Search

The effect of two factors, i.e., the dependence of the broadening coefficients γ and shifting coefficient δ on the speed of absorbing water vapor molecule (wind effect) and a change in the H2O molecule speed upon collision with gas atoms, on the profile of an absorption line of water vapor in a mixture with helium, argon, krypton, and xenon is studied with three absorption lines of H2O molecule from ν1 + ν2 + ν3 band with different rotational quantum numbers of the initial quantum state. The wind effect is shown to be the strongest in interactions of H2O molecules with argon, krypton, and xenon atoms. The results can be used in the analysis of absorption spectra of water vapor mixed with monatomic gases. [ABSTRACT FROM AUTHOR]

In order to investigate the time variations and the peculiarities of the optical spectra of the RV Tauri star R Sct, high-resolution spectroscopic observations in the wavelength interval around the line (6540–6580 Å) were obtained between 2014 and 2018. The phase dependence of the equivalent widths and radial velocities was measured for the and Fe I 5669.224 Å lines, respectively. shows considerable changes in its line profile. We observed double-peaked emission and an inverse P Cygni profile in this line. We detected a variation from inverse P Cygni to P Cygni profile for both Ti I 6554.239 Å and Ca I 6572.797 Å lines at phases where the shock wave is propagating through the atmospheric layer in which the Hα lines are forming, particularly around which is just after the deep minimum and , just after shallow minimum. An increase in the shock wave velocity generates a decrease in the intensity, which is explained by the ionization phenomenon. The detailed description of the variations in R Sct reveals its important properties. The observation of the P Cygni and the inverse P Cygni profile indicate that expanding and infalling layers are simultaneously present in the stellar atmosphere, pointing out the complicated nature of this object. [ABSTRACT FROM AUTHOR]

We analytically obtained the frequency dependences of the absorption coefficient profile, taking into account the combined influence of the macroscopic motion of matter, Doppler and Voigt mechanisms of spectral line broadening. The effect of rotation of a spherical plasma on the formation of resonant fluorescence by barium ions upon absorption of laser radiation at a wavelength of 455.4 nm was studied. The deformation of the frequency shape of the laser radiation passing through the plasma and the emission spectrum is due to a shift in the absorption coefficient profile and its broadening caused by the rotational motion of the plasma. An increase in the resonant photons escape from the medium stipulated by the broadening of the emission spectrum of the resonance line is predicted. [ABSTRACT FROM AUTHOR]

The qualitative and quantitative effects on the line profile of hard and soft velocity-changing large- and small-angle scattering collisions of absorbing molecules, respectively, are considered. It is shown that large-angle scattering significantly contributes to the diffusion profile model, known as the "soft" collision model, as compared to that in the hard collision model. The difference between these traditional models lies only in the mathematical representation of the collision integral, either in integral or differential form, and the following analytical expressions for the profiles. Simple approximate formulas for the profile are derived and tested, which simultaneously take into account hard and soft collisions. [ABSTRACT FROM AUTHOR]

An algebraic approximation has been obtained for a spectral line profile derived with allowance for collisions with scattering both at large and small angles. In the region of practically significant parameters, deviations of the approximate profile from the exact calculation do not exceed a tenth of a percent. It is shown that soft collisions with scattering at classical small angles reduce the effect of the collisional narrowing of lines owing to which the line profile becomes flatter as compared to the profile in the model of hard speedrelated collisions. The relative difference between maximum amplitudes of these profiles can reach 15%, which leads to the necessity to take into account soft collisions together with hard collisions in the quantitative processing of high-resolution spectra under conditions of nonuniform broadening of the lines. [ABSTRACT FROM AUTHOR]

line profile of fluorescent intensities in confocal images is frequently examined. We have developed the computer software tool to analyse the profiles of intensities of fluorescent probes in confocal images. The software averages neighbouring pixels, adjacent to the central line, without reducing the spatial resolution of the image. As an experimental model, we have used the skeletal muscle fibre isolated from the rat skeletal muscle extensor digitorum brevis. As a marker of myofibrils' structure, we have used phalloidin-rhodamine staining and the anti-TIM antibody to label mitochondria. We also tested the distribution of the protein kinase B/Akt. Since signalling is ordered in modules and large protein complexes appear to direct signalling to organelles and regulate specific physiological functions, a software tool to analyse such complexes in fluorescent confocal images is required. The software displays the image, and the user defines the line for analysis. The image is rotated by the angle of the line. The line profile is calculated by averaging one dimension of the cropped rotated image matrix. The spatial resolution in averaged line profile is not decreased compared with single-pixel line profile, which was confirmed by the discrete Fourier transform computed with a fast Fourier transform algorithm. We conclude that the custom software tool presented here is a useful tool to analyse line profiles of fluorescence intensities in confocal images. [ABSTRACT FROM AUTHOR]

The comae of very active comets have a substantiallymore complex coma than their weaker cousins.The primary cause of this is photolytic heating and collisionsthat occur over an ever-larger volume of the coma asQH2O increases. Collisionswith the photochemical daughters ofwater in this regionmodify the radial distributions and outflowvelocity of each species, excite and quench metastableemissions, and introduce velocity gradients from photolyticheating. Comet Hale–Bopp was the first comet forwhich the collisional coma was both spatially resolvableand comparable in extent to the scale lengths ofmajor coma species. In the case of this object,the classical assumptions that make it possible toinvert radial emission line profiles, brightnesses, andlineshapes to production rate and velocity eitherdo not hold or require adjustment to work.Here we describe how a large collision zone modifies thecoma, how it affects the classical methods for obtainingproduction rate and velocity, and discuss how wide fieldimaging may be combined with modified versions ofsimple models to address the complications and extract somestructural information. [ABSTRACT FROM AUTHOR]

A review of the application, during the years 1980 to 2000, of the modified semiempirical method developed by Dimitrijević and Konević in 1980 for calculating the parameters of Stark broadening is given and the possibility of using this method to calculate the Stark width and, in some cases, the shift of a large number of spectral lines of various atoms and a number of ions is shown. [ABSTRACT FROM AUTHOR]