Oscillator Strengths Of Absorption Bands Research Articles

Concentration Dependent Luminescence and Energy Transfer Properties of Samarium Doped LLSZFB Glasses

Background: Recently, great importance has been devoted to borate glass systems doped with rare-earth ions because of their unique peculiar properties in the field of photonics for optical applications. Objective: The purpose of the present study is to investigate the effect of concentration of Sm3+ ions on the luminescence properties of lead fluoroborate glasses through the energy transfer mechanism. Materials and Methods: Samarium doped lead fluoroborate glasses with chemical composition 20PbF2 .10Li2O .5SrO .5ZnO. (60-x) B2O3. xSm2O3 (where x = 0.1, 0.5, 1.0, 1.5 and 2.0 mol %) were prepared by means of melt quenching method. The concentration dependent luminescence properties were investigated in detail from the optical absorption, photoluminescence and decay analysis. Judd-Ofelt (J-O) theory was applied to analyze the optical absorption spectra. The experimental oscillator strengths of absorption bands have been used to determine the J-O parameters. Using the J-O parameters Ωλ (λ = 2, 4 and 6) and luminescence data several radiative parameters were obtained. Results: From the luminescence spectra, it was noticed that luminescence quenching starts at higher concentrations of Sm3+ ions (x ≥ 0.5 mol %). The decay curves of 4G5/2 → 6H7/2 transition exhibit a single exponential at lower dopant concentrations (x= 0.1 and 0.5 mol %) and non-exponential at higher concentrations (x ≥ 1 mol %). The concentration quenching was attributed to the energy transfer through the cross-relaxation between Sm3+ ions. The non-exponential curves were well fitted to Inokuti-Hirayama model for S = 6, indicating that the energy transfer between Sm3+ - Sm3+ ions is of dipole-dipole type. The calculated color coordinates of the as-prepared glasses fall within the reddish-orange region of the CIE diagram. Conclusion: All the experimental results indicate that the 0.5 mol% Sm3+ ions doped LLSZFB glass can be a possible choice for solid state lighting and display applications.

Sm3+-Doped Molybdenum Gadolinium Borate Glasses for Orange Emission Laser Active Medium

Room temperature visible and near infrared optical absorption and emission spectra of Sm3+-doped molybdenum gadolinium borate (MGB) glasses with molar composition 25MoO3-20Gd2O3–(55 − x)B2O3−xSm2O3 (x = 0.05, 0.1, 0.5, 1.0, 2.0 mol.%) have been analyzed. The experimental oscillator strengths of absorption bands have been used to determine the Judd–Ofelt (J–O) parameters. Fluorescence spectra were recorded by exciting the samples at 402 nm. Using the J–O parameters and luminescence data, the radiative transition probabilities (AR), branching ratios (BR), and stimulated emission cross-sections oe) are obtained. The decay curves of the 4G5/2 - 6H7/2 transition exhibit a non-exponential curve fit for all concen-trations. The concentration quenching has been attributed to the energy transfer through the cross-relaxation between Sm3+ ions. 4G5/2 level and its relative quantum efficiencies are measured. Intense reddish-orange emission corresponding to the 4G5/2−6H7/2 transition has been observed in these glasses at the 487-nm excitation, From the values of the radiative parameters, it is concluded that the 1.0-mol% Sm3+-doped MGB glass may be used as a laser active medium with the emission wavelength at 599 nm. The analysis of the non-exponential behavior of decay curves through the Inokuti–Hirayama model indicates that the energy transfer between Sm3+ ions is of dipole–dipole type. The quantum efficiency for the 4G5/2 level of MGBSm10 glass is found to be 67%. The co-related color temperature obtained from CIE (Commission International de L’Eclairage) for these glass samples is ∼1620 K for the indicated orange emission at the 402-nm excitation.

Radiative transition probabilities for the main diatomic electronic systems of N2, [formula omitted], NO, O2, CO, CO+, CN, C2 and H2 produced in plasma of atmospheric entry

Accurate radiative transition probabilities of diatomic electronic systems are required to calculate the discrete radiation of plasmas. However, most of the published transition probabilities are obtained using older spectroscopic constants and electronic transition moment functions (ETMFs), some of which deviates greatly from experimental data. Fortunately, a lot of new spectroscopic constants that include more anharmonic correction terms than the earlier ones have been published over the past few years. In this work, the Einstein coefficients, Franck–Condon factors and absorption band oscillator strengths are calculated for important diatomic radiative transition processes of N2-O2, CO2-N2 and H2 plasmas produced in entering into the atmosphere of Earth, Mars and Jupiter. The most up-to-date spectroscopic constants are selected to reconstruct the potential energy curves by the Rydberg–Klein–Rees (RKR) method. Then the vibrational wave functions are calculated through the resolution of the radial Schrödinger equation for such potential energy curves. These results, together with the latest “ab-initio” ETMFs derived from the literature are used to compute the square of electronic-vibrational transition moments, Einstein coefficients and absorption band oscillator strengths. Moreover, the Franck–Condon factors are determined with the obtained vibrational wave functions. In the supplementary material we present tables of the radiative transition probabilities for 40 band systems of N2, N2+, NO, O2, CO, CO+, CN, C2 and H2 molecules. In addition, the calculated radiative lifetimes are systematically validated by available experimental results.

Photoluminescence properties of singly doped Tm3+ and co-doped Tm3+/Tb3+ ions in tellurite glasses

Photoluminescence properties of singly doped Tm3+ and co-doped Tm3+/Tb3+ ions in TZKC glasses with chemical composition of (61.5−x) TeO2+25 ZnO+8 K2O+5CaO+0.5Tm2O3+xTb4O7 (TZKCTm05Tbx; x (in mol%)=0, 0.5, 1.0, 1.5) have been studied. The experimental oscillator strengths of absorption bands in TZKCTm05 glass were used to determine the host dependent Judd–Ofelt Ω2, Ω4, Ω6 intensity parameters. The effective emission cross-section of 1.8μm emission band as a function of wavelength has been deduced by the McCumber’s theory. Based on the absorption (σa) and emission cross-sections (σe), the gain co-efficients (G) of 1.8μm emission band for various population inversions between the emitting (3F4) and terminating (3H6) levels were evaluated. From the photoluminescence spectra of singly doped Tm3+ and co-doped Tm3+/Tb3+ ions in TZKC glasses, the chromaticity color coordinates (x, y) were estimated.

Spectral and luminescent characteristics of trivalent lanthanide ions in a POCl3-SnCl4 inorganic solvent

We have measured the absorption and luminescence spectra of trivalent lanthanide ions (Pr3+, Sm3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, and Yb3+) in the visible and near-IR wavelength ranges in a POCl3-SnCl4 inorganic solvent. In terms of the Judd-Ofelt model, the oscillator strengths of absorption bands, the probabilities of radiative transitions, the luminescence branching coefficients, the lifetimes of excited states, and the luminescence quantum yields have been calculated. Possibilities of creating new laser media have been evaluated. A conclusion is drawn regarding the symmetry of the environment of trivalent lanthanide ions in the POCl3-SnCl4 solvent.

Optical and luminescent properties of Sm3+ doped tellurite glasses

Glasses with chemical composition of (62−x) TeO2+25 ZnO+8 K2O+5 CaO+x Sm2O3 (TZKCSmx; x=0.1, 0.5, 1.0, 1.5mol%) were prepared by melt quenching technique. The absorption spectrum was recorded in the UV–visible and NIR regions. The oscillator strengths of absorption bands were obtained by measuring the area under the bands. Judd–Ofelt analysis has been carried out to estimate the host dependent J–O intensity Ωλ (λ=2, 4, 6) parameters by least squares fitting approach. Photoluminescence spectra recorded in the visible region revealed intense green, orange and red emission bands in all the glasses, corresponding to the 4G5/2→6H5/2, 4G5/2→6H7/2 and 4G5/2→6H9/2 transitions respectively. From the emission spectra and J–O intensity parameters, various radiative parameters were calculated from the excited 4G5/2 to the lower lying 6HJ (J=5/2, 7/2, 9/2, 11/2) multiplet. Quenching of luminescence with the increase of Sm3+ ions concentration has been observed. Decay times of excited 4G5/2 state decrease with the increase of the Sm3+ ions concentration. The energy transfer mechanism that leads to the quenching of 4G5/2 state lifetime has been discussed. Inokuti–Hirayama (I–H) model was used to evaluate various energy transfer parameters, which are the qualitative indicators for the interaction among Sm3+ ions.

Erbium‐Doped Fluoroborate Glasses for Near Infrared Broadband Amplifiers

Erbium (Er3+)‐doped alkali lead tellurofluoroborate (RLTB) glasses were prepared and characterized systematically through optical absorption and emission measurements. The emission spectra in the range 450–900 and 1400–1800 nm were recorded by exciting the samples with 532 nm (Nd : YVO4 crystal) and 514.5 nm (Ar+ laser), respectively. Applying Judd–Ofelt analysis, the intensity parameters have been determined using experimental oscillator strengths of absorption bands. From the Judd–Ofelt intensity parameters, some important fluorescence properties such as spontaneous transition probabilities, radiative lifetimes and luminescence branching ratios for the 4S3/2→4I15/2 (0.55 μm), 4S3/2→4I13/2 (0.85 μm), and 4I13/2→4I15/2 (1.54 μm) emission transitions of Er3+ ion in RLTB glasses have been calculated. The continuous pumping of the samples results in fast nonradiative decay through 2H11/2→4F9/2 (~3500 cm−1) transition, which in turn causes the population of Er3+ ions from 2H11/2 state to the higher 4F3/2 state. The emission cross sections determined for the 4I13/2→4I15/2 (1.54 μm) transition using the McCumber theory are in good agreement with the values obtained from the Judd–Ofelt analysis. From evaluated radiative parameters, it is suggested that these RLTB glasses are more suitable candidates for 0.85 and 1.54 μm broadband optical amplifiers.

Photoluminescence and energy transfer properties of Sm 3+ doped CFB glasses

The present paper describes the optical absorption, photoluminescence and lifetime measurements of trivalent samarium doped calcium fluoroborate (CFB) glasses. From the observed energy levels, the free-ion energy level parameters for the 4f 5 electronic configuration of Sm 3+ ion have been evaluated using H FI model. The experimental oscillator strengths of absorption bands have been analyzed to determine the Judd–Ofelt (J–O) parameters. From the evaluated J–O parameters and luminescence data, the radiative parameters such as A R, τ R and σ e values were obtained from the excited 4G 5/2 level to different lower energy levels. The decay curves of 4G 5/2 → 6H 7/2 transition were analyzed by the Inokuti–Hirayama model assuming dipole–dipole interaction between the dopant ions. The decrease of fluorescence intensities as well as measured lifetimes at higher concentrations has been explained based on energy transfer process through cross-relaxation between Sm 3+ ions.

Calculation of radiative parameters for the $$ {A^1}\sum\nolimits_u^{+} {{X^1}} \sum\nolimits_g^{+} {} $$ -transition of cesium dimer

Radiative parameters for vibrational bands (0 ≤ v′ ≤ 30, 0 ≤ v′′ ≤ 59) of the $$ {A^1}\sum\nolimits_u^{+} {{X^1}} \sum\nolimits_g^{+} {} $$ -electronic transition of a cesium dimer are calculated. These include vibronic band wavenumbers, Franck–Condon factors, Einstein coefficients for spontaneous emission, absorption band oscillator strengths, and radiative lifetimes for vibrational levels of the excited electronic state. Vibrational energies and wave functions for the ground and excited electronic states were found by a numerical solution of the radial wave equation based on potential curves plotted during the course of the study.

Radiative transition parameters of the [formula omitted] band system

The relative band strengths of several absorption bands of the Ag 2 C 1 Π u – X 1 Σ g + system are measured for the first time. Ratios of observed strengths for bands with common lower vibronic levels are compared with theoretically predicted absorption band oscillator strengths, which we computed by numerically solving the radial Schrödinger equation for the vibrational wave functions, ψ υ ′ and ψ υ ″ of the Ag 2 107 , 109 C 1 Π u – X 1 Σ g + band system, using Rydberg–Klein–Rees potential energy curves and a suitable choice for the electronic transition moment function. This resulted in a useful set of radiative transition parameters for a large matrix of Ag 2 C– X bands. The functional form of the electronic transition moment required by the observed band strength ratios forces good agreement between the observations and diatomic molecular theory. Since the function is highly nonlinear, the commonly applied r-centroid approximation is invalid, and numerical integration of ∫ ψ υ ′ * R e ( r ) ψ υ ″ dr had to be performed instead. As a final check on the reliability of our results, we find good agreement between the experimentally measured displacements of band heads for the Ag 2 107 , 107 and Ag 2 109 , 109 isotopologues and the corresponding isotopic shifts of our calculated band origins.

Photoluminescence properties of Sm 3+ in LBTAF glasses

Room temperature visible and near infrared optical absorption and emission spectra of Sm 3+-doped lead borate titanate aluminum fluoride (LBTAF) glasses with molar composition (50− x) PbO−30H 3BO 3−10TiO 2−10AlF 3− xSm 2O 3 ( x=0.1, 0.5, 1.0 and 2.0) have been analyzed. Energy parameters for the 4f 5 electronic configuration of Sm 3+: LBTAF glasses have been evaluated using free-ion Hamiltonian model. The experimental oscillator strengths of absorption bands have been used to determine the J– O parameters. Fluorescence spectra were recorded by exciting the samples with 402 nm. Using the J– O parameters and luminescence data, the radiative transition probabilities ( A R), branching ratios ( β R) and stimulated emission cross-sections ( σ e) were obtained. The decay curves of 4G 5/2→ 6H 7/2 transition exhibit single exponential for lower concentration (0.1 mol%) and non-exponential for higher concentrations. This concentration quenching has been attributed to the energy transfer through cross-relaxation between Sm 3+ ions. From the values of the radiative parameters, it is concluded that 1.0 mol% Sm 3+-doped LBTAF glass may be used for laser active medium with emission wavelength at 600 nm.

Radiative transition parameters for the [formula omitted] band system of 107,109Ag 2

Radiative transition parameters are tabulated for the A 1 Σ u + - X 1 Σ g + band system of the silver dimer 107,109Ag 2 for bands involving vibrational levels up to v ′ = 54 and v ″ = 98 , which amply covers the band transitions empirically studied in the seminal work of Kleman and Lindkvist [B. Kleman, S. Lindkvist, Arkiv för Fysik 9 (1955) 385–390]. The tabulated parameters include band-origin wavelengths and wavenumbers, Franck–Condon factors, r-centroids, electronic transition moments, Einstein coefficients (spontaneous emission rates) and absorption band oscillator strengths. Rydberg–Klein–Rees potential energy curves for both electronic states, based on the latest available spectroscopic constants, were calculated, and then used to solve the radial Schrödinger equation for the vibrational wave functions, ψ v ′ and ψ v ″ . The constant electronic transition moment function R e ( r ) = 3.05 a.u. was fitted to previously reported relative absorption band strength measurements and the radiative lifetime of the A 1 Σ u + state. A numerical integration of ∫ ψ v ′ ∗ R e ( r ) ψ v ″ d r was performed in computing the Einstein coefficients and absorption band oscillator strengths, and these were found to differ negligibly from similar results obtained with the r-centroid approximation, as expected for a constant R e ( r ) function.

Spectra analysis of Yb: Y3Al5O12 crystals with different Yb doping concentration

Yb：Y3Al5O12(Yb:YAG) single crystals with Yb3+ doping level of 5.4at%, 16.3at%, 27.1at%, 53.6at%, and 100at% were grown by the Czochralski method. The effects of different Yb3+ doping level on the absorption spectra and fluorescence spectra were studied. The results showed that the real absorption coefficient of the absorption peaks increases linearly with the increasing of Yb3+ doping level in Yb:YAG crystals. Absorption band oscillator strengths of Yb：YAG crystals were calculated with Smakula formula and the effects of different Yb3+ doping level on the oscillator strengths were also studied. The concentration quenching of fluorescence was observed when the Yb3+ doping level reached 27.1at% in Yb:YAG crystals. The shape of fluorescence spectra of Yb:YAG could be significantly influenced when the Yb3+ doping level is higher than 53.6at%.

Oscillator strengths, Huang–Rhys parameters, and vibrational quantum energies of cerium-doped gadolinium oxyorthosilicate

Temperature-dependent optical absorption of cerium-doped gadolinium oxyorthosilicate (Gd2SiO5:Ce) has been measured and analyzed for impurity-ion-lattice coupling parameters and oscillator strengths. Although the spectrum consists of overlapping Ce3+ bands and Gd3+ lines, two well-resolved Ce3+ bands with 10 K maxima at 3.32 eV (peak a) and 3.61 eV (peak b) are amenable to spectral analysis. These bands, previously assigned to Ce3+ ions occupying crystallographically inequivalent substitutional sites, are characterized by Gaussian line shapes and temperature-dependent half widths that are well described by the linear model of impurity-ion-lattice coupling. Huang–Rhys [Proc. R. Soc. A 204, 404 (1950)] parameters of peaks a and b are 22.7 and 5.7, respectively, indicating strong ion-lattice coupling, with vibrational frequencies 1.83×1013 s−1 (peak a) and 5.07×1013 s−1 (peak b). Peak b centroid is approximately temperature independent, but peak a centroid shifts to higher energy with increasing temperature. This dependence is adequately described by including higher-order coupling terms in the ion-lattice interaction, although crystal-field contributions cannot be excluded. Absorption band oscillator strengths, f, are calculated from Smakula’s [Z. Phys. 59, 603 (1930)] formula and knowledge of cerium concentration for the two inequivalent sites. In the interval 10–300 K, peak a f values range from (9.8 to 26.8)×10−4 and peak b f values vary from (7.8 to 5.8)×10−3. From the known correlation between oscillator strength and metal-ion-ligand separation, we identify peaks a and b as the seven- and nine-oxygen-coordinated sites, respectively.

Absorption band oscillator strengths of N2 transitions between 95.8 and 99.4 nm

Photoabsorption cross sections for seven electric dipole-allowed N2 bands, at wavelengths between 95.8 and 99.4 nm, have been measured with an instrumental resolution of 6.2×10−4 nm. Integrated cross sections and band oscillator strengths are presented for the c4′ 1Σu+(v′=0)–X 1Σg′(v ″=0) and c3 1Πu(v′=0)–X 1Σg+(v″=0) transitions, as well as for five bands (v′=0,1,2,3,4) in the b 1Πu(v′)–X 1Σg+(0) progression. The results are compared with earlier, lower resolution absorption measurements, electron scattering measurements, and calculations based on a deperturbation analysis of the excited states.

Oscillator strengths of absorption bands of Pr3+, Nd3+, Eu3+, Er3+, and Yb3+ ions in A GaCl3-SOCl2 system

Oscillator strengths of absorption bands of Pr3+, Nd3+, Eu3+, Er3+, and Yb3+ ions in A GaCl3-SOCl2 system

Theoretical Electronic Transition Probabilities in Diatomic Molecules. I. Hydrides

Hartree–Fock (HF) electronic transition moments calculated in both the position and momentum representations are presented as a function of the internuclear separation R for the BeH, MgH, OH, and SH (A–X) systems. The vibrational averages of these quantities are obtained and the results are used to calculate some absorption band oscillator strengths. For the OH (A–X) system several independent experimental determinations of the 0–0 band oscillator strength have been reported in the literature. Our theoretical value of 20.6 × 10−4 differs from experiment by a factor of 2.5. Active electron and virtual orbital approximations to the HF transition moment integrals are given. Consideration of the united and separated atom limits and the region of the equilibrium internuclear separation for the states involved leads to an abbreviated discussion of the effect of correlation on the HF transition moments. HF transition moment calculations at a single value of R are also reported for the BH+, AlH+, HF+, and HCl+ (A–X) systems.

Oscillator Strength of Absorption Band in Dye Molecules

Oscillator Strength of Absorption Band in Dye Molecules