CW laser oscillation on transitions of Tl+ in a hollow-cathode Ne-Tl-halide discharge

CW laser oscillation on Tl⁺ transitions (594.9 nm and 695.1 nm) at low operating temperatures is obtained. As a source of Tl atoms the volatile salt TlCl is used. The compound is evaporated due to selfheating by the discharge current. Maximum laser intensity is obtained at neon pressure of 10–13 Torr and cathode temperature ≈ 320°C.     

CW laser oscillation on transitions of As+ in He-AsH3 gas discharges

Operation of a cw arsenic ion (As⁺) laser using the gaseous arsenic trihydride, AsH₃, as a free arsenic donor in hollow-cathode He-AsH₃ discharges is reported. Optimum conditions of the gas mixture are set by simple gas handling techniques at room temperature. Laser performance compares favourably with that obtained with the He-As laser.     

New cascade laser transitions in CH2F2 pumped with the 9R32 line of a cw CO2 laser

New cascade laser transitions of¹²CH₂F₂ at 172.50m, 208.83m, 220.44m, 223.99m and 250.61m are reported. A waveguide FIR laser was pumped with a quasi cw¹²C¹⁶O₂ laser operating on the 9R32 line. Together with the already known lines at 184.3m, 196.1m and 235.9m, the laser lines can be assigned to rotational transitions in the ₉ vibrational band of¹²CH₂F₂ and to refill transitions of the vibrational ground state ₀.     

Emission cross sections for the laser lines of I+ by electron-I2-molecule collisions

We have measured the emission cross sections for the fifteen spectral lines of I⁺ by single electron impact on I₂ molecules, which include the laser lines of the positive column He-I⁺ laser. The measured values are of the order of 10^-19 to 10^-20 cm².     

Study of simultaneous oscillation on several transitions in cw CO laser

Received: 13 September 1995/Revised version: 5 August 1996     

Tunable room-temperature cw laser action in Cr3+: GdScAl-garnet

We report, for the first time, cw room temperature laser action of Cr³⁺:Gd₃Sc₂Al₃O₁₂. These crystals show a strong band fluorescence due to the ${}^4\text{T}{}_2\text{→}{}^4\text{A}{}_2$ transition with a lifetime of 150 μs. Laser pumping in the blue and red spectral range yields a minimum threshold of 170 mW and slope efficiencies up to 18.5%. The emission of the free running laser is centered at 784 nm with a FWHW of 5 nm. The extension of the Ga-garnets to Al-garnets as suitable host lattices for Cr³⁺ reveals the variety of garnet-structured crystals having an appropriate ligand field for continuously tunable laser operation.     

ESR detection of pressure-induced structural change around Pb2+ and Cd2+ in soda borate glasses

The pressure-induced changes in the coordination structure of Cd²⁺ and Pb²⁺ were examined by measuring the ESR spectra of γ-ray-induced Cd⁺ and Pb³⁺ centers. The s-character of the magnetic electron in the centers increased on densification and was estimated from the analysis of the hyperfine absorption due to a ²⁰⁷Pb³⁺ and ¹¹¹Cd⁺ and ¹¹³Cd⁺. The increase in the s-character means that the strength of both Pb²⁺O and Cd²⁺O bonds was reduced upon densification and that the coordination number of Cd²⁺ and Pb²⁺ increased. The coordination sphere of Cd²⁺, which responds more sensitively than that of Pb²⁺ to the change in chemical environments, was more heavily compressed than that of Pb²⁺.     

Mn2+ paramagnetic resonance and structural phase transitions in Rb2CdCl4

Structural phase transition in Rb₂CdCl₄: Mn²⁺ single crystal has been found near 133 K by EPR, X-ray and optical methods. Octahedral tilt system in the low temperature phase corresponds to the symmetry change D¹⁷_4h → D¹⁸_2h or D¹⁷_4h → C⁶_2h.     

Opto-voltaic representation of a gain profile in a cw CO2 laser

An opto-voltaic signal is investigated experimentally in a cw CO₂ laser equipped with a coupling-out hole mirror. It is shown that the opto-voltaic signal and the output laser power can be uncorrelated.     

Vibronic laser action of V2+:CsCaF3

CW laser operation has been achieved with the vibronic solid-state material V²⁺:CsCaF₃ at 80 K. The laser is tunable between 1.24 and 1.33 μm with a potential long wavelength extension.     

Activation and cleaning of oxide surfaces by a cw CO2 laser

Silica, alumina, and zinc oxide surfaces have been dehydroxylated by a cw CO₂ laser. Three to seven W/cm² produce the same surfaces spectroscopically as does heating at 400–1000°C. Varying the laser power while keeping the total number of photons constant shows that this is not a linear photochemical process and may be purely thermal desorption. Laser heating has a number of practical advantages over traditional heating methods which have been used for surface cleaning and activation.     

Transition moment variation in the A2Σ+ → X2Πi transition of HCl+, DCl+ and HBr+

Relative emission intensities of sixteen bands of HCl⁺ (A²Σ⁺ - X²Π_i), four bands of DCl⁺ (A²Σ⁺ - X²Π_i), and 5 bands of HBr⁺ (A²Σ - X²Π_i) have been made using both ion-beam excitation and microwave discharge sources. Intensities were determined by comparison with computer-generated spectra. Treatment of the data within the r-centroid approximation shows that in HCl⁺ the electronic transition moment decreases strongly at large $\text{r}{}_{\mathrm{v\prime v″}}$ [$\text{Re}\text{α}\text{exp}\text{(?3.6}\text{r}{}_{\mathrm{v\prime v″}}\text{)}\text{for 1.44}\text{A}\text{?}\text{< r}{}_{\mathrm{v\prime v″}}\text{< 1.82}\text{A}\text{?}$] but levels off at shorter $\text{r}{}_{\mathrm{v\prime v″}}$. DCl⁺ data agree quantitatively with HCl⁺. The variation in the HBr⁺ moment is similar, with $\text{R}\text{e}\text{α}\text{exp}\text{[?4.5}\text{r}{}_{\mathrm{v\prime v″}}\text{]}\text{for 1.58}\text{A}\text{?}\text{<}\text{r}{}_{\mathrm{v\prime v″}}\text{< 1.78}\text{A}\text{?}$.     

Infrared electronic transitions of Eu+3 in GdAlO3

Infrared ⁷F_O → ⁷F_J electronic transitions are reported for Eu⁺³ in GdAlO₃. The low symmetry of the crystalline field allows the observation, for the first time, of transitions with J = 3, 4, 5 and 6. The spectra are explained by means of a crystal-field model where a C_s term is added as a perturbation to the cubic field in order to take into account the lattice distortion. This model predicts energy levels which are in good agreement with the experimental data.     

Ni2+ emission in SrF2

Luminescence measurements of X-irradiated SrF₂:Ni are reported. After X-irradiation two emission bands have been found. One of them peaked at 293 nm and has an excitation band at 267 nm. The other one at about 770 nm, which is much weaker, has an excitation band at 274 nm. Both emission bands are also observed under X-ray excitation. A comparison with some previous studies of the absorption and thermoluminescence properties of X-irradiated SrF₂:Ni indicates that the emission bands are due to two different kinds of Ni²⁺ centers. The proposed emission mechanisms are similar to those found in CaF₂:Ni.     

ESR of Fe3+ -Rhombic,Fe2+ -Vo and Fe1+ -Vo complexes in SrTiO3

Three new Fe-defect complexes have been identified by ESR in Fe doped crystals of SrTiO₃. These are an Fe³⁺ center with rhombic fine structure in the “as-grown” crystals, and the vacancy associated complexes Fe²⁺ -V_o and Fe¹⁺ -V_o in “reduced” crystals. Photo-excited charge transfer effects are observed for these centers.     

The origin of K2, Rb2 and Cs2 triplet 13Πg−X3Σ+u bands in discharge

The absorption and emission spectra of potassium, rubidium and caesium low-pressure discharges have been studied at the far blue wings of resonance D2-lines. The observed diffuse bands were attributed to the 1³Π_g?X³Σ⁺_u transition. Experiments revealed the recombination ²P + ²S nature of these bands, and the corresponding rate coefficients were obtained. Energies of the higher excited states as well as the X³Σ⁺_u -state well depths for K₂, Rb₂ and Cs₂ molecules were estimated.     

Collision-induced simultaneous transitions in H2+CF4 and H2+SF6 mixtures

The simultaneous transitions of the v₃ fundamental vibrations of CF₄ and SF₆ with the fundamental Q branch and S(1) line of H₂ have been studied for various H₂+CF₄ and H₂+SF₆ mixtures at total pressures up to 185 bars. The integrated intensities are found to be proportional to the partial densities of the gas mixture components. The agreement between experimental and calculated intensities is generally better for the Kihara potential than for the Lennard-Jones potential.     

Modes of a Ne-H2 laser employing a hollow-cathode discharge

An Ne-H₂ laser employing the 2s-2p transition in Ne is examined at current densities up to 300 ma/cm². The H₂ removes metastable Ne atoms and reduces the rate of excitation of the 2p level, so the discharge currents may be raised considerably. The gain at 11 143 Å is measured as a function of discharge current for near-optimal conditions.