Anatoly Pravilov

Saint Petersburg State University | SPBU · Faculty of Physics

The ArICl(ion-pair states) (IP) van der Waals (vdW) complexes populated in the ArICl(IP vIP,nIP←A1,vA,nA=0←X,0,nX=0) excitation pathway have been observed and studied for the first time. Analysis of the luminescence excitation spectra, luminescence spectra themselves and temporal behavior of the luminescence intensities of the transitions observed...

The N2I2(E) van der Waals complexes have been observed and studied for the first time. Analysis of the luminescence excitation spectra as well as luminescence spectra themselves in the spectral ranges, where the I2(D → X, β1g → A1u and D’2g → A’2u) transitions can occur, has been carried out. Branching ratios of the iodine molecule state formation...

The T-shaped NeI2(E0g⁺) van der Waals (vdW) complexes populated in the NeI2(E,vE = 0–2, nE=0–2 ← B,19,nB = 0 ← X,0,nX = 0) excitation pathway have been studied. Analysis of the luminescence excitation spectra, luminescence spectra themselves and temporal behaviors of the luminescence intensities of the transitions observed has been carried out. The...

The T-shaped KrI2(E ) van der Waals complexes have been observed and studied for the first time. Analysis of the luminescence excitation spectra as well as luminescence spectra themselves in the spectral ranges, where the I2(E → , D →X , β1g→A1u and D’2g→A’2u) transitions can occur, has been carried out. Branching ratios of the iodine molecule stat...

Detailed analysis of interactions between all 0g+, 1u, and 0u− weakly bound states of iodine molecule correlating with the I(2P1/2) + I(2P1/2) (bb) dissociation limit has been performed. For this purpose, the 0u− (bb) state has been described using analysis of rotationally resolved excitation spectra of luminescence from the g0g− state populated in...

The ArI2(E0g+) van der Waals complexes have been observed and studied for the first time. Analysis of the luminescence excitation spectra as well as luminescence spectra themselves in the spectral ranges, where the I2(E0g+→B0u+,D0u+→X0g+,β1g → A1u and D′2g → A′2u) transitions can occur, has been carried out. It has been shown that the I2(D → X, β →...

Non-adiabatic transitions from the I2(E0g+, D0u+, β1g and D′2g) states to first tier ion-pair (IP) states induced by collisions with Ar atoms have been investigated. The stepwise laser excitation schemes have been used for selective population of close-lying vibronic states: E, vE = 13, D, vD = 18, β, vβ = 19 and D′2g, vD′ = 23. Rate constants of p...

Luminescence spectra corresponding to transitions from β1g, G1g, D′2g, and &$g0_{{\rm g}}^{-}$; ion-pair states of an iodine molecule to weakly bound valence states 1u, 2u, and &$0_{{\rm u}}^{-}$; , correlating with the I(2P 3/2) + I(2P 1/2) (ab) and I(2P 1/2) + I(2P 1/2) (bb) dissociation limits, respectively, have been observed and analyzed. Ener...

The three-step three-color laser population of the I2(β1g, νβ, Jβ and $D0_{{\rm u}}^{+}$, νD, JD) rovibronic states via those of the $B0_{{\rm u}}^{+}$ and 1u, $0_{{\rm g}}^{+}$(bb) states, correlating with the second and third dissociation limits of the valence states, has been used for the study of mechanisms of optical transitions involved in th...

The stepwise three-step three-color laser population of the I2(β1g, νβ, Jβ) rovibronic states via the $B0_{{\rm u}}^{+}$, νB, JB rovibronic states and rovibronic levels of the 1u(bb) and $0_{{\rm g}}^{+}$(bb) states mixed by hyperfine interaction is used for determination of rovibronic level energies of the weakly bound I2(1u(bb)) state. Dunham coe...

Bound-free electric dipole allowed and bound–bound electric dipole allowed and electric dipole forbidden transitions at a fundamental harmonic of the Nd:YAG laser, , have been studied. Excitation spectra of the I2 (B, vB, JB → X, vX = 1, JX) luminescence from the B, vB = 18, 20, 21, JB rovibronic states have been measured with switched on and switc...

The stepwise three-step three-colour I2(D0+u, vD, JD 0+g, v0, J0B0+u, vB, JB X0+g, vX, JX) laser excitation scheme and rotational as well as rovibrational energy transfer processes in the 0+g state induced by collisions with He and Ar atoms are used for determination of rovibronic level energies of the weakly bound 0+g state correlating with the I(...

The stepwise two-step two-color and three-step three-color laser excitation schemes are used for selective population of rovibronic levels of the first-tier ion-pair E0(g)(+) and D0(u)(+) states of molecular iodine and studies of non-adiabatic transitions to the D and E states induced by collisions with M = I(2)(X) and H(2)O. Collection and analysi...

The results of measurements and analysis of excitation spectra of the λlum=2350Ǻ luminescence corresponding to I2(D0+u→X0+g) transition as well as luminescence at λlum=3400Ǻ, where I2(D’2g→A’2u and/or β1g→A1u) transitions occur, observed after three-step, λ1+λf+λ1, λ1=5321–5508.2Ǻ, λf=10644.0Ǻ, laser excitation of pure iodine vapour and I2+Xe mixtu...

The dipole moment functions of the iodine &\mathop {{\rm D^{\prime} }2}\nolimits_g \hbox{--}{ {\rm A}^{\prime} }2_u; and &{\rm D}0_u^ + \hbox{--}\mathop {{\rm {\rm a}^{\prime}}0}\nolimits_g^ +; transitions in the ranges of 3.0–4.8 and 3.1–4.1 Å have been determined for the first time by means of simulation of the luminescence spectra from the D', v...

The stepwise three-photon two-color laser excitation scheme is used for selective population of the first-tier ion-pair D0(+)(u) state of molecular iodine. Collection and analysis of the luminescence after the excitation of the v(D) = 6, 8, 13 and 18 vibronic levels of the D state in the pure iodine vapor and the gas-phase mixtures with He, Ar and...

The first results of measurements and analysis of excitation spectra of the λlum = 3250 Å luminescence corresponding to I2(D0 u + → X0 g +) transition as well as luminescence at λlum = 3400 Å, where I2(D′2 g → A′2 u and/or β1 g → A1 u ) transitions occur, observed after three-step, λ1 + λ f + λ1, λ1 = 5321–5508.2 Å, λ f = 10644.0 Å, laser excitatio...

Results of the first studies of temporal behavior of luminescence in the λ = 235–275 nm and λ = 315–350 nm spectral ranges following optical-optical double resonance (OODR) excitation of I2 + Xe mixtures to the I2(f, vf = 9, Jf ≈ 55) state as well as time-gated luminescence spectra measured with Δt = 10–70 ns time delay from the beginning of the la...

Pressure dependences of luminescence intensities of the I2(E0g+→B0u+,D0g+→X0g+andβ0g+→A1u) transitions, temporal histories of the luminescence and luminescence excitation spectra at different time delays from the beginning of the probe laser pulse under OODR photolysis of the I2 + SF6 mixture have been measured. A comparison of experimental depende...

The luminescence excitation spectra and the luminescence spectra of the I2 + Rg (Rg = He, Ar, Xe; p Rg = 2–20 Torr) mixtures measured at room temperature by the method of double optical resonance in the spectral range corresponding to the population of the I2(f0 g +, v f = 8.9) levels and in its vicinity are analyzed in this work. The experimental...

Nonadiabatic transitions among the first-tier ion-pair states of the iodine molecule in collisions with CF4 and SF6 partners are investigated by detecting the luminescence following the optical-optical double resonance excitation of the E0g+-state to the vibrational levels vE = 8, 13, and 19. Total and partial rate constants, as well as vibrational...

Optical–optical double resonance spectroscopy is used to obtain total rate constants, electronic branching ratios, and vibrational product state distributions for non-adiabatic transitions among the first-tier ion-pair states of the I2 molecule excited to the E0g+,vE=8,13,19;JE ≈ 55 rovibronic levels in collisions with M = CD3I and CH3COCH3. It is...

Optical–optical double resonance spectroscopy is used to obtain total rate constants, electronic branching ratios, and vibrational product state distributions for non-adiabatic transitions among the first-tier ion-pair states of the I2 molecule excited to the E0g+, vE = 8, 13, 19; JE ≈ 55 rovibronic levels in collisions with M = I2, N2 and CO2. It...

Measurements were made of the absorption coefficients of RI=CF3I, C3F7I, CF3CFICF3, and CF3OCF2CF2I in the 120–320 nm spectral range. Investigations were made of the photodissociation processes of CF3OCF2CF2I at λ=254 nm and of the spectral dependences of the main photodissociation processes of RI in the first two vacuum ultraviolet (VUV) bands (15...

A method is proposed for measuring the spectral distribution of the absolute quantum yield of O(1S) in the photolysis of oxygen-containing compounds (RO). This involves investigating the luminescence excitation spectra of XeO* excimers formed in the O(1S)+Xe+XeXeO*+Xe reaction. The measurements were made in a following RO–Xe mixture of accurately k...

Experimental and theoretical investigations were made of the elementary processes occurring in the course of recombination of H(2p), D(2p), and He atoms at T = 293 K. The decay of the vibrational levels of the B 2Π state of the HeH and HeD molecules was greatly influenced by the collision-induced predissociation at a rate close to gaskinetic, the c...

The main primary processes in the photolysis of C3F7I (λ =254 nm) were found to be photodissociation into C3F7 and two iodine atoms in the states 2P1/2 (absolute quantum yield ΦI* = 0.95+0.05–0.08) and 2P3/2 (ΦI≈0.05). The photodissociation of CF3I, C3F7I, and CF3CFICF3 in the vacuum ultraviolet (λ=155–175 nm) gave the following results: ΦI*=0.0±0....

An analysis is made of the general laws governing the spectroscopy of diatomic and polyatomic iodides in the UV–VUV parts of the spectrum and their spectroscopic properties are compared with published data on the primary photolysis processes. Particular attention is paid to alkyl iodides and perfluoroalkyl iodides. An attempt is made to interpret t...

Spectral and kinetic analysis of luminescence in the lambda = 220 500 nm spectral range observed after three-step, 532.124 + 1024.48 + 532.24 nm, laser excitation of the I2 + Rg mixtures, Rg = He Xe, in wide 2. 7 100 Torr Rg pressures shows that one cannot describe the spectral features as well as their dependences on Rg pressures in framework of c...

A considerable difference of iodine emission spectra after optical–optical double resonance excitation of the E0+g, vE = 19, JE ≈ 55 and JE ≈ 85 rovibronic levels is observed. The latter include strong transitions from the γ1u ion-pair state to valence ones. This feature is interpreted as a result of hyperfine coupling of near-resonant E0+g, vE = 1...

Optical–optical double resonance spectroscopy and quantum scattering calculations are used to obtain total rate constants, electronic branching ratios, and vibrational product state distributions for non-adiabatic transitions among the first-tier ion-pair states of the I2 molecule excited to the E0g+,vE=8,19,JE≈55 rovibronic levels in collisions wi...

The luminescence spectra of I2(β1g,νβ⩽59 and D0u+, νD⩽61) ion-pair states are observed in I2+Rg mixtures after irradiation by Nd:YAG (1064.48 and 532.24nm) laser beams. Luminescence excitation is attributed to two-step 1064.48+532.24nm pumping of RgI2 complexes in 0g+ and 1u valence states correlating to third valence dissociation limit 2P1/2+2P1/2...

Nonadiabatic transitions induced by collisions with He, Ar, Kr, and Xe atoms in the I(2) molecule excited to the f0(g)(+) second-tier ion-pair state are investigated by means of the optical-optical double resonance spectroscopy. Fluorescence spectra reveal that the transition to the F0(u)(+) state is a dominant nonradiative decay channel for f stat...

Luminescence and luminescence excitation spectra in the vicinity of the optical optical double resonance transitions to the I2(f0g+, vf = 8 and 9, Jf ≈ 55) levels have been measured at the bulb conditions for the I2 + Rg mixtures (Rg = He, Ar, Xe) at the rare gas pressures 2 20 Torr and room temperature. Luminescence attributed to the RgI2 compl...

The emission spectra caused by the transitions from the ion-pair states and f0 g + and G1g of the I2 molecule are obtained by excitation of individual rovibronic levels of the molecule by the method of optical-optical double resonance. The emission spectra from the state F0 u + populated due to collisions I2(f) + I2(X) are also measured. By modelin...

The ion-pair states of molecular iodine provide a unique system for studying the efficiency, selectivity, and mechanisms of collision-induced non-adiabatic transitions. Non-adiabatic transitions between the first-tier ion-pair states in collisions with molecular partners and rare gases are analyzed and discussed. The qualitative features of the rat...

Non-adiabatic transitions from the f0g+ state of the iodine ion-pair (IP) second tier induced by collision with iodine ground state molecules have been studied for the first time. The only I2(f0g+,vf,Jf→I2(X)F0u+,vF,JF) transition has been observed. No transitions between the states of the first and second tiers have been found. The dependences of...

The electric dipole moment functions of iodine E0g+–A1 u and E0g+–B''1 u transitions in the range of 3.2–4.2 Å have been determined for the first time by simulating the luminescence spectra from the E0g+,v E = 9, JE ≈ 55 rovibrational level and the measured ratios of the total intensities of the E0g+–A1 u, E0g+–B''1 u and E0g+–B0 u+ transitions.

The dependences of the , M=He, Ar, N2,CF4, transition rate constants on the vibrational vE, vD, rotational JE, JD quantum numbers, energy gaps, as well as their correlations with Franck–Condon factors of the initial and final levels have been studied. Intramolecular transitions induced by the C3/R3 term of multipole series of potential energy opera...

The results of nonempirical calculations of the electronic structure, spectroscopic constants, and potential-energy curves for the covalent and triplet ionic-pairing states of the F2 molecule are presented. It is shown that the covalent 13Πu state is weakly bound, with the depth of the potential well of this state being of about 0.05–0.2 eV. The ef...

The dependences of the I2( E0g+,v E,J E limit→M D0 u+,v D,J D) , M=He, Ar, N 2,CF 4, transition rate constants on the vibrational vE, vD, rotational JE, JD quantum numbers, energy gaps, as well as their correlations with Franck-Condon factors of the initial and final levels have been studied. Intramolecular transitions induced by the C3/ R3 term of...

Gas phase emission spectra of the hitherto unknown free radical PbLi have been measured in the NIR range with a Fourier-transform spectrometer. The emissions were observed from a fast flow system in which lead vapor in argon carrier gas was passed through a microwave discharge and mixed with lithium vapor in an observation tube. Five electronic tra...

The dependences of the collisional induced transition rate constants on the vibrational vE,vD, rotational JE quantum numbers, energy gaps, and Franck–Condon factors of the combined levels have been studied in the range of vD=1–5. It has been shown that all the observed collisional induced intramolecular transitions (CIIT) are nonresonant and corres...

The dependences of the transition rate constants on the vibrational vE,vD, rotational JE,JD quantum numbers, energy gaps, and Franck–Condon factors of the combined levels have been studied in the range vE=8–23. The extremely long-range near-resonance process as well as nonresonant transitions, corresponding to the energy loss up to (approximately t...

The dependences of the I2( E0g+,v E,J Elimit→I2( X) D0u+,v D,J D) transition rate constants on the vibrational vE, vD, rotational JE, JD quantum numbers, energy gaps, and Franck-Condon factors of the combined levels have been studied in the range vE=8-23. The extremely long-range near-resonance I2( E,v Elimit→I2( X) D,v D) process as well as nonres...

The dependencies of rate constant of the intramolecular ) approach-induced transition, M=He, Ar, I2, N2, CF4, on the vibrational vE, vD, rotational JE, JD numbers, energy gaps, and Franck–Condon factors of the combined levels have been studied at nearly single-collision conditions by the OODR method. It has been shown that the observed approach-ind...

The dependencies of rate constant of the intramolecular I2( E0g+ limit→M D0u+) approach-induced transition, M=He, Ar, I 2, N 2, CF 4, on the vibrational vE, vD, rotational JE, JD numbers, energy gaps, and Franck-Condon factors of the combined levels have been studied at nearly single-collision conditions by the OODR method. It has been shown that t...

Gas-phase emission spectra of the hitherto unknown free radical BiNa have been measured in the NIR range with a Fourier transform spectrometer. The emissions were observed from a fast-flow system in which bismuth vapor in argon carrier gas was passed through a microwave discharge and mixed with sodium vapor in an observation tube. Two systems of bl...

Bound–bound and bound-free luminescence spectra of molecular chlorine have been measured in the 210–330 nm spectral range after OODR excitation. The relative dipole moment functions of the transitions as well as potential energy curves of the repulsive states correlated with the Cl(2P3/2) + Cl(2P3/2), Cl(2P1/2) + Cl(2P3/2) and Cl(2P1/2) + Cl(2P1/2)...

The optical-optical double-resonance technique has been used for measurements of emission spectra from separate vibrational levels of the 1(3P2) state of ICl (v´ = 12 and 14) populated via the A 1 3 state. The electric dipole moment function of the A transition has been determined over the range of the internuclear distance of 0.29-0.39 nm by means...

The dependences of the I2( E, v E limit↔I2( X) D, v D) collision-induced transition rate constant on the vibrational vE, vD, rotational JD numbers, energy gaps, and Franck-Condon factors (FCF) of the combined levels have been studied. Selected rovibrational levels of the E state have been produced by optical-optical double resonance (OODR) excitati...

The dipole moment functions, μe( R), have been determined for the iodine E0 g+-B0 u+ and D0 u+-X0 g+ transitions over the regions R=0.31-0.48 and 0.305-0.45 nm, respectively, from the spectrally resolved emission of the E and D states. Single rovibrational levels of the E state have been pumped by optical-optical double resonance technique via the...

Spectra in the N+O, N+N and O+NO chemiluminescence reactions, -535, 500-1050 and 400-1150 nm respectively, have been measured in a pure environment with an accuracy up to 2%. These spectra can be utilized for calibration of the sensitivity of spectrometer/detector systems used for measurements of chemiluminescence spectra of gas-phase reactions. Th...

For determining the efficiency of a vacuum-UV monochromator with a multiplier type PMT-142 in the range 110 - 450 nm two different methods for absolute and six methods for relative calibrations were used. The results of all relative calibrations except for one agree to within an accuracy close to the experimental error in the range of their mutual...

Spectra accompanying oxygen atom recombination have been measured in the 280 - 600 nm spectral range, at all- and approximately all-He and all- baths with 2 nm spectral resolution and an accuracy of several per cent. Emission bands from the and vibronic levels have been observed and assigned by a simulation procedure. Intensities of individual band...

Specific rovibrational levels of the E0g+ ion-pair state of Cl2 have been laser excited by optical–optical double resonance (OODR) via the B0u+ state. A two-color, single-laser visible+ultraviolet (VIS+UV) scheme was used, where the UV radiation was derived by second-harmonic generation from the VIS laser output. Spectrally resolved emission at 240...

The b1Sigma+(b0(+)) left and right arrow X3Sigma-(X10(+),X21) transitions of SbH and SbD have been studied by laser-induced fluorescence measurements. Ground state SbH(SbD) radicals were generated in a fast-flow system by reaction of microwave-discharged hydrogen (deuterium) with antimony vapor. Vibrational levels v = 0 and 1 of the b1Sigma+ state...

The b1Σ+(b0+) ↔ X3Σ−(X10+,X21) transitions of SbH and SbD have been studied by laser-induced fluorescence measurements. Ground state SbH(SbD) radicals were generated in a fast-flow system by reaction of microwave-discharged hydrogen (deuterium) with antimony vapor. Vibrational levelsv= 0 and 1 of theb1Σ+state were excited with a pulsed dye laser. I...

Two-step laser E ← B ← X excitation of an iodine molecule is used to determine of the dependence of the dipole moment of the I2(E0g+-B0u+) transition on the internuclear distance. Factors determining the error of measuring this function are considered.

Relative dipole moments of the Cl2 (A-X) and (B-X) transitions and vibronic level populations have been determined by measurements of the spectra of chlorine atom recombination accompanied by optical rovibronic transitions. Laser photolysis of Cl2+He mixtures with helium pressures up to 10 atm was used for the production of chlorine atoms and the p...

The effect of isotopic substitution on the chemiluminescence that occurs during the recombination of the N(4S) and O(3P) atoms has been studied for the following isotope combinations: 14N + 16O, 15N + 16O, 14N + 18O, 15N + 18O. Emissions in the NO δ, γ, β and Ogawa bands were identified in the spectra. Isotopic substitution caused remarkable change...

The processes of the recombination of perfluoroalkyl radicals with iodine atoms in the ground I(5p 52P 3/2) and first excited I(5p 52P 1/2) electron states accompanied by radiation, R( overlineX)+I(5p 52P 1/2)→ (M) RI( 3Q 0+, v')→RI( overlineX)+ hv (i), R( overlineX)+I(5p 52P 3/2)→RI( 1Q, 3Q 1; v')→RI( overlineX+ hv (ii), have been studied by the m...

The method of quantitative laser induced chemiluminescent kinetic spectroscopy (QLICKS) is developed for the study of chemiluminescence reactions. This method enables us to determine spectral distributions of chemiluminescence rate constants kcl(λ) (photon cm3/particle2 s nm) and total chemiluminescence rate constants kcl (photon cm2/particle2 s)....

PbF radicals were produced in a fast-flow system by reaction of lead vapour with molecular fluorine. The ground state molecules were excited to selected vibrational levels of the A 3∑ + state by absorption of pulsed dye laser radiation in the wavelength range 400-450 nm. Radiative and collisional deactivation of the A state was found to efficiently...

The method of quantitative laser induced chemiluminescent kinetic spectroscopy (QLICKS) is developed for the study of chemiluminescence reactions. This method enables us to determine spectral distributions of chemiluminescence rate constants kcl(λ) (photon cm 3/particle 2 s nm) and total chemiluminescence rate constants kcl (photon cm 2/particle 2...

Emission of XeF*(B,C) excimers was observed when XeF2 was added to active nitrogen. This indicates XeF* formation in the process of dissociative electronic energy transfer from N*2 to XeF2: N*2+XeF2→XeF*+N2+F. The termolecular rate constant for XeF excitation in active nitrogen has been measured to be 10−34 cm6 s−1. The formation of XeF* in the rea...

Recombination of the I(2P1/2) and I(2P3/2) atoms accompanied by radiation [MATH] (1) has been studied. Spectra and rate constants have been measured : k1 = 10+10-5, 7+7-4, 3+3-1,5 (M = He, Ar, CF3CFICF3, respectively) ; units, 10-15photon cc/particle2s. It has been found out that the reaction (1) can be described by the complex formation mechanism....

The kinetics of xenon excitation in active nitrogen were studied using the emission of XeCl* excimers formed in the reaction as a marker for Xe* metastable states. This method enables the total yield of xenon excitation in reaction (1) to be obtained, which is basically associated with Xe[;6s]; state formation. Termolecular rate constants for xenon...

The most recent HeH potential energy curves and dipole transition moments by Theodorakopoulos and co-workers are employed to study radiative and nonradiative transitions from the bound B 2Π state to the repulsive X 2Σ+ state. The emission spectra Aν′ (v) and the radiative lifetimes τrB,ν′ are calculated for B, ν′ = 0–8→X the Franck-Condon semiclass...

The VMS-M universal small-sized vacuum monochromator with high aperture ratio is described. The monochromator operates in the near infrared - vacuum ultraviolet spectral regions. The monochromator is independent functional unit which can be used as a set equipment. The monochromator is convenient in application as an illuminator, spectrophotometer...

The excitation of Xe {6p} atoms in the nitrogen afterglow was studied using Xe {6p} → Xe {6s} emission. Xenon levels lying close to the N2 dissociation limit D0(N2) (6p[ 5 2]3, 6p[ 3 2]1 and 6p[ 3 2]2 are directly excited in the process of three-body recombination {A figure is presented}. The population of the xenon levels 6p[ 1 2]1 and 6p[ 5 2]2 w...

Measurements were made of the absolute quantum yields of I(2P1/2) atoms, ΦI* (λ), in the photolysis of C2H5I and C3H7I in the λ = 240–290 nm spectral range. It was established that nonadiabatic processes influence the values ΦI* (λ).

A study of the mechanism for N 2(B 3Π g) deactivation by N 2 has been carried out using chemiluminescence in the reaction N( 4S) + N( 4S)(+M) → N 2(B 3Π g, ν' → N 2(A 3Σ u+, ν″) + hv. Different N 2 isotopes were used as excited and third-body molecules. N 2(B 3Π g, ν) deactivation was found to involve electronic energy transfer: 15N 2(B 3Π g, ν 1)...

Polarized luminescence generated by two-particle atom photorecombination involving two molecular terms is studied theoretically. The conditions for generation of polarized luminescence are shown to be either electronic polarization of ensembles of interacting atoms or anisotropy of their relative motion. Formulas for the linear and circular polariz...