In the present work the experimentally determined values of Landé gJ factors for 20 odd-parity electronic levels of atomic terbium are presented. The Zeeman splitting of the hyperfine structure was investigated using the method of laser induced fluorescence in a hollow cathode discharge lamp in a constant magnetic field. All of the values were determined for the first time, by the analysis of 32 spectral

We present a new VLIDORT-based quasi-spherical vector radiative transfer (RT) model (VLIDORT-QS) that was developed for forward-model simulations of long-path measurements in limb- or nadir-viewing spherical-atmosphere configurations. This paper provides a theoretical description of the RT model, in which the single-scatter radiation field is treated accurately in spherical geometry, while the diffuse

The radiation problem in one-dimensional participating media between two concentric spheres is solved by mapping the concentric spherical domain into the plane-parallel domain, where the radiative rays propagate along curved paths. The computational plane-parallel domain is discretized into slices with constant radiative properties and the angular domain for each control volume is discretized into

In a recent article (Fisher and Rani, Vol. 277, JQSRT, 2022), we presented a narrow band model (NBM) with the absorption coefficient as the fundamental radiative property and applied it to predict radiative heat transfer in one-dimensional (1-D) non-gray enclosures. In this communication, we investigate the accuracy of the NBM in computing radiative transfer in two-dimensional (2-D) non-gray enclosures

The radiative transfer theory with packed media correction (RTT-PM) is a balanced, physically rigorous, and practical light scattering model that is suitable for modeling reflectance and similar spectra of densely packed particulate media. The static structure factor correction to the classical radiative transfer solution and actualization of fundamental particles of media with spheres or aggregates

The NH radical is an extremely important specie in nitrogen chemical reaction networks, in the interstellar medium and atmospheric chemistry. Time resolved Fourier transform spectroscopy technique in the frequency range 10–13 µm has been applied for the measurement of a pure rotational spectrum of the NH free radical (NH) in the ground X3Σ− electronic state. Twelve high N (26–29) triplet-resolved pure

In this article radiative parameters for atomic chromium were determined by a semi-empirical method. The eigenvector amplitudes, determined in our previously published work concerning the hyperfine structure parametrization for even-parity atomic chromium levels, were used. The calculated values of oscillator strengths and lifetimes for low-lying metastable Cr I levels are presented. On the basis of

Using the polarisation labelling spectroscopy, we performed the detailed analysis of the level structure of excited electronic states of the 39KCs molecule in the excitation energy interval between 17500 cm−1 and 18600 cm−1 above the v=0 level of the X1Σ+ ground state. We prove that the observed states are strongly coupled by spin-orbit interaction above 18200 cm−1, as manifested by numerous perturbations

First high-resolution low-temperature spectrum of the 2νOH overtone of trans-formic acid have been measured using direct-absorption laser spectroscopy. The supersonic cooling in the jet expansion to 37 K has dramatically simplified the complex ro-vibrational structure of the band due to the thermal depopulation of higher-lying rotational states. Altogether, 597 lines have been measured with a line-position

Raman scattering in the Earth’s atmosphere is caused predominantly by its most abundant molecular components, N2 and O2. Modeling Raman scattering in the atmosphere is challenging for several reasons: the first challenge is the large number of molecular constants required for the computation of the wavelength/wavenumber shifts due to inelastic scattering by a given molecular species, and the corresponding

The low-lying electronic states correlated to the lowest dissociation limit of SnF+ are investigated using the multireference configuration interaction method including the core-valence correlations and the spin-orbit coupling effects. Based on the computed potential energy curves of the Λ–S and Ω states, the spectroscopic constants of the bound states of SnF+ are determined. The Λ–S components of

The Successive Orders of Scattering (SOS) approach [1] is one of the well known methods for solving the Radiative Transfer (RT) problem. Its efficiency in terms of speed and accuracy of computation was already demonstrated for scattering and absorbing atmospheres in Solar spectrum. Although there are no principle limitations to account for the emission processes, the application of the SOS method for

Tuning surface emissivity has been of great interest in thermal radiation applications, such as thermophotovoltaics and passive radiative cooling. As a low-cost and scalable technique for manufacturing surfaces with desired emissivities, femtosecond laser surface processing (FLSP) has recently drawn enormous attention. Despite the versatility offered by FLSP, there is a knowledge gap in accurately

Line shape effects such as speed-dependence and collisional (Dicke) narrowing are manifest in high signal-to-noise ratio laboratory spectra for a wide range of molecular species and sample conditions. However, these effects are usually neglected in spectroscopic models used in remote sensing of atmospheric greenhouse gases. Here we examine the effects of line profile choice on laboratory spectra and

The Jacobians of particle scattering properties with respect to aspect ratio and effective radius (re) using the invariant imbedding T-matrix method (IITM) are significantly improved by circumventing the divergence of derivatives. The effective radius re is used in three definitions, which are rV, the equal-volume spherical radius, rS, the equal-surface-area spherical radius, and rVS, the ratio of

In this work the hypersonic plasma flow generated by SCIROCCO hypersonic facility has been experimentally characterized as test case, using a high resolved Optical Emission Spectroscopy (OES) during a high enthalpy test campaign. The CIRA methodology to measure roto-translational and NO vibrational temperatures of a free jet via analyses performed in the Ultra Violet spectral range has been improved

Polarimetric studies are an important source of information about the physical properties of celestial bodies. In 2018, we put into operation the new two-channel polarimeters in the Crimean Astrophysical Observatory and the Peak Terskol Observatory. With the help of these instruments, in the period from 2018 to 2020, we carried out measurements of the polarization characteristics of 19 comets. Based

Abstract not available

Multi-temperature models are often used as a simplified way to describe nonequilibrium gases. These models assume Boltzmann distributions within each energy mode, which is useful for reducing the number of parameters in computations. This assumption requires that the energy modes are properly separated (which is valid, for instance, for vibration and rotation in low-lying rovibrational levels of diatomic

SO is found in several astronomical sources such as the atmospheres of Io and Venus. To complete our work on SO line lists, we used our previous fits for v = 0 to v = 6 for the X3Σ- state and v = 0–5 for the a1Δ state [JQSRT 272, 107772 (2021)] for line positions, and high-level ab initio calculations of electric dipole moments for line strengths for the vibration-rotation bands. LeRoy's RKR program

Atmospheric halos are a light scattering phenomenon caused by airborne ice crystals in the atmosphere. Halos can be seen by the naked eye. They provide the observer the information on the kinds of ice crystals present in the sky during a halo display. A combination of ice crystals’ shape, their orientation, and light ray paths through the crystals dictates what halos will be observable. All well-known

Stark broadening is widely used in many research areas, but its applications are limited by the completeness of line width and shift. Based upon the transition line data evaluated by Kramida, we have predicted the Stark broadening parameters of singly ionized carbon by making use of Griem's semiempirical method. The comparison with experimental and theoretical data is conducted and the results presented

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

This paper presents an analysis of data previously reported from a test series in the Electric Arc Shock Tube Facility for incident shocks composed of pure nitrogen. The present work focuses on the lowest velocity measured in the test (approximately 7 km/s) where both molecular and atomic radiation are significant. Analysis of the spectral data with the NEQAIR radiative transport code obtains post-shock

This paper presents an efficient parallel radiative transfer-based inverse-problem solver for time-domain optical tomography. The radiative transfer equation provides a physically accurate model for the transport of photons in biological tissue, but the high computational cost associated with its solution has hindered its use in time-domain optical-tomography and other areas. In this paper this problem

Numerous studies of cometary dust have shown that it has a fairly complex hierarchical structure. At the same time, space missions have provided evidence of solid particles. Computer modeling of light scattering, for which agglomerate debris particles were used, showed that the characteristics of the scattered light strongly depend on the presence of solid particles. We propose a model that makes it

A MARVEL (measured active rotational-vibrational energy levels) analysis of the spectra of vanadium oxide (VO) is performed, involving thirteen electronic states (6 quartets and 7 doublets). 51V16O data from 14 sources are used to form three networks: hyperfine-resolved quartets, hyperfine-unresolved quartets and hyperfine-unresolved doublets. A single quartet network is formed by deperturbing the

The infrared absorption cross sections of pure n-butane, n-pentane, cyclopentane and cyclohexane have been measured in the 3.3 µm region (and 6.8 µm region for cyclopentane) by high resolution Fourier transform spectroscopy. The samples had temperatures of 294 K and 230 K for n-butane, 294 K and 218 K for n-pentane, 296 K and 235 K for cyclopentane, and 294 K and 222 K for cyclohexane. These spectra

The optical properties of non-ideal completely ionized plasma are discussed from the perspective of the kinetic theory approach. It is demonstrated that a physically motivated modification of the Coulomb logarithm, originally proposed in the context of ion-particle scattering in dusty plasma, allows us to improve the theoretical description of the dynamical conductivity and hence of the optical properties

The program FITTER, which has been used successfully for many years to analyze the hyperfine structure in atomic and ionic spectra, has been extended. Confidence intervals for all adjusted parameters are now calculated, adding essential information to the results. A brief overview of the theoretical basics of hyperfine structure is given, the calculation of the confidence intervals is presented and

Obtaining the composition and concentration distribution of combustion products from spectroscopic data often amounts to solving an ill-posed problem, which impairs the accuracy of recovered parameters. This study evaluates the feasibility of using a thermochemical manifold reduction (TCMR) mechanism to reduce the number of unknown parameters, thereby decreasing the ill-posedness of the problem. The

An extension of the parameter space available to the Multiple Sphere T Matrix (MSTM) code is described. The code can now calculate electromagnetic scattering and absorption characteristics of multiple spheres that are placed adjacent to multiple plane boundaries perpendicular to the z direction, with each boundary separating layers of different complex refractive index. The spheres can also form infinitely

An improved modification of the Spectral Approach (SA) used for approximating the nonclassical neutral particle transport equation is described in this work. The term “Spectral” is used to indicate that the nonclassical angular flux is approximated as an expansion in terms of spectral basis functions. In the SA the basis functions are the Laguerre polynomials. The main focus of the modified SA lies

The problem of absorption of diffuse light by a 2D array of identical spherical particles is considered. The equations to solve this problem are derived on the basis of statistical approach. They can be used to match parameters of the array and the illumination system to get maximum absorption. The numerical results are presented for absorption coefficients of arrays with the imperfect triangular lattice

Improved energy levels for singly ionized and neutral zirconium of both even and odd parity are determined from Fourier Transform Spectrometer data using a least-squares optimization procedure. Data from interferometric spectrometers provides much tighter control of systematic uncertainties in line position measurements than was achieved using older (e.g. Rowland Circle) dispersive spectrometers.

We consider systems consisting of multiple plates, where the dynamics of the positions and the temperatures of the plates is determined by the non-equilibrium Casimir forces and the heat transfer between them, respectively. We numerically and theoretically show that in these systems, the temporal dependence of the position of a plate can be made to conform to a prescribed trajectory through a feedback

In this study, a method for using arrays of mesoscale structures to modify the apparent optical properties of an opaque composite surface has been theoretically demonstrated to both raise and lower the apparent emissivity as compared to the intrinsic properties of the constitutive materials. For design problems where thermomechanical and optical material properties are both of importance, mesoscale

The paper presents a tool for numerical simulation of the backscatter amplification effect associated with double-pass propagation of laser radiation passing through an anisotropic non-Kolmogorov turbulence. It is shown that for variety of power-law exponents of refractive-index fluctuations, all other conditions being equal, the value of amplification factor also changes: the amplification factor

Accurately measuring the spectral emissivity is of significant importance in thermal radiation. In this study, an improved measurement method for determination of spectral emissivity via modulating the surrounding radiation is proposed. A proof-of-concept measuring apparatus is constructed, and the main component parts are described in detail. The temperature uniformity of the isothermal aperture is

Based on the adjoint boundary value problem proposed decades ago by Zulehner and Rohatschek [1], analytic and closed-form expressions for the photophoretic forces exerted by arbitrary-shaped beams on homogeneous and low-loss spherical particles is derived in both the free molecular and slip flow regimes. To do so, the asymmetry vector for arbitrary refractive index particles is explicitly calculated

Optical spectra of Fe-like Mo16+ and Mn-like Mo17+ ions were measured using the newly developed low-energy electron-beam ion trap at Fudan University. The observed emission spectra incorporated six lines from Mo16+ ions and five lines from Mo17+ ions. These eleven lines included ten lines that were measured for the first time. Spectra modeling was carried out based on the collisional-radiative (CR)

In the emission spectrum of the 12C17O+ isotopologue the Comet-Tail (A2Πi→X2Σ+) system has been observed and analysed for the first time. 1215 spectral transitions in the 16 950 to 22 000 cm−1 region, belonging to three A−X (1−0,1−1 and 1−2) bands, were recorded with the Fourier-transform spectrometer and measured with an accuracy of 0.01 cm−1. As a result of analysis, 15 molecular parameters of the

Calculations of the N2-, O2-, and air-broadened widths, together with their temperature dependence exponents have been made for transitions of CH3I in the ν5 and ν6 bands. The calculations are based on a semi-classical line shape formalism developed by the current authors through modifying and refining the Robert-Bonamy formalism. In recent years, we have applied this formalism for linear molecules

The high resolution infrared spectra of CD4 were measured with a Bruker IFS125 HR Fourier transform infrared spectrometer at an optical resolution of 0.003 cm−1 and analyzed in the region of 800–1400 cm−1 where the ν2/ν4 dyad is located. The number of 3633 and 1927 transitions with Jmax=31 and Jmax=28 were assigned to the ν4 and ν2 bands of CD4 (which is more than three times higher in comparison with

A non-equilibrium mid-infrared black phosphorus (BP) light emitter and absorber for a thermophotonic (TPX) system was investigated in this study. A fluctuational electromagnetic simulation was performed to evaluate the non-equilibrium spectral energy fluxes from the bulk BP and between the bulk BPs, and the calculated spectral energy flux of the BP emitter exceeded the blackbody limit. The underlying

In the present work Landé gJ factors for 17 even-parity electronic levels of the terbium atom are presented. The spectra of the Zeeman splitting of the hyperfine structure were recorded with the method of laser spectroscopy in a hollow cathode discharge lamp in a constant magnetic field, with laser induced fluorescence detection. The analysis of 47 spectral lines of terbium in the spectral range between

Accurate knowledge of the line parameters of ammonia (NH3) transitions is important for developing precise laser-based NH3 sensors. We report the measurement of line-strengths and temperature-dependent broadening coefficients of NH3 with N2, air, Ar, and CO2 for six transitions in the ν2 fundamental band near 1103 cm−1. The absorption feature contributed by the target transitions is of particular interest

The Community Radiative Transfer Model (CRTM) is a powerful and versatile scalar radiative transfer model for satellite data assimilation and remote sensing applications. It is implemented as an object-oriented Fortran library, enabling flexible code development and optimal runtime performance on clusters. The downsides of the Fortran interface are a steep learning curve for students and the reduced

The 12CO2 band at 1.6 µm is used for carbon dioxide monitoring in the Earth atmosphere. The targeted accuracy of these measurements motivates important efforts to improve the quality of the spectroscopic parameters in atmospheric conditions. In the present work, the line shapes of the R(6), R(12), R(16), R(18) and R(20) transitions of the 30013-00001 band of 12CO2 in air are studied with a cavity ring

Current operational optical satellite-based Earth observation methods targeting at vegetation are optimised for the high- and medium-resolution satellites with pixels sizes starting at ten meters. This resolution is coarser than the typical size of a vegetation structural element, such as a tree crown, and much coarser that of scattering elements, such as leaves. For this reason, vegetation can be

We use a Fourier transform spectrometer based on a difference frequency generation optical frequency comb to measure high-resolution, low-pressure, room-temperature spectra of methane in the 1250 – 1380-cm−1 range. From these spectra, we retrieve line positions and intensities of 678 lines of two isotopologues: 157 lines from the 12CH4 ν4 fundamental band, 131 lines from the 13CH4 ν4 fundamental band

Tunable diode laser absorption spectroscopy is used for recording the spectrally mixed profiles of argon 772.376 nm (2p7-1s5) and 772.421 nm (2p2-1s3) lines at different argon background pressures between 0.3 and 1 atmosphere. The absorbing atoms in the Ar*(1s5) and Ar*(1s3) metastable states are produced in a plane-to-plane dielectric barrier glow discharge operating at 20 kHz. The pressure broadening

The radiative transfer equation (RTE) is an integro-differential equation and solving it is time-consuming except in a few specific cases. A fast method based on dynamic mode decomposition (DMD) is introduced for solving the RTE in an absorbing-emitting and scattering medium. First, some parameters are considered as independent variables. The RTE is solved for different values of these parameters (known