Calcium Vapor Research Articles

ChemInform Abstract: A New Method for Preparation of Organocalcium Halides by Cocondensation of Calcium Vapor with Solvents.

AbstractActivated calcium (II) is produced by cocondensation of the metal with solvents such as THF.

Investigation of quasi-cw lasing due to a self-terminating transition of the calcium atom in a hollow-cathode discharge

An investigation was made of the characteristics of lasing due to the self-terminating 4p1P1–3d1D2 transition of the calcium atom (λ = 5.544 μ) in a quasisteady-state hollow-cathode discharge. The maximum laser output power was 10.5 mW, the specific laser output power being not less than 30 mW/cm3. This was roughly a factor of 30 greater than the specific laser output power realized by exciting calcium vapor in the positive column of a discharge. The experimental results obtained were used to estimate the active-medium efficiency ηam = 0.21–0.59% and the gain κ≥0.36 cm−1.

A new method for preparation of organocalcium halides by cocondensation of calcium vapor with solvents

Calcium vapor (atom) when cocondensed with various solvents at 77 K was found to be very reactive toward alkyl and aryl halides. A series of organocalcium halides was prepared in good yields by addition of alkyl or aryl halides to the resultant calcium atom-solvent slurries at ambient temperatures.

Laser spectroscopy of strontium and calcium monoalkylamides

The reaction of strontium and calcium vapors with primary amines was studied in the gas phase. These reactions produce the metal monoalkylamides CaNHR and SrNHR. The C tilde/sup 2/A/sub 1/(/sup 2/A')-X tilde/sup 2/A/sub 1/(/sup 2/A'), B tilde/sup 2/B/sub 1/(/sup 2/A'')-X tilde/sup 2/A/sub 1/(/sup 2/A'), and A tilde/sup 2/B/sub 2/(/sup 2/A')-X tilde/sup 2/A/sub 1/(/sub 2/A') electronic transitions were observed by laser excitation spectroscopy. Some Ca-N and Sr-N stretching frequencies were assigned from the electron transitions.

ChemInform Abstract: Metal Cluster vs. Atom Reactivities. Calcium and Magnesium Vapor with Alkyl Halides and Methane

ChemInform Abstract: Metal Cluster vs. Atom Reactivities. Calcium and Magnesium Vapor with Alkyl Halides and Methane

Metal cluster vs. atom reactivities. Calcium and magnesium vapor with alkyl halides and methane

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMetal cluster vs. atom reactivities. Calcium and magnesium vapor with alkyl halides and methaneKenneth J. Klabunde and Alan. WhettenCite this: J. Am. Chem. Soc. 1986, 108, 21, 6529–6534Publication Date (Print):October 1, 1986Publication History Published online1 May 2002Published inissue 1 October 1986https://doi.org/10.1021/ja00281a014RIGHTS & PERMISSIONSArticle Views146Altmetric-Citations47LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (800 KB) Get e-Alerts Get e-Alerts

Metal vapors in gas tungsten arcs: part i. spectroscopy and monochromatic photography

Metal vapors in gas tungsten welding arcs were studied in order to determine the effects of these vapors on arc properties and subsequently on weld bead configuration. Emission spectroscopy and monochromatic photography were used to determine the prominent metal species present and their distribution in arcs on stainless steel. It was found that, in addition to the expected species (Fe, Mn, Cr), calcium and aluminum vapors were also detectable, although these elements were present in the base plate only at very low concentrations. All metal vapors were determined to be concentrated just above the weld pool in high current arcs, but were also detected in the upper regions of low current arcs. Aluminum, calcium, and sometimes thorium were found to vaporize from the tungsten electrode.

Saturated two-photon absorption by calcium atoms in a perturber bath

This study was performed with calcium vapor at about 750°C perturbed by He at densities between 0.5 x 10 19 and 5 x 10 19 atoms/cm 3 and under continuous laser intensities up to 10 kW/cm 2. The collisional absorption profile of the calcium intercombination line (657.5nm) has been obtained from fluorescence measurements and by using theoretical expressions. The saturation rates give the collisional decay rates of the atomic levels involved. The formation of exciplex species is suggested in order to interpret some of the experimental results.

The collisional quenching of Ca[4s3d(1D2)] by H2and D2over the temperature range 750–1100 K studied by time-resolved atomic emission at λ= 457.5 nm {Ca[4s3d(1D2)]→ Ca[4s2(1S0)]+hν} following pulsed dye-laser excitation

The collisional removal of Ca[4s3d(1D2)] by hydrogen and deuterium has been studied in the time-resolved mode in the temperature range 750–1100 K. Ca(4 1D2) was generated by pulsed dye-laser excitation of calcium vapour at λ= 457.5 nm {Ca[4s3d(1D2)]â†� Ca[4s2(1S0)]} and monitored by time-resolved forbidden atomic emission at the resonance wavelength using boxcar integration with computer interfacing. A limited number of observations was also made in emission at λ= 657.3 nm [Ca(4 3P1)→ Ca(4 1S0)+hν] arising from the removal of Ca(4 1D2) by energy pooling and emission of radiation to the states Ca(4 3P2,1). Absolute second-order rate constants for the collisional removal of Ca(4 1D2) by hydrogen and deuterium were determined for nine separate temperatures across the overall range, yielding the following Arrhenius forms: kH2=(5.5 ±1.00.9)× 10–10 exp(–14.4 ± 1.3 kJ mol–1)//RT cm3 molecule–1 s–1 and kD2=(3.9 ± 0.4)× 10–10 exp(–22.2 ± 0.8 kJ mol–1)//RT cm3 molecule–1 s–1.

Time-resolved emission studies of the collisional quenching of Ca(43PJ) and Sr(53PJ) by various gases in an equilibrium-coupled system following pulsed dye-laser excitation at λ= 657.3 nm [Ca(43P1)â†� Ca(41S0)

The collisional quenching of Ca(4 3PJ) and Sr(5 3PJ) has been studied for an equilibrium system coupled by the process Ca(4 3PJ)+ Sr(5 1S0)⇌ Ca(4 1S0)+ Sr(5 3PJ) and established following pulsed dye-laser excitation of Ca(4 1S0) to Ca(4 3P1) at λ= 657.3 nm in mixtures of calcium and strontium vapour in the presence of an excess of helium buffer gas and added quenching gases. Ca(4 3P1), Sr(5 3P1) and Sr(6 3S1) were monitored by time-resolved emission at λ= 657.3, 689.3 [Sr(5 3P1)→ Sr(5 1S0)+hν) and 679.1 nm [Sr(6 3S1)→ Sr(5 3P0)+hν], respectively, using boxcar integration. The measured first-order decay coefficients for Ca(4 3PJ) and Sr(5 3PJ) under equilibrium-coupled conditions were found to be in quantitative agreement with previously measured values of absolute second-order rate constants for the quenching gases Kr, Xe, H2, D2, N2, CO, NO, N2O, CO2, NH3, CH4, CF4, C2H2, C2H4 and C6H6, obtained using the present system, employing signal averaging, on decays of Ca(4 3PJ) and Sr(5 3PJ) individually. Finally, energy pooling according to the processes Ca(4 3PJ)+ Sr(5 3PJ)→ Sr(6 3S1)+ Ca(4 1S0), Sr(5 3PJ)Sr(5 3PJ)→ Sr(6 3S1)+ Sr(5 1S0) was investigated quantitatively from measurements at λ= 679.1 nm in the time domain and in the presence of the quenching gases.

カルシウム飽和蒸気によるチタン脱酸限界と酸化チタンの還元に関する研究

カルシウム飽和蒸気によるチタン脱酸限界と酸化チタンの還元に関する研究

Collisional quenching of Ca(43PJ) by H2and D2studied over the temperature range 850–1075 K by time-resolved atomic resonance emission at λ= 657.3 nm [Ca(43P1)→ Ca(41S0)+hν] following pulsed dye-laser excitation

We present a kinetic study of the collisional behaviour of Ca(4 3PJ), 1.888 eV above the 4 1S0 ground state, with hydrogen and deuterium over the temperature range 850–1075 K. Ca(4 3P1) was optically excited by repetitive pulsed dye-laser excitation at λ= 657.3 nm of calcium vapour in equilibrium with the solid at elevated temperatures in a slow-flow system, kinetically equivalent to a static system. Following rapid Boltzmann equilibration within the 4 3PJ spin–orbit manifold, the time-resolved emission at λ= 657.3 nm [Ca(4 3P1)→ Ca(4 1S0)+hν] was monitored photoelectrically using a boxcar integrator interfaced to a microcomputer for kinetic analysis of the atomic emission data in digital form. Absolute second-order rate constants for collisional quenching of Ca(4 3PJ) were determined at ten different temperatures in the range 850–1075 K yielding the following Arrhenius forms: k[Ca(4 3PJ)+H2]/cm3 molecule–1 s–1=[graphic omitted] × 10–9 exp[(–88.3±4.2 kJ mol–1)/RT], k[Ca(4 3PJ)+D2]/cm3 molecule–1 s–1=[graphic omitted] × 10–9 exp [(–92.9±5.0 kJ mol–1)/RT] and constituting the first temperature-dependent investigation for these processes. In both cases the rate data were also fitted to a three-parameter equation of the form kQ=B+A exp (–E/RT). The term B, which may be attributed to physical quenching, was found to be negligible in magnitude compared with the temperature-dependent term. The experimental activation energies were found to be in accord with reaction endothermicities to yield CaH and CaD (X2Σ+, ν″= 0) and the pre-exponential factors with calculated collision numbers. The results are compared with analogous rate data reported by other workers on the temperature-dependence of the quenching of Mg(33PJ) by hydrogen and deuterium. Finally, an investigation of the temperature-dependence of the diffusion of Ca(4 3PJ) in helium is presented in which the diffusion coefficient D[Ca(43PJ)+ He] is found to satisfy a temperature dependence of T1.8±0.04.

The stimulated emissions and the collision processes in atomic calcium vapor excited by two photons

Abstract When a pulsed nitrogen laser pumped dye laser was tuned to the two-photon resonant excitation of atomic calcium, laser action was observed at the wavelengths 585.7, 646.0, 671.7, 714.8 nm and 2.06, 2.5 μm. The resonant two-photon excitation, the multiphoton ionization spectroscopy for detecting the two-photon excitation processes, and the collision induced spin change energy transfer process are discussed.

Kinetic study of Ca(43PJ) by time-resolved emission, 43P1→ 41S0+hν(λ= 657.3 nm), following dye-laser excitation. Spontaneous emission, diffusion and collisional quenching

We present a kinetic study of the low-lying electronically excited state of atomic calcium, Ca[4s4p(3PJ)], 1.885 eV above the 4s2(1S0) ground state. Ca(4 3P1) was generated by dye-laser pulsed excitation at λ= 657.3 nm of calcium vapour [Ca(4 3P1)â†� Ca(4 1S0)] at elevated temperatures (1000 K), in equilibrium with solid calcium, in a slow-flow system, kinetically equivalent to a static system. Following rapid Boltzmann equilibration within Ca(4 3PJ) through collisions, the forbidden time-resolved atomic resonance fluorescence at the same wavelength was monitored using boxcar integration. The decay of Ca(4 3PJ) in the presence of all the noble gases, He, Ne, Ar, Kr and Xe, was studied, yielding measurements of relative diffusion coefficients. Extrapolation of the diffusional component of the decay in each noble gas to infinite pressure yields an independent value of the mean radiative lifetime for Ca(4 3P1)→ Ca(4 1S0)+hν(λ= 657.3 nm), the average of which from the measurements in all the noble gases yields τe= 0.34 ± 0.02 ms (error 2σ). This result is compared with values reported from previous measurements, particularly atomic beams and time-resolved measurements. The kinetic analysis also gives rise to data for the collisional quenching of Ca(4 3PJ), which is found to be insignificant for most of the noble gases [kHe,Ne,Ar,Kr⩽ 4 × 10–15 cm3 molecule–1 s–1(1000 K)], in contrast to measurements from earlier work using phase-shift techniques. Xenon, however, exhibited measurable rates of collisional quenching of Ca(4 3PJ) characterised by kXe= 2.4 ± 0.3 × 10–14 cm3 molecule–1 s–1(1000 K). The time-resolved emission technique is further applied to the study of the removal of Ca(4 3PJ) by added gases, for which we report (errors 1σ)kN2=(8.9 ± 0.9)× 10–13 cm3 molecule–1 s–1(1000 K), kH2=(6.0 ± 0.6)× 10–14 cm3 molecule–1 s–1(1000 K), kD2=(2.7 ± 0.3)× 10–14 cm3 molecule–1 s–1(1000 K).

Collisional quenching of Ca(43PJ) studied by time-resolved emission, 43P1→ 41S0+hν(λ= 657.3 nm), following dye-laser excitation

We present a study of the collisional quenching of electronically excited calcium atoms, Ca[4s4p(3PJ)], 1.885 eV above the 4s2(1S0) ground state, by a range of added gases. Ca(4 3P1) was generated by repetitive pulsed dye-laser excitation at λ= 657.3 nm [Ca(4 3P1)â†� Ca(4 1S0)] of calcium vapour in equilibrium with solid calcium at elevated temperatures (1000 K) in a slow flow system, kinetically equivalent to a static system. Following rapid Boltzmann equilibration within the 4 3PJ manifold, the time-resolved forbidden emission, 4 3P1→ 4 1S0+hν(λ= 657.3 nm), was monitored in the presence of added gases using ‘pre-trigger photomultiplier gating’ and boxcar integration. The following absolute second-order quenching constants (kQ/cm3 molecule–1 s–1, 1000 K, errors 1σ) are reported: CO, 3.7 ± 0.5 × 10–13; NO, 3.2 ± 0.3 × 10–13; CO2, 3.1 ± 0.3 × 10–13; N2O, 6.5 ± 0.5 × 10–13; NH3, 2.5 ± 0.3 × 10–13; CH4, 5.4 ± 0.4 × 10–13; CF4, 1.9 ± 0.2 × 10–13; C2H2, 1.4 ± 0.2 × 10–13; C2H4, 2.3 ± 0.3 × 10–13; C6H6, 6.0 ± 0.2 × 10–12. Where possible these data are compared with those derived from other decay measurements in which Ca(4 3PJ) was generated by dye-laser excitation and monitored either via time-resolved atomic resonance absorption spectroscopy or by phase-shift techniques. The absolute rate constants are compared with analogous data for Mg(3 3PJ)(2.71 eV) and discussed, where appropriate, in terms of orbital correlation and in relation to data from atomic beams which describe chemiluminescence from product states.

Collisional effects and two-photon absorption in calcium vapour

Experiments on collisionally assisted two-photon absorption (TPA) in calcium vapour buffered by argon gas have been performed using two tunable dye lasers. Both direct TPA and stepwise transitions through the collisionally populated resonance level. 4s4p 1P1, have been observed. Detailed study of the lineshapes of the stepwise transitions to the 4p2 1S0, 4p2 1D2 and 4s6s 1S0 levels reveals large differences in the strengths of the Ca-Ar interatomic potentials for these levels. These differences probably arise from configuration mixing.

D−production by charge transfer of (0.3 - 3)-keVD+in thick alkaline-earth vapor targets: Interaction energies forCaH+, CaH, andCaH−

Equilibrium charge-state fractions of energetic deuterium ions and atoms emerging from alkaline-earth (magnesium, calcium, strontium, and barium) vapor targets are reported in the range of 0.3- to 3-keV incident ${\mathrm{D}}^{+}$ energy. Deuterium negative-ion production in thick barium and calcium vapor targets equals similar production in cesium vapor (\ensuremath{\sim}34%). Moreover, the maxium ${\mathrm{D}}^{\ensuremath{-}}$ production in strontium vapor exceeds that for all other known gas or vapor targets and reaches 50% at 500 eV. Theory does not quantitatively describe these results, although ab initio molecular-interaction-energy calculations on the neutral and negative-ion CaH systems lead to the prediction of large ${\mathrm{D}}^{\ensuremath{-}}$ yields at low energies. The theoretical prediction is based on the lack of a strong coupling between the negativeion and neutral molecular states. This implies that there are small ${\mathrm{D}}^{\ensuremath{-}}$ electron-detachment cross sections at energies less than 1 keV. The present measurements agree with previous measurements done at higher energies.

Tunable dye laser spectroscopy of atomic calcium: collisional redistribution of radiation

By tuning a pulsed dye laser through the resonance line of calcium at 422.7 nm the authors have investigated the spectral redistribution of laser radiation by calcium vapour. Two main components were resolved in the side emission from an oven containing calcium vapour and argon buffer gas. These are produced by Rayleigh scattering and by collision-induced fluorescence. The intensity of the Rayleigh component was found to vary as Delta -2 where Delta = omega 21- omega L is the laser detuning from resonance. In contrast the intensity of the collision-induced fluorescence showed a markedly asymmetric dependence on detuning. Detailed studies of the collision-induced fluorescence have enabled the complete line shape of the calcium resonance line perturbed by argon to be determined. The interpretation of this data in terms of a frequency-dependent collision rate, gamma E( Delta ), is discussed. This paper also reports calculations of theoretical line profiles using the unified Franck-Condon theory and trial interatomic difference potentials. The comparison of the experimental and theoretical line profiles enables the range of validity of the unified Franck-Condon theory to be assessed and the form of the optimum Ca-Ar difference potential to be selected.

Resonant generation of the second harmonic in calcium vapor

Strong resonant generation of the second harmonic by means of a transition forbidden in the electric-dipole, quadrupole, and magnetic-dipole approximations, was observed in the absence of external static electric and magnetic fields.

Efficient up-conversion of the frequency of neodymium laser radiation to the visible range in calcium vapor

Neodymium laser radiation of 0.1 W power was converted efficiently from λ = 1.06 μ to the visible wavelength λ =418 nm using a resonant four-photon parametric process in calcium vapor. The power conversion efficiency was ~2%.