arXiv subjects

B. P. Lavrov

Publications and source records attributed to B. P. Lavrov.

17 recordsLinked to original sources

arXiv2015

Tables of Einstein coefficients and lifetimes of upper rovibronic levels for Q-branch lines of the the $d^3Π_u^- - a^3Σ_g^+$ bands for the $H_2$, HD, $D_2$, and $T_2$ molecules

The present work reports results of the semi-empirical determination of the spontaneous emission transition probabilities (Einstein coefficients) for Q-branch lines of Fulcher-$α$ band system and radiative lifetimes of upper electronic-vibro-rotational (rovibronic) levels for the most important isotopologues of diatomic hydrogen. They are based on an adiabatic theoretical model and all currently available experimental data on rovibronic energy levels, ratios of the line strengths and the lifetimes. Numerical data are presented in tabular format for vibrational quantum numbers v=0-7 (N is the quantum number of total angular momentum of the molecule excluding electron and nuclear spins). The uncertainties (one SD) of experimental and semi-empirical data are listed for each datum. Currently available results of ab initio calculations are listed and may be used for comparisons. For the $d^3Π_u^-$,v=4-6,N=1 levels of the $H_2$ molecule the lifetimes caused by predissociation via non-adiabatic interaction with continuum of the $c^3Π_u^-$ electronic state were estimated for the first time in the basis of experimental and semiempirical data.

physics.chem-ph↗

arXiv2015

Atlas and wavenumber tables for visible part of the multiline electronic-vibro-rotational emission spectrum of the $D_2$ molecule measured with moderate resolution in deuterium plasma with minor hydrogen impurity

The visible part ($\approx 419-696$ nm) of the multiline electronic-vibro-rotational emission spectrum of the $D_2$ molecule was recorded with moderate resolution mainly limited by Doppler broadening of spectral lines (line widths FWHM less than $0.013$ nm). After numerical deconvolution of the recorded intensity distributions and proper calibration of the spectrometer the new set of wavenumber values was obtained. It is shown that new data are significantly more precise than those available for visible part of the $D_2$ spectrum. Final results are reported as a supplement in the form of an atlas divided into 158 sections (each section covers about 1.5 nm) containing pictures of images in the focal plane of the spectrometer, intensity distributions in linear and logarithmic scales and the table containing wavenumber and relative intensity values for 11941 spectral lines together with available and new line assignments for the $D_2$ and $HD$ molecules.

physics.chem-ph↗

arXiv2014

Lifetimes of vibro-rotational levels for excited electronic states of the diatomic hydrogen isotopologues

Current situation in studies of lifetimes of excited rovibronic levels for the H2, D2, T2, HD, HT, and DT molecules is analyzed. All measured values of the lifetimes (792 data for 618 different vibro-rotational levels of 33 electronic states), reported in 61 publications before November 2014, are compiled and listed in the tabular format together with annotated bibliography. Experimental data are now available for the H2, HD and D2 molecules only. The data collected in the present work show fragmentariness of experimental data. For vast majority of the levels the lifetime value was reported in one paper only, and has no independent experimental verification. Complete bibliography of publications concerning semi-empirical determination and non-empirical calculations of the lifetimes is presented. Numerical results obtained by these two approaches are listed in an explicit form only in the cases when experimental data are available. For more than half of the levels the differences between measured and calculated values are 3 times higher than experimental errors. This direct contradiction shows necessity of more precise experimental and non-empirical studies. For finite number of rovibronic levels our analysis made it possible to propose certain set of recommended data.

physics.chem-ph↗

arXiv2013

Atlas and wavenumber tables for visible part ($419 ÷696$ nm) of the rovibronic multiline emission spectrum of the $D_2$ molecule measured with moderate resolution

The visible part ($\approx 419 ÷696$ nm) of the multiline electronic-vibro-rotational emission spectrum of the $D_2$ molecule was recorded with moderate resolution (line widths $\approx 0.013$ nm). The resolution was limited by Doppler broadening of spectral lines. After numerical deconvolution of the recorded intensity distributions and proper calibration of the spectrometer the new set of wavenumber values was obtained. The results are reported in the form of an atlas divided into 158 sections (each section covers about 1.5 nm) containing pictures of images in the focal plane of the spectrometer, intensity distributions in linear and logarithmic scales and the table containing wavenumber and relative intensity values for 11990 spectral lines together with existing line assignments.

physics.optics↗

arXiv2012

Atlas and wavenumber tables for visible part of the rovibronic multiline emission spectrum of the $D_2$ molecule. II. Wavenumber range $18161 ÷14379$ cm$^{-1}$ measured with moderate resolution

The visible part ($\approx 550 ÷696$ nm) of the multiline electronic-vibro-rotational emission spectrum of the $D_2$ molecule was recorded with moderate resolution (line widths $\approx 0.013$ nm). The resolution was limited by Doppler broadening of spectral lines. After numerical deconvolution of the recorded intensity distributions and proper calibration of the spectrometer the new set of wavenumber values was obtained. The results are reported in the form of an atlas divided into 43 sections covering about 1.5 nm, containing pictures of images in the focal plane of the spectrometer, intensity distributions in linear and logarithmic scales and the table containing wavenumber and relative intensity values for 5445 spectral lines together with existing line assignments.

physics.chem-ph↗

arXiv2012

Atlas and wavenumber tables for visible part of the rovibronic multiline emission spectrum of the $D_2$ molecule. I. Wavenumber range $23894 ÷18161$ cm$^{-1}$ measured with moderate resolution

The visible part ($\approx 419 ÷550$ nm) of the multiline electronic-vibro-rotational emission spectrum of the $D_2$ molecule was recorded with moderate resolution (line widths $\approx 0.013$ nm). The resolution was limited by Doppler broadening of spectral lines. After numerical deconvolution of the recorded intensity distributions and proper calibration of the spectrometer the new set of wavenumber values was obtained. The results are reported in the form of an atlas divided into 36 sections covering about 1.5 nm, containing pictures of images in the focal plane of the spectrometer, intensity distributions in linear and logarithmic scales and the table containing wavenumber and relative intensity values for 6545 spectral lines together with existing line assignments.

physics.chem-ph↗

arXiv2012

Observation of the fine structure for rovibronic spectral lines in visible part of emission spectra of $D_2$

For the first time in visible part of the $D_2$ emission spectrum the pseudo doublets representing partly resolved fine structure of rovibronic lines have been observed. They are characterized by splitting values about 0.2 cm$^{-1}$ and relative intensity of the doublet components close to 2.0. It is shown that they are determined by triplet splitting in lower rovibronic levels of various $^3Λ_g^\pm \to c^3Π_u^-$ electronic transitions. It is proposed to use an existence of such partly resolved fine structure patterns for identification of numerous unassigned spectral lines of the $D_2$ molecule coming from great variety of triplet "gerade" electronic states to vibro-rotational levels of the $c^3Π_u^-$ state.

physics.chem-ph↗

arXiv2011

New set of experimental wavenumber values for visible part of emission spectrum ($545 ÷627$ nm) of the $D_2$ molecule with partly resolved fine structure of triplet-triplet rovibronic transitions

New set of wavenumber values for electronic-vibro-rotational (rovibronic) transitions in limited part of the emission spectrum of the $D_2$ molecule ($545 ÷627$ nm) have been measured with a precision $0.007 ÷0.1$ cm$^{-1}$ depending on the translational temperature in plasma, the signal-to-noise ratio, and the degree of overlap with adjacent spectral lines. For the first time partly resolved fine structure of the $D_2$ spectral lines has been observed in the visible part of the spectrum.

physics.chem-ph↗

arXiv2008

Tables of the mean lifetimes for excited electronic-vibro-rotational states of isotopomers of diatomic hydrogen

Current situation in studies of mean lifetimes of excited electronic-vibro-rotational states of hydrogen molecule (including the H2, D2, HD and T2 isotopomers) is reviewed in brief. All measured values of the lifetimes (published before November 2008) are collected and presented in tabular form. Complete bibliography of papers devoted to semi-empirical determination and non-empirical calculation of the lifetimes is presented. The experimental data obtained in various papers are compared with the results of semi-empirical determination and non-empirical calculations.

physics.optics↗

arXiv2008

Rovibronic energy levels for triplet electronic states of molecular deuterium

An optimal set of 1050 rovibronic energy levels for 35 triplet electronic states of $D_2$ has been obtained by means of a statistical analysis of all available wavenumbers of triplet-triplet rovibronic transitions studied in emission, absorption, laser and anticrossing spectroscopic experiments of various authors. We used a new method of the analysis (Lavrov, Ryazanov, JETP Letters, 2005), which does not need any \it a priori \rm assumptions concerning the molecular structure being based on only two fundamental principles: maximum likelihood and Rydberg-Ritz. The method provides the opportunity to obtain the estimation of uncertainties of experimental wavenumbers independent from those presented in the original papers. 234 from 3822 published wavenumber values were found to be spurious, while the remaining set of the data may be divided into 19 subsets of uniformly precise data having close to normal distributions of random errors within the subsets. New wavenumber values of 125 questionable lines were measured in the present work (20-th subset). Optimal values of the rovibronic levels were obtained from the experimental data set consisting of 3713 wavenumber values (3588 old and 125 new). The unknown shift between levels of ortho- and para- deuterium was found by least squares analysis of the $a^3Σ_g^+$, $v = 0$, $N = 0 ÷18$ rovibronic levels with odd and even values of N. All the energy levels were obtained relative to the lowest vibro-rotational level ($v = 0$, N=0) of the $a^3Σ_g^+$ electronic state and presented in tabular form together with standard deviations (SD) of the semi-empirical determination. New energy level values differ significantly from those available in literature.

physics.optics↗

arXiv2008

Optimal values of rovibronic energy levels for triplet electronic states of molecular deuterium

Optimal set of 1050 rovibronic energy levels for 35 triplet electronic states of $D_2$ has been obtained by means of a statistical analysis of all available wavenumbers of triplet-triplet rovibronic transitions studied in emission, absorption, laser and anticrossing spectroscopic experiments of various authors. We used a new method of the analysis (Lavrov, Ryazanov, JETP Letters, 2005), which does not need any \it a priory \rm assumptions concerning the molecular structure being based on only two fundamental principles: Rydberg-Ritz and maximum likelihood. The method provides the opportunity to obtain the RMS estimates for uncertainties of the experimental wavenumbers independent from those presented in original papers. 234 from 3822 published wavenumber values were found to be spurious, while the remaining set of the data may be divided into 20 subsets (samples) of uniformly precise data having close to normal distributions of random errors within the samples. New experimental wavenumber values of 125 questionable lines were obtained in the present work. Optimal values of the rovibronic levels were obtained from the experimental data set consisting of 3713 wavenumber values (3588 old and 125 new). The unknown shift between levels of ortho- and para- deuterium was found by least squares analysis of the $a^3Σ_g^+$, $v = 0$, $N = 0 ÷18$ rovibronic levels with odd and even values of $N$. All the energy levels were obtained relative to the lowest vibro-rotational level ($v = 0$, $N = 0$) of the $a^3Σ_g^+$ electronic state, and presented in tabular form together with the standard deviations of the empirical determination. New energy level values differ significantly from those available in literature.

physics.optics↗

arXiv2007

On the opportunity of spectroscopic determination of absolute atomic densities in non-equilibrium plasmas from measured relative intensities within resonance multiplets distorted by self-absorption

The opportunities of the application of the recently proposed approach in optical emission spectroscopy of non-equilibrium plasmas have been studied. The approach consists of several methods of the determination of {\em absolute} particle densities of atoms from measured {\em relative} intensities within resonance multiplets distorted by self-absorption. All available spectroscopic data concerning resonance spectral lines of atoms having multiplet ground states from boron up to gallium were analyzed. It is found that in the case of C, O, F, S and Cl atoms an application of the methods needs VUV technique, while densities of B, Al, Si, Sc, Ti, V, Co, Ni, Ga atoms may be obtained by means of the intensity measurements in UV and visible parts of emission spectra suitable for ordinary spectrometers used for optical diagnostics and monitoring of non-equilibrium plasmas including industrial plasma technologies.

physics.plasm-ph↗

arXiv2005

Tables of rovibronic term values for singlet electronic states of BH molecule

The method for objective (based on Ritz principle only) and optimal determination of electronic-vibro-rotational (rovibronic) term values from meassured wavenumbers recently proposed in our previous paper is applied for singlet electronic states of $^{11}$BH molecule, namely $X^1Σ^+$, $A^1Π$, $C'^1Δ$, $B^1Σ^+$, $C^1Σ^+$, $D^1Π$, $E^1Σ^+$, $F^1Σ^+$, $G^1Π$, $H^1Δ$, $I^1Σ^+$, $J^1Σ^+$. All known to authors experimental data on the wavenumbers of rovibronic spectral lines are used. Those are the wavenumber values of 1563 spectral lines of 15 band systems, obtained in 10 different original papers. As a result 529 term values with their standard deviations were derived.

physics.chem-ph↗

arXiv2004

On determination of electronic-vibro-rotational term values of diatomic molecules from measured wavenumbers

A method is proposed for determining rovibronic term values of diatomics from experimental data on the wavenumbers of electronic-vibro-rotational spectral lines. In contrast to existing techniques, the new one is based on the Rydberg-Ritz principle only. It is shown that a link between a set of rovibronic term values and a set of wavenumbers of observed rovibronic spectral lines appears when three and more different electronic-vibrational states are pairwise-connected by radiative transitions. The method differs from known techniques in several aspects, namely, it: 1) doesn't need any assumptions concerning an internal structure of a molecule; 2) doesn't involve any intermediate parameters (as molecular constants in traditional techniques); 3) gives an opportunity to use in one-stage optimization procedure all available experimental data obtained for various band systems, by various authors, and in various works; 4) provides in an interactive mode the opportunity to select the experimental values, eliminating rough errors, to revise wrong identifications of spectral lines and to compare various sets of experimental data for mutual consistency; 5) allows to obtain not only an optimal set of rovibronic term values, but also the error bars depending on quantity and quality of existing experimental data. Necessary precondition for use of this method is a preliminary identification of electronic-vibro-rotational lines to certain electronic-vibro-rotational radiative transitions. For this purpose one has to use traditional methods of the analysis of molecular spectra.

physics.optics↗

arXiv2003

Determination of absolute densities of B, Al, Ga and Si atoms in non-equilibrium plasmas from relative intensities in resonance multiplets distorted by reabsorption

The approach proposed recently as a spectroscopic tecnique of a boron density determination in microwave plasma has been expanded for B, Al, Ga, Si atoms and generalized. The method is based on measurements of relative intensities of pairs of spectral lines belonging to resonance multiplets having common upper level. It is shown that when the reabsorption of the lines within plasma is sufficient, then the intensity ratios depend on the gas temperature T and the product NL of total density of the ground state atoms N and a length of a plasma column L. Thus in the case of the B, Al, Ga doublets the temperature T should be known. The resonance multiplet of Si (three independent intensity ratios) provides an opportunity to obtain both T and N and even to organize internal check of the applicability of the proposed method to certain plasma conditions. The ratios were calculated for resonance lines of B, Al, Ga and Si under T=300-2400 K and NL=10^7-10^15 cm^(-3) m. The results of numerical calculations and ranges of applicability of the method are discussed.

physics.plasm-ph↗

arXiv2001

Novel Mechanism for Single Bubble Sonoluminescence

Careful re-examination of typical experimental data made it possible to show that the UV continua observed in multi-bubble (MBSL) and single-bubble (SBSL) sonoluminescence spectra have the same physical nature - radiative dissociation of electronically excited hydrogen molecules [and probably hydrides of heavy rare gases like ArH*] due to spontaneous transitions between bound and repulsive electronic states. The proposed mechanism is able to explain all available spectroscopic observations without any exotic hypothesis but in terms usual for plasma spectroscopy.

physics.plasm-ph↗

arXiv1998

UV continuum emission and diagnostics of hydrogen-containing non-equilibrium plasmas

For the first time the emission of the radiative dissociation continuum of the hydrogen molecule ($a^{3}Σ_{g}^{+} \to b^{3}Σ_{u}^{+}$ electronic transition) is proposed to be used as a source of information for the spectroscopic diagnostics of non-equilibrium plasmas. The detailed analysis of excitation-deactivation kinetics, rate constants of various collisional and radiative transitions and fitting procedures made it possible to develop two new methods of diagnostics of: (1) the ground $X^{1}Σ_{g}^{+}$ state vibrational temperature $T_{\text{vib}}$ from the relative intensity distribution, and (2) the rate of electron impact dissociation $(d[\mbox{H$_{2}$}]/dt)_{\text{diss}}$ from the absolute intensity of the continuum. A known method of determination of $T_{\text{vib}}$ from relative intensities of Fulcher-$α$ bands was seriously corrected and simplified due to the revision of $d \to a$ transition probabilities and cross sections of $d \gets X$ electron impact excitation. General considerations are illustrated with examples of experiments in pure hydrogen capillary-arc and H$_{2}$+Ar microwave discharges.

physics.plasm-ph↗