Measured Line Intensities Research Articles

Measurements of line parameters for 12C16O2 near λ = 1.05 μm by cavity ring-down spectrometer

The absorption spectra of 12C16O2 within the wavenumber range of 9358–9648 cm−1 have been precisely measured using a continuous-wave cavity ring-down spectrometer at room temperature. Employing synthetic gas mixtures comprising carbon dioxide, nitrogen, and argon, the line parameters, including line intensities and self-, N2- and Ar- broadening coefficients have been retrieved in the 2003r-00001 (r = 1,2,3) bands. This retrieval process was facilitated by a multi-spectral fitting program that utilizes Voigt line profiles. A comparative analysis of our measured line intensities and self-broadening coefficients with those present in established databases, such as HITRAN2020, CDSD296, AMES-2021, and HITEMP2010, has been conducted. The line intensities and self-broadening coefficients for 12C16O2 deviate by an average of less than 1 % from the values reported in the HITRAN2020 database. The J-dependence of N2- and Ar- broadening coefficients has been investigated by comparing this work with experimental results and theoretical predictions from other vibrational bands. This research offers important experimental references for the improvement of computational models and the exploration of Venus and Mars.

He II line intensity measurements in the JET tokamak

Abstract An understanding of the behaviour of the D or He fuel used in tokamak discharges is essential in analyses such as modelling edge and divertor transport and the erosion of the vessel walls. However, poor agreement is found between measurements made on the JET tokamak and collisional-radiative models used to predict the hydrogen-like D and He line intensities. The range of temperatures of the plasmas emitting the radiation is also limited, in contrast to that for many impurities for which a wide range is possible. This is particularly so for He II whose line intensities tend to have the same near-constant ratios in most pulses, suggesting that the emission originates in plasma regions with very similar electron temperatures. To gain understanding and to allow quantitative comparisons with theoretical models, extensive observations of the VUV Lyman series have been made, for all discharge scenarios run during three He campaigns. Those for He discharges in both JET ITER-like wall (JET-ILW) and JET C (JET-C) campaigns are presented here. He discharges have the advantage of fewer impurities resulting in less complex spectra than when D is used as the fuel. However, the characteristics of the observed discrepancies are similar in both species, allowing He to be used as a proxy for D in order to gain understanding of the discrepancy. In addition, the study of He avoids the complication of molecular species contributing to the level populations. Opacity effects are also expected to be less severe in He discharges. Nevertheless, so as to ensure that the measurements are not unduly affected by opacity, comparisons have also been made with emission from Balmer and Paschen series members. Measurements of both line intensities and their ratios are presented for all-pulse surveys and for individual pulses. In exceptional cases in which the He emission is intense a dependence on the He II line intensity is demonstrated. The discrepancy between these measurements and the theoretical models is illustrated.

Assignment and modeling of 13CH4 spectrum at 298 K in the lower part of the Tetradecad in the 4970–5300 cm−1 range

The absorption spectrum of the 13CH4 methane isotopologue was recorded on a Bruker IFS-125HR Fourier transform spectrometer at 298 K in the 4970–6200 cm−1 range. In this paper we report the results of assignment and modelling of the line positions and intensities of 13CH4 in the range of weaker absorption between 4970 and 5300 cm−1, corresponding to the lower part of Tetradecad, dominated by the 4ν4 band system near 5180 cm−1. The empirical list in this spectral range contains 1642 lines. Using an effective Hamiltonian initially derived from the analyses of cold Fourier transform (4970–5853 cm−1) and laser direct absorption (5853–6200 cm−1) spectra of the 13CH4, we assigned 1600 lines belonging to four bands of the Tetradecad up to Jmax=16. The 1548 line positions were fitted with an rms deviation of 1.7 × 10−3 cm−1. Measured line intensities were modeled for 674 transitions using the effective dipole transition moments to an rms deviation of about 7 %. The new data were used for the simultaneous global fit of the 13CH4 Hamiltonian parameters for the {Ground state / Dyad / Pentad / Octad / Tetradecad} system and the dipole moment parameters for the {Ground state - Tetradecad} system.

NH3 line broadening coefficients and intensities measurement and impurities determination in emerging applications: CCUS, Biomethane and H2

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 (NH3) absorption spectroscopic parameters and determine NH3 impurities toward three emerging applications. We for the first time measured the pressure broadening coefficients perturbed by Air, O2, N2, He, CO2, CH4, and H2 and the line intensities of six NH3 transition lines near 1084.6 cm−1. The measured NH3-He, NH3-Air, and NH3-CO2 broadening coefficients align with HITRAN database, while NH3-H2 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 NH3 impurity requirements outlined in CCUS (ISO 27913:2016), Biomethane (EN 16723:2016), and H2 (ISO 14687:2019) standards. Based on the concept of optical gas standard (OGS), the NH3 impurity detection requirements in all three standards have been fulfilled with an uncertainty of 1.35 %. The precision of the NH3-OGS is 800 part per trillion (ppt) with an integration time of 100 s. The repeatability of the NH3-OGS is 130 ppt for a continuous measurement time of 48 min. Notably, the NH3-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.

Abstract B004: Investigating loss of ARID1A protein on endometrial cancer progression through the destabilization of adherens junctions

Abstract The purpose of this work is to test the hypothesis that loss of ARID1A promotes endometrial cancer progression by destabilizing tumor cell adherens junctions proteins. ARID1A, an important structural subunit of the SWI/SNF chromatin remodeling complex, is mutated in 26-39% of endometrioid tumors. In endometrial cancer loss of ARID1A has been classically linked to loss of ARID1A expression and has been shown to correlate with increasing tumor grade. However, little is known about the functional impact of ARID1A loss on endometrial cancer progression. A common hallmark of aggressive endometrial cancer is decreased membranous expression of adherens junction proteins, E-Cadherin and β-Catenin. In colorectal and gastric cancer loss of ARID1A expression has been shown to directly downregulate E-Cadherin expression. To determine how loss of ARID1A affects adherens junctions and its impact on endometrial cancer progression we utilized human endometrial cancers and human endometrial cancer cell lines. Using immunohistochemistry, we determined the expression and localization of ARID1A and the adherens junction protein β-Catenin in forty-six human endometrioid type endometrial cancers. Intratumoral heterogeneity of ARID1A expression allowed for quantification of membranous E-Cadherin in relation to presence or absence of ARID1A protein within the same human endometrial tumor. To quantify membranous E-Cadherin we performed immunofluorescence and used line intensity measurements in intratumoral areas of ARID1A presence and ARID1A absence. To assess effects of ARID1A loss on adherens junction in vitro we used short-hairpin RNA to acutely knockdown ARID1A in the endometrial cancer cell lines Ishikawa and ECC-1. Protein expression of ARID1A and E-Cadherin in ARID1A knockdown cells was assessed by Western Blot. Within our cohort of forty-six human endometrial tumors, 75% of tumors with wild-type ARID1A and 45% of tumors with mutated ARID1A had absence of ARID1A protein expression. Due to the discordance between presence of an ARID1A gene mutation and the expression of ARID1A protein, we hypothesize that there are alternative mechanisms of ARID1A protein regulation in endometrial cancer. Additionally, tumors with loss of ARID1A show a trend towards nuclear localization of β-Catenin and have a significant decrease in membranous E-Cadherin expression (P<0.001). However, acute knockdown of ARID1A in Ishikawa and ECC-1 human endometrial cancer cells does not affect total E-Cadherin protein. This suggests that loss of ARID1A may decrease adherens junction stability, as decreased membranous expression of E-Cadherin without total protein change is a common phenotype of destabilized adherens junctions. Thus, we hypothesize that loss of ARID1A destabilizes adherens junctions leading to increased endometrial tumor aggression. Citation Format: Savannah E. Wright, Isurika Weerasinghe, Russell R. Broaddus, Andrew B. Gladden. Investigating loss of ARID1A protein on endometrial cancer progression through the destabilization of adherens junctions [abstract]. In: Proceedings of the AACR Special Conference on Endometrial Cancer: Transforming Care through Science; 2023 Nov 16-18; Boston, Massachusetts. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(5_Suppl):Abstract nr B004.

New acetylene line list near 3.8-μm - Part III - 12C13CH2 and 12C2HD

The intensities of minor acetylene isotopologues 12C13CH2 and 12C2HD have been studied from Fourier transform spectra of acetylene in natural abundance using high optical path length. This study completes the work performed in the two first paper of the series (JQSRT 2023;295:108,413 and JQSRT 2023;311:108,771) where 71 bands of 12C2H2 were studied in the ΔP = 4 spectral region (∼2400–2900 cm−1). In this work, 692 measured line intensities allowed to derive vibrational transition dipole moment squared (and sometimes Herman-Wallis coefficients) for 11 bands of 12C13CH2 and 6 bands of 12C2HD. Using line positions and broadening parameters from literature, a line list has been generated for atmospheric and astrophysical applications.

Laboratory Measurement of CH2DOH Line Intensities in the Millimeter-wave Region

Deuterium fractionation in molecules is known as one of the most powerful tools to study chemical processes during star and planet formation. Among various interstellar molecules, methanol often shows very high deuterium fractionation. It is the most abundant saturated organic molecule and is known as a parent species to form more complex organic molecules. However, deriving the abundance of deuterated methanol suffers from the uncertainty in the intrinsic line intensities (S μ 2) of CH3OH isotopologues. Due to their floppy nature, theoretical evaluation of the S μ 2 values is not straightforward, particularly for asymmetric-top asymmetric-frame isotopologues such as CH2DOH. In this study, we have measured the line frequencies and their intensities for CH2DOH in the millimeter-wave region from 216 to 264 GHz by using an emission-type millimeter and submillimeter-wave spectrometer. For the a-type J = 5 − 4 transition, the derived S μ 2 values are 13%–27% larger than those theoretically calculated, except for the transitions of K a = 2 for e 0 and K a = 1 for e 1 affected by avoided level crossing. For b-type transitions, significant systematic differences are found between theoretical and experimental S μ 2 values. The results of the present study enable us to accurately derive from observations the CH2DOH abundances, which are essential for understanding deuterium fractionation in various sources.

The first observation of the 12C16O2 absorption bands near 660 nm

The absorption spectra of carbon dioxide were recorded in the region from 15,000 to 15,300 cm−1, using a Bruker IFS 125 HR Fourier transform spectrometer and a 30 m multipass cell with the White type optical system. The recording was performed at a spectral resolution of 0.044 – 0.050 cm−1, room temperature, a path length of 1057.95 m and pressures of 185 and 362 mbar. Utilization of a LED as a light source provided a sensitivity (noise equivalent absorption) at the level of kν = 1.23 × 10-10 cm−1 and allowed detection of a number of lines of two 3005i − 00001 (i = 2,3) bands and several lines of the 60031 – 00001 band of 12C16O2 with the intensity values down to 10-30 cm−1/(molecule cm−2) at 296 K. These bands were observed for the first time. The uncertainty of the line position measurements was estimated to be about 0.005 cm−1 for the unblended lines with a high signal-to-noise ratio. The uncertainties of the retrieved line intensities for the strongest unblended lines are at the level of 15 %. The spectroscopic constants for observed bands were fitted to the observed line positions. The vibrational transition dipole moments squared of these bands were fitted to the observed line intensities. The measured line positions were compared to those from the HITRAN2020 database and to those predicted with the global effective Hamiltonian. The measured line intensities were compared to the values from the HITRAN2020 database and from the Ames2021 line list.

Line Position and Line Intensity Modelings of H218O up to the First Triad and J = 20

Line position and line intensity analyses are carried out for the H218O isotopic species of the water molecule. Both datasets involve the five lowest lying vibrational states. For the line position analysis, the dataset includes infrared and far infrared transitions recorded in this work using high-temperature Fourier transform emission spectroscopy. Also included are already published infrared, far infrared, microwave, terahertz, Doppler-free combination differences, and kHz accuracy lines. The fitting is carried out with the bending–rotation approach and allows us to reproduce 12 858 line positions involving levels with J ≤ 20 and Ka ≤ 18, with a unitless standard deviation of 1.9, varying 207 spectroscopic parameters. For the line intensity analysis, far infrared line intensities measured in this work using Fourier transform spectroscopy in addition to previously measured line intensities are fitted. 5612 line intensities are accounted for with a unitless standard deviation of 1.5. The results from both analyses are used to build a line list for atmospherical purposes, spanning the 2–5000 cm−1 spectral range and containing 7593 lines. This line list and calculated energies and line intensities are compared to those already published.

The absorption bands of 12C16O2 near 718 nm

The absorption spectra of carbon dioxide were recorded in the region from 13,500 to 14,200 cm−1, using a Bruker IFS 125 HR Fourier transform spectrometer and a 30 m multipass cell with the White type optical system. The recording was performed at spectral resolution of 0.03–0.04 cm−1, room temperature, path length of 1057.95 m and at three pressures of 252, 403 and 582 mbar. The achieved sensitivity (noise equivalent absorption) at the level of kν = 6 × 10−10 cm−1 allowed detection of a number of lines of three 2005i - 00001 (i = 1,2,3) bands of 12C16O2 with the intensity values down to 10−29 cm−1/(molecule cm−2) at 296 K. The 20053–00001 band was observed for the first time. The line intensities for all bands were measured for the first time. The uncertainty of the line position measurements was estimated to be about 0.007 cm−1 for the unblended lines with a high value of the signal-to-noise ratio. The uncertainties of the retrieved line intensities for the strongest unblended lines are on the level of 10%. The spectroscopic constants for the three observed bands were fitted to the observed line positions. The vibrational transition dipole moments squared of these bands were fitted to the observed line intensities. A comparison of the measured line positions to those from the HITRAN2020 database was done. Finally a comparison of the measured line intensities to those contained in the HITRAN2020 database as well as in the new version of the Ames line list was also given.

Pedestal particle balance studies in JET-ILW H-mode plasmas

JET-ILW type I ELMy H-modes at 2.5 MA/2.8 T with constant NBI heating (23 MW) and gas fuelling rate were performed, utilising edge localised mode (ELM) pacing by vertical kicks and plasma shaping (triangularity, δ) as tools to disentangle the effects of ELMs, inter-ELM transport and edge stability on the pedestal particle balance. In agreement with previous studies, the pedestal confinement improves with increasing δ, mostly due to a significant increase in pedestal density while the ELM frequency () is decreased. Improved pedestal confinement with increasing δ was observed even when the pedestal MHD stability was degraded artificially by vertical kicks, implying that increased triangularity may favourably affect the inter-ELM pedestal recovery. The workflow developed to quantify the pedestal particle balance uses high time-resolution profile reflectometry to characterise the inter-ELM evolution of the plasma particle content (), the NEO drift-kinetic solver to evaluate the neoclassical fluxes and interpretative EDGE2D-EIRENE simulations to estimate the edge particle source. The edge particle source is then constrained by deuterium Balmer-α line intensity measurements in the main chamber, which are, however, strongly affected by reflections from the metal walls. The reflections are accounted for by the CHERAB code taking the divertor emission (the brightest light source in the torus) distribution from imaging spectroscopy measurements as input. Our analysis shows that in the second half of the ELM cycle, the volume-integrated particle source is larger than , indicating that transport plays a key role in the inter-ELM pedestal recovery.

Measurement of self-broadening coefficients and line intensities of ν1 + ν3 + ν4 ‒ ν4 band of acetylene in 1.5 μm spectral region: External cavity diode laser based absorption study

Acetylene is considered to be an important molecule for spectroscopic research due to its role in environmental chemistry, astrophysics, biochemistry and photochemistry of various planets. The high resolution spectroscopic studies of acetylene (12C2H2) in the 6474–6515 cm−1 spectral range have been performed using in-house developed external-cavity diode laser absorption spectroscopy technique. The study is focused on experimental measurement of self-broadening coefficients (γself) and line intensities of 27 l-doublet ro-vibrational lines belonging to the P-branch transition of ν1 + ν3 + ν4 ‒ ν4 hot band lying in the 6474–6515 cm−1 spectral range. The γself and line intensity have been retrieved by modelling of each experimentally observed rotational line with standard Voigt line profile using custom written python based computer program. The measured γself and line intensities were compared with the values present in HITRAN2020 database, showing mean difference of about -1.9% and 2.48%, respectively. In contrast to the line intensity, where rotational and symmetry dependency are readily visible, γself exhibits only rotational dependency. The l-type doubling constants of both ν1 + ν3 + ν4 and ν4 states of ν1 + ν3 + ν4 ‒ ν4 hot band have also been obtained. Detailed understanding of these molecular parameters will play an important role in modelling of planetary atmospheres.

Pressure dependence of the measured line intensity and super-Lorentzian effects in the absorption spectra of pure HCl.

Super-Lorentzian effects in the troughs between lines and the pressure dependence of the line intensities retrieved from fits of absorption spectra of pure HCl have been investigated both experimentally and theoretically. For that, spectra of pure HCl gas in the 2-0 band were recorded with a Fourier Transform spectrometer at room temperature and for pressures ranging from 1 to 10 atm. The line intensities, retrieved from fits of the measurements with the Voigt profile using a single spectrum fitting technique, reveal large decreases with increasing pressure - up to 3% per atm - with a relatively weak rotational dependence. We also show that the absorptions in-between successive P and R transitions are significantly larger than those predicted using Voigt profiles. Requantized classical molecular dynamics simulations were made in order to predict absorption spectra of pure HCl matching the experimental conditions. The pressure dependence of the intensities retrieved from the calculated spectra as well as the predicted super-Lorentzian behavior between lines are in good agreement with the measurements. Our analysis shows that these effects are essentially due to incomplete collisions, which govern the dipole auto-correlation function at very short times.

Pure rotational R(0) and R(1) lines of CO in Ar baths: experimental broadening, shifting and mixing parameters in a wide pressure range versus ab initio calculations.

The results of a rigorous study of the two first pure rotational transitions of CO perturbed by Ar are presented. The experimental part is based on the use of three different spectrometers covering together the pressure range from 0.02 up to 1500 torr. The measurement results of collisional line shape parameters are supported by fully ab initio calculations, which are in remarkable agreement with retrieved data. A sub-percent uncertainty of line intensity measurements is achieved and the first firm evidence that the resonance spectrum of CO is observed on the continual pedestal is given. We analyze the results of our ab initio calculations on the basis of early analytical theories and demonstrate a good general applicability of the latter to the CO-Ar collisional system.

Near-infrared detection and line intensity measurements of H2S with ECDL source based off-axis integrated cavity output spectroscopy

Hydrogen sulphide (H2S) is an extremely hazardous gas which leads to poisoning at higher concentration. Here, we demonstrate the trace detection and line intensity measurement of H2S by means of efficient and indigenously developed off–axis integrated cavity output spectroscopy (OA-ICOS) technique coupled with an external cavity diode laser operating in near-infrared spectral region. Trace detection of H2S was made with OA-ICOS absorbance spectra of ro-vibrational line (51, 5 → 61, 6 & 50, 5 → 60, 6) centered at ∼ 6344 cm−1 of ν1 + ν2 + ν3 band. A ∼ 600 ppbv limit of detection was achieved for an averaging time of 350 s with Allan deviation analysis. Additionally, line intensities of several degenerate R branch transitions of ν1 + ν2 + ν3 band including 51, 5 → 61, 6 & 50, 5 → 60, 6 transition was experimentally measured with OA-ICOS. The study will be valuable in aiding the spectroscopic databases of H2S and have potential application in extracting molecular concentrations in the planet’s atmospheres.

High sensitivity absorption spectroscopy of hydrogen chloride near 770nm

The Cavity Ring-Down Spectra (CRDS) of hydrogen chloride were recorded in the 12,943–13,295 cm−1 region with sensitivity of 4 × 10−11 cm−1. The lines P(4) – P(12) of the 5–0 band of two H35Cl and H37Cl isotopologues were assigned in these spectra. The positions, intensities, self-broadening and self-pressure-induced shift coefficients of these lines were measured. The measured line positions are in a good agreement with those presented in the HITRAN2020 database. The measured line intensities are 1.3 times greater than those from the HITRAN2020 database. The measured self-broadening coefficients are in a good agreement with the HITRAN2020 values for the small angular momentum quantum numbers and slightly exceed the HITRAN2020 values for the large angular momentum quantum numbers.

Baseline-free direct absorption spectroscopy and its application in line intensity measurement of ammonia

A method based on direct absorption spectroscopy (DAS) without baseline fitting procedure, which we called baseline-free DAS (BFDAS), is proposed. The BFDAS utilizes three transmission spectra at different pressures and a simulated absorbance at the smallest pressure to derive the difference of integral absorbances at the other two pressures, where gas concentration or line intensity can be obtained. The proposed method is experimentally validated by comparing the line intensities of ammonia measured by conventional DAS and BFDAS, which demonstrates good performance of the BFDAS in broadened or narrowly scanned spectra where baseline fitting is difficult to be implemented.

The ν3 band of 16O14N18O: Line positions and intensities

The Fourier transform IR spectra of samples prepared by mixing two gaseous species 18O2/14N16O (1:2) have been recorded in the region of the ν3 band of nitrogen dioxide. The spectra contain the lines corresponding to the ν3 band of the 16O14N18O isotopologue within the 1540–1640 cm−1. In total 1795 lines of the ν3 band of this isotopologue were assigned with the rotational quantum numbers N and Ka up to 51 and 12, respectively, what corresponds to 3487 electron spin-rotation-vibration transitions. The overall measured set of the line positions was used to fit the effective Hamiltonian parameters. The fitted set of the parameters reproduces the observed line positions with an rms of 3.6 × 10−3 cm−1. A selected set of the measured line intensities was used to determine the effective dipole moment parameters describing the line intensities of the ν3 band. The rms deviation of the fit is 5.0%. It was found that the lines with the ΔKa = ±1 are very weak compared to those with the ΔKa =0. At attained sensitivity only few lines with the ΔKa = ±1 were assigned. The measured line intensities lead to the small value of the dipole moment derivatives ratio |(∂μx/∂q3)(∂μz/∂q3)|≈0.139.

Apparent change of the 3C/3D line intensity ratio in neonlike ions.

The resonance 3C ([(2p5)1/23d3/2]J=1 → [2p6]J=0) to intercombination 3D ([(2p5)3/23d5/2]J=1 → [2p6]J=0) line intensity ratio of neonlike ions has been studied. The measured line intensity ratio for neonlike Xe44+ ions shows an apparent change, which is reproduced by the calculations using the relativistic configuration interaction plus many-body perturbation theory. It is clearly elucidated that the change in the 3C/3D line intensity ratio is caused by strong configuration mixing between the upper levels of the 3D and 3F ([(2p5)1/23s]J=1 → [2p6]J=0) lines. The present measurement allows us to discuss the 3C/3D line intensity ratio for the highest-Z ions hitherto, which suggests that the experiment-theory discrepancy in the 3C/3D line intensity ratio of neonlike ions diminishes with increasing atomic number Z and further trends to vanish at higher-Z ions. Furthermore, the present study provides benefits to better understand configuration mixing effect in the radiative opacity of hot plasmas.

Insights from Collisional-Radiative Models of Neutral and Singly Ionized Xenon in Hall Thrusters

Collisional-radiative (CR) models for neutral and singly ionized xenon have been constructed for applications to Hall thruster diagnostics. The models use primarily theoretical electron-impact excitation cross sections calculated using the Dirac B-spline R-matrix method. This paper describes the models’ construction and their validation against heritage CR models and previously published Hall thruster data, and then outlines several applications. The baseline 0D steady-state models are used to investigate electron density dependence in neutral xenon emission line intensity ratios commonly used to measure electron temperature, and also to demonstrate that stepwise ionization through excited states is an important process in Hall thrusters. The models are extended to evaluate impacts of neutral and ion transport on 0D CR model applicability, intrinsic bandwidth limits for time-dependent line intensity measurements, and errors introduced when the plasma is assumed to be optically thin.