emissions during and after combustion processes. This TDLAS based spectrometer targets the P29e line at 4.55 µm spectral band and provides direct absolute mole fraction measurements, eliminating the necessity for prior or routine calibration.

This study presents a comprehensive spectroscopic investigation of two nitric oxide (NO) absorption transitions (R11.5 Ω1/2 at 1914.99 cm-1 and R11.5 Ω3/2 at 1915.76 cm-1) using laser absorption spectroscopy. By employing two complementary experimental systems, namely a continuous flow gas cell for line intensity measurements and a shock tube facility for temperature dependence coefficient characterization, we attained exceptional measurement accuracy with line intensity uncertainties as low as 0.95 % while extending the accessible temperature range to 1742 K. The study systematically characterizes temperature dependence of pressure broadening coefficients in four buffer gases (Ar, N2, He, CO2), revealing distinct gas-specific behaviors, particularly the weak interaction between NO and helium. A rigorous metrological analysis demonstrated substantial improvements in NO quantification accuracy, achieving 12.4-fold and 3.5-fold uncertainty reductions for scanned-wavelength and fixed-wavelength LAS, respectively. The development of uncertainty mapping and dynamic uncertainty evaluation methodologies further enhanced measurement reliability under transient conditions. The comprehensive dataset and methodological innovations presented in this work address critical gaps in high temperature NO spectroscopy and enable more accurate molecular diagnostics in energy, environmental, and industrial applications.

The oxidation of toluene in the presence of nitrous oxide (N2O) is investigated experimentally using shock tubes, and the results are simulated using an improved chemical kinetic model. The improved model is based on GalwayMech1.0 with updated rate constants for the reactions C(center dot)6H5 + H-center dot (+M) <-> C6H6 (+M), N2O (+M) <-> N2 + O (+M), N2O + H-center dot <-> N2 + (OH)-H-center dot, N2O + O <-> NO + NO, and N2O + O <-> N2 + O2. Additionally, the current model includes HNNO and NHNO intermediate chemistry. The proposed mechanism is validated over a wide range of temperatures and equivalence ratios, with validation targets including experimental data for toluene, H2/N2O, and newly generated toluene/N2O blend data from shock tubes. High-pressure shock tube experiments reveal that the toluene/N2O mixture is highly susceptible to pre-ignition at low temperatures. The chemical kinetic analysis indicates that the ignition of the toluene/N2O mixtures is highly sensitive to the N2O (+M) <-> N2 + O (+M) reaction. The heat released, along with the O atoms generated during the decomposition of N2O, causes the rapid depletion of toluene at a substantially faster rate than N2O. Similarly, H-center dot atoms, mostly produced from toluene chemistry, e.g., through benzyl radical breakup C6H5C(center dot)H2 <-> C(center dot)7H6 + H-center dot, help the decomposition of N2O molecules via N2O + H-center dot <-> NO + NH. Moreover, other major nitric oxide (NO) producing reactions are identified, including N2O + O <-> NO + NO and NH + O <-> NO + H-center dot. Due to the rapid depletion of toluene, direct chemical interactions between N2O and the aromatic ring have little influence on overall combustion chemistry. However, the enthalpy of formation of toluene and benzyl radical do influence N2O decomposition significantly.

This study investigates fast and accurate sensing in dynamic conditions using the intrapulse laser technique. The spectral range of 1914-1916 cm(-)(1) , encompassing NO and H2O absorption peaks, allows simultaneous measurements of NO and H2O mole fractions and temperature via two-line thermometry. The intrapulse laser operates at a 900 kHz repetition rate with a 200 ns pulse width, achieving time resolution comparable to fixed-wavelength methods. With a chirp rate of 250-400 MHz, it provides spectral resolution of 0.0156-0.0197 cm(-)(1) . A novel method to correct the rapid passage effect under low-pressure conditions, by symmetrically flipping half of the unaffected spectrum, is proposed and validated. Specific experiments show that NO and H2O measurements from the intrapulse laser align with those from an Interband Cascade Laser (ICL)-NO laser and a Distributed Feedback (DFB)-H2O laser, respectively. Temperature measurements correlate well with one-dimensional shock calculations. The average relative differences for NO mole fraction, H2O mole fraction, and temperature are 4.5 %, 7.0 %, and 5.4 %, respectively. In NH3 oxidation experiments, the intrapulse laser captures dynamic formation processes of NO and H2O, along with temperature variations, in good agreement with chemical simulation results. This technique combines the calibration-free advantage of scanned-wavelength methods with the high time resolution of fixed-wavelength methods, making it a powerful tool for simultaneous multi-species and temperature measurements in dynamic environments.

Ignition delay times (IDT) and speciation profiles (NH3, NO, and CO) were measured for NH3/C-1 fuel blends (NH3/CO, NH3/CH4, NH3/CH3OH) in a shock tube using laser absorption spectroscopy. Experiments spanned equivalence ratios of 0.5-1.5, 5-20 % C-1 additives, and temperatures of 1477-2236 K at around 2.5 bar. The experimental data were validated against the simulation results from the PTB-NH3/C-2 1.1 mechanism, which demonstrated robust performance across all mixtures. Methanol significantly enhances ignition reactivity, resulting in the shortest IDTs among the three C-1 additives. Combining the findings from our prior studies, the IDT reduction order by different hydrocarbons at high temperatures is: C2H5OH approximate to C2H6 > CH3OH > CH4 > CO, indicating that high temperature favors C-2 compounds. While at intermediate temperatures and high pressures, where the functional groups dominate, the reactivity order is: C2H5OH > CH3OH > C2H6 > CH4, as alcohols enhance reactivity stronger than alkanes. Kinetic modeling analysis identified NH2 as a key intermediate in NH3 oxidation, following the primary pathway NH3 -> NH2 -> NH -> N -> NO. For NH3/CO, CO contributed to secondary branching intermediates like HNCO through reactions like NH2 + CO <=> HNCO + H, influencing nitrogen-carbon interactions. In NH3/CH4, hydrocarbon oxidation promoted CO and CH2O formation, with limited CN cross-reactions. NH3/CH3OH pathways exhibited unique CH3O and CH2OH radical dynamics, facilitating prolonged CO formation and unique broader CO peaks under fuel-rich conditions. While the PTB-NH3/C-2 1.1 mechanism captured most trends, discrepancies emerged at lower temperatures and fuel-rich conditions, underscoring the need for further improvement in future. Measuring more intermediate species such as N2O, NO2, and CH2O would also benefit model validation.

The addition of hydrogen (H-2) to liquefied natural gas (LNG) is a promising approach for decarbonizing internal combustion engines, but it introduces challenges related to ignition behavior and NOx emissions. This study provides a kinetically grounded demonstration that water addition is a highly effective dual-action strategy for simultaneously mitigating both NOx and CO emissions in hydrogen-enriched natural gas engines. By integrating shock tube experiments with HCCI engine simulations, we address the trade-off between decarbonization and emissions. First, the autoignition and CO formation of LNG and LNG/H-2 blends were characterized in a shock tube at temperatures of 1400-1800 K using Tunable Diode Laser Absorption Spectroscopy (TDLAS). After evaluating the most recent literature kinetic models, the NUIG 1.3 mechanism was selected due to its better predictive capabilities for the blends under investigation. The addition of hydrogen to LNG shows contrary effect on the correlation between the ignition delay time and methane number (MN) at different temperature regimes, i.e, the hydrogen lowers the MN at high temperatures (similar to 1200 K) and raises the MN at low temperatures (800 K). Reaction pathway analysis demonstrates that water enriches the OH radical pool, which both accelerates the final CO oxidation step and chemically suppresses NOx formation pathways. These findings provide a validated kinetic framework for optimizing water injection strategies, offering a viable pathway to enable the use of high-fraction hydrogen blends in internal combustion engines while meeting future emissions regulations.

Two laser absorption spectroscopy (LAS)-based spectrometers have been developed for measuring carbon monoxide (CO) pressure broadening and temperature dependency coefficients in the 1 ← 0 band. Using a scanned-wavelength LAS at 140 Hz, pressure broadening coefficients of four CO transition lines P(16), P(20), P(26), and P(27), perturbed by Ar, He, H2, O2, N2, CO2, and Air have been systematically measured in a gas cell using a consistent metrological approach. Results indicate that the CO pressure broadening coefficient decreases monotonically as the line number |m| increases. The variation of pressure broadening coefficients at different buffer gases follow a consistent trend for all four measured lines: CO-H2 and CO-Ar show the highest and lowest pressure broadening coefficients, respectively. Compared to the literature results with relatively large uncertainties or even unavaible uncertainty information, the uncertainty of measured pressure broadening coefficients is below 1% for most cases. Further, using a scanned-wavelength LAS at 20 kHz, temperature dependence coefficients of P(20) in Ar, He, N2 and CO2 were measured at a temperature range of 430-1648 K in a shock tube. With this rapid scan frequency, the spectrum between incident shock and reflected shock was also used for temperature dependence coefficient calculation. The uncertainty of the measured temperature dependence coefficients are under 6.2%. Toward combustion systems as an application case, the CO mole fraction during CH4 oxidation in the shock tube was quantified using a fixed-wavelength LAS. The results reveal that the uncertainty in CO mole fraction was reduced by a factor of 2.7 when using the line parameters obtained in this study compared to those from the HITRAN database. Thus, the newly measured data with low uncertainties substantially enhance the spectroscopic database, enabling more precise CO mole fraction quantification across a range of application scenarios such as environmental monitoring, industrial control, safety monitoring, medicine, astronomy, and scientific research.

Growing concern over refrigerants' environmental impact drives interest in low global warming potential (GWP) alternatives like hydrocarbon-based refrigerants (HCs) such as butane, propane, ethane, methane, isobutene, ethylene, and propylene. R32, R-1234yf, and R-1234ze are favored due to their lower GWP and superior energy efficiency. Comparing the environmental impacts of R-1234yf (4/100 yr) and R-1234ze (7/100 yr) explains potential hazards and toxicity, while investigating R32's (675/100 yr) ignition behavior enhances understanding of fluorinated compound oxidation, emphasizing safety in environmental assessments. To address this, state-of-the-art techniques combining a shock tube and tunable diode laser absorption spectroscopy (TDLAS) were used to measure ignition delay, hazard product formation like carbon monoxide, and energy release behind shock waves, aiding safety evaluations and supporting predictive chemical kinetic mechanisms for numerical simulations.

A mid -infrared quantum cascade laser (Mid-IR QCL) coupled with a Single Pass Cell and a Multi Pass Cell, was utilized to measure ammonia (NH 3 ) absorption spectroscopic parameters and determine NH 3 impurities toward three emerging applications. We for the first time measured the pressure broadening coefficients perturbed by Air, O 2 , N 2 , He, CO 2 , CH 4 , and H 2 and the line intensities of six NH 3 transition lines near 1084.6 cm - 1 . The measured NH 3 -He, NH 3 -Air, and NH 3 -CO 2 broadening coefficients align with HITRAN database, while NH 3 -H 2 coefficients exhibit a maximum discrepancy of 46 %. Deviations between the measured line intensities and HITRAN database are minimal. Nevertheless, the uncertainties of line intensities have been significantly reduced from 20 % in HITRAN to below 3 %. The newly measured line parameters are utilized to address NH 3 impurity requirements outlined in CCUS (ISO 27913:2016), Biomethane (EN 16723:2016), and H 2 (ISO 14687:2019) standards. Based on the concept of optical gas standard (OGS), the NH 3 impurity detection requirements in all three standards have been fulfilled with an uncertainty of 1.35 %. The precision of the NH 3 -OGS is 800 part per trillion (ppt) with an integration time of 100 s. The repeatability of the NH 3 -OGS is 130 ppt for a continuous measurement time of 48 min. Notably, the NH 3 -OGS effectively addresses the highly nonlinear adsorption-desorption dynamics, underscoring the potential of OGS as a calibration -free and SI-traceable metrological gas analysis instrument.

This study examines NH3, NO, and CO profiles during NH3/C2H6 and NH3/C2H5OH oxidation in a shock tube using laser absorption spectroscopy at 1317-1957 K and similar to 2.8 bar, with 5-20% C2H6 or C2H5OH, equivalence ratios of 0.5/1.0/1.5, and a 0.9 argon dilution ratio. Metrological uncertainty analysis on mole fractions have been performed. A novel dynamic uncertainty methodology is proposed to time-resolved speciation profiles. From the experimental measurements, the promotional effect on ammonia ignition by C2H6 or C2H5OH is identical under investigated conditions. The multi-speciation profiles demonstrate reasonable relations among the consumption of NH3 and the formation of NO and CO, which show strong temperature and equivalence ratio dependence. An updated PTB-NH3/C-2 1.1 mechanism accurately predicts ignition delay times and speciation profiles. Sensitivity analysis reveals NH3 chemistry's significant control, with NH3+O-2/H/OH and N2H2+M reactions being critical at >1300 K, and HO2 interactions being pivotal at 800-1200 K. The reactions related to N2H2 and N-C chemistries dominate for fuel-rich mixtures at high temperatures, resulting in a reverse equivalence ratio dependence on IDTs, namely fuel-rich mixtures exhibit the lowest reactivity. The N-C chemistries, particularly the pronounced reaction pathway of HCN -> CN -> NCO -> HNCO -> CO play a crucial role in maintaining the CO level constant after reaching its peak position under fuel-rich conditionsNH3 consumption pathways shift from NH2 -> H2NO -> HNO -> NO -> NO2 -> N2O -> N-2 at intermediate temperatures to NH3 -> NH2 -> NH -> N(HNO)-> NO ->(N2O)N-2 at high temperatures. The C-2-additives participate in the oxidation process by introducing additional OH/H/CH3 radicals, thereby facilitating the reactive radical pool and developing the N-C intersystem-crossing pathways. In summary, the extensive multi-speciation data, metrological uncertainty analysis, mechanism validation and development, together with comprehensive kinetic modelling can be valuable resources for further studies of ammonia combustion.

An ultra -rapid Optical Gas Standard (OGS) for absolute NH 3 quantification in the shock tube has been developed. For the first time, the absolute NH 3 mole fractions before the incident shock wave, after the incident shock wave and immediately after the reflected shock wave (within 25 mu s) were quantified using OGS. On that basis, spectrally resolved NH 3 absorption cross-section datasets were measured over pressure ranges of 1.15 - 3.15 bar and elevated temperatures (up to 2680 K), facilitating NH 3 mole fraction quantification after the reflected shock wave using a correlative linear fit method. Besides, comprehensive uncertainty evaluations were conducted for thermodynamic parameters and species mole fraction following the ' Guide to the Expression of Uncertainty in Measurement (GUM) ' . This metrological uncertainty analysis not only contributes to providing high -quality data but also serves as a valuable reference for other traceable measurements in shock tubes, such as dynamic temperature and pressure calibrations.

Hydrogen-fueled argon power cycle engine is a novel concept for high efficiency and zero emissions but suffers from backfire. Water injection has been proven effective in controlling backfire, but the chemical mechanism remains unclear. Therefore, firstly, experimental research on the ignition of hydrogen-oxygen in a shock tube is conducted at typical engine backfire conditions, with diluents of argon or nitrogen, dilution ratios of 79 % and 90 %, equivalence ratios of 1.00, 0.50, and 0.25, at 132 kPa, 909-1579 K. Experimental results show that the ignition delay time is insensitive to the equivalence ratio, diluent ratio, and diluent gases. Secondly, mechanism validation suggests that the collision efficiencies and the pressure dependencies of third-body reactions should be optimized to predict the autoignition better. In this paper, NUIGMech1.3 is recommended for modeling the autoignition at engine-relevant conditions. Thirdly, sensitivity analysis indicates that the reaction R9: H + O-2 = O + OH dominants ignition above 1020 K, while R34a: H + O-2 (+M) = HO2 (+M) dominants below 1020 K. Their competition determines the ignition near 1020 K. Fourthly, the modeling shows that below 1020 K, the high collision efficiency of water considerably increases the net rate of progress of the ignition inhibiting reaction R34a, producing HO2. The consumption of HO2 through HO2 + H = 2OH followed by H-2 + OH = H + H2O results in an overall reaction of 2H(2) + O-2 = 2H(2)O. In contrast, the overall reaction of R9 and other shuffle reactions can be written as a chain-branching reaction of 3H(2) + O-2 = 2H(2)O + 2H. Promoting the ignition retarding reaction R34, along with the inhibiting of the chain-branching reaction, is the chemical kinetic effect of water injection, which helps to control backfire at atmospheric pressure and lower temperature near 950 K.

Ammonia (NH3) holds significant importance as an industrial product, ambient trace pollutant, and a promising zero-carbon energy carrier, underscoring the critical need for accurate quantification in various applications. In this study, a mid-infrared quantum cascade laser (Mid-IR QCL) based tunable diode laser absorption spectroscopy (TDLAS) spectrometer was developed. It was coupled with two reactors, namely a gas cell and a shock tube and operated in three modes: low- and high-frequency (140 Hz and 10 kHz) scan modes and fixed-wavelength mode, tailored to the specific needs of each experimental scenario. The primary objects were NH3 line parameters measurement and absolute NH3 quantification. With the 140 Hz low-frequency scan mode, NH3-Ar pressure broadening coefficients of six transition lines near 1084.6 cm-1 were measured in a gas cell at 295 K and 1-11 mbar for the first time. These coefficients were subsequently employed to quantify the initial NH3 mole fraction in shock tube experiments, considering the substantial adsorption effect of NH3. Using the high-frequency scan mode (10 kHz), spectrally resolved NH3 absorption cross-sections were obtained in a shock tube across a pressure range of 1.46-3.25 bar and a temperature range of 1000-1800 K. This data, acquired for the first time, significantly contributes to the understanding of NH3 behavior in high-temperature environments. Additionally, potential interference from high-temperature water absorption near 1084.6 cm-1 was thoroughly examined. The high-temperature water absorption cross-section was measured over a pressure range of 0.99-3.02 bar and a temperature range of 1322-2905 K, utilizing a near-infrared water laser. Leveraging these comprehensive datasets, the study quantified the NH3 mole fraction during the NH3 oxidation process in the shock tube, employing the fixed-wavelength mode to achieve high time resolution. The quantified NH3 mole fraction was then compared to predictions from eleven recent chemical kinetic mechanisms, demonstrating the utility of the developed spectrometer in validating these mechanisms.