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Showing papers on "Buffer gas published in 1977"


Journal ArticleDOI
TL;DR: Using a pulsed tunable dye laser either of the 6s6p 1P10, 5d6p 3D10 or 5d 6p 3Pd10 levels in Ba I could be selectively excited from the ground state.
Abstract: Using a pulsed tunable dye laser either of the 6s6p 1P10, 5d6p 3D10 or 5d6p 3Pd10 levels in Ba I could be selectively excited from the 6s2 1S0 ground state. A simultaneously pumped broad-band dye laser provided a back-ground continuum for photographic registration of absorption spectra. By quantum defect analysis, series members and perturbing terms of 6sns 1S0 were extended from n=9 to n=31, of 6snd 1D2, from n=41 to n=52, and of 6snd 3D2, from n=11 to n=28. In addition, a change of previous assignments is suggested for 6p2, 8s, 9s 1S0 and 10d, 11d 3D2. Argon or neon was used as a buffer gas. For lines going to levels with high quantum numbers (n>or approximately=12), argon gave a pressure shift to the red of about 0.3 cm-1 per 100 Torr and neon a blue-shift of about 0.015 cm-1 per 100 Torr.

54 citations


Journal ArticleDOI
TL;DR: In this paper, laser-induced fluorescence measurements of the initial product state distributions of CN(X2 Sigma +) produced during the photolysis of C2N2 at a wavelength of 160 nm.
Abstract: The paper reports laser-induced fluorescence measurements of the initial product state distributions of CN(X2 Sigma +) produced during the photolysis of C2N2 at a wavelength of 160 nm. The parent molecules were photodissociated by an argon flash lamp, and saturated solutions of BBD in p-dioxane were used as a laser dye to produce radiation that excited CN radicals in the (upsilon-double-prime, N-prime) vibrational-rotational sublevels of the X state to the B-state sublevels. Spectral-line identification is discussed along with the observed rotational, electronic, and vibrational energy partitionings. The effect of added buffer gas (N2 or He) on the observed product state distributions is examined in order to monitor collisional energy transfer from CN(A2 Pi, upsilon = 0) to CN(X2 Sigma +, upsilon-double-prime = 4). It is found that both buffer gases produce population inversion between the upsilon-double-prime = 4 and upsilon-double-prime = 3 levels of the X state.

52 citations


Patent
25 Nov 1977
TL;DR: A high pressure electric arc tube discharge lamp utilizing low power input is described in this paper, where the arc tube is of isothermal design and the electrode spacing is less than 20 mm and the arc is electrode-stabilized.
Abstract: A high pressure electric arc tube discharge lamp utilizing low power input.he electrode spacing is less than 20 mm and the arc is electrode-stabilized. The arc tube is of isothermal design. The gas fill of the lamp contains a mixture of metal (i) iodides or (ii) iodides and bromides. The metal halides must include at least the halides of sodium and tin. Mercury is preferred as the buffer gas. When operating, the lamp has a low-color temperature, a luminous efficacy of 80 lms/W and a color-rendering index of about 75. It is suitable for use in interior lighting.

36 citations


Patent
23 Sep 1977
TL;DR: In this paper, a high power gas dynamic mixing laser capable of having an energizing gas formed by an exothermic decomposition process is described, which includes a housing having a reaction chamber in which an excitation gas is formed by thermal decomposition of a starting material.
Abstract: A high power gas dynamic mixing laser capable of having an energizing gas formed by an exothermic decomposition process is disclosed. The laser includes a housing having a reaction chamber in which an excitation gas is formed by thermal decomposition of a starting material, a nozzle connected to the housing for expanding the excitation gas to supersonic velocity, means for injecting a lasing gas into the supersonic stream of excitation gas to produce an inversion of populated energy levels of the lasing gas, optical means for extracting a laser beam and exhaust means for passing the gas mixture to the atmosphere. An embodiment of the present invention includes a return duct attached at one end to the exhaust means and at the other end to the housing for circulating the gas through the laser and a lasing gas capable of thermal decomposition downstream the optical means to form the excitation gas.

22 citations


Patent
08 Jun 1977
TL;DR: In this paper, the authors describe a heating method and apparatus which involves burning an air-gas mixture whose combustion is promoted by the action of two kinds of catalyzers to convert an air gas mixture to a high-temperature thermal energy for soldering, desoldering, cutting and other similar processes.
Abstract: A heating method and apparatus which involves burning an air-gas mixture whose combustion is promoted by the action of two kinds of catalyzers to be converted to a high-temperature thermal energy for soldering, desoldering, cutting and other similar processes. A controlled amount of liquefied gas from a gas container is electrically ignited and burned by the catalysis action in a combustion chamber, and the converted flameless thermal energy is conducted through a heat conductor, concentrating a high-temperature heat on the tip of the conductor. The gas used usually includes liquefied hydrocarbons such as petroleum oil gas, natural gas, manufactured gas, propane gas and the like.

21 citations


Patent
14 Mar 1977
TL;DR: In this article, a high pressure sodium vapor discharge lamp with an alumina tube envelope containing sodium, an inert starting gas, a mercury or cadmium buffer gas source and a pair of discharge electrodes is described.
Abstract: HIGH PRESSURE SODIUM VAPOR DISCHARGE LAMP Abstract of the Disclosure The specification discloses a high pressure sodium vapor discharge lamp comprising an alumina tube envelope containing sodium, an inert starting gas, a mercury or cadmium buffer gas source and a pair of discharge electrodes. The inner diameter d in mm of the tubular envelope and the average potential gradient E in volt/cm has the following relationship: E ? 37.7-2.05d. The lamp further comprises a radiation suppressing means at least partially surrounding the tube envelope for selectively, and at least partially, absorbing red radiation having wavelengths longer than 620 nm. The lamp achieves a higher color temperature and a higher general color rendering index than conventional lamps of this type without an undesirable increase in the tube voltage, and is suitable for highly efficient indoor illumination.

20 citations


Journal ArticleDOI
TL;DR: In this article, the output powers for optimum temperature, buffer gas pressure, and delay time were found to be in the ratio P CuCl, CuBr, and CuI = 6 : 3 : 2.
Abstract: CuCl, CuBr, and CuI have been compared in a fixed parameter system as lasants for copper-vapor lasers. The output powers for optimum temperature, buffer gas pressure, and delay time were found to be in the ratio P CuBr :P CuCl :P CuI = 6 : 3 : 2.

19 citations


Journal ArticleDOI
TL;DR: In this article, the buffer gas of a double-pulse CuCl laser was added to the buffer to increase the production of copper atoms in the ground state, and a maximum laser energy increase of 15% was observed and the span of delay times for which laser action occurred increased.
Abstract: Addition of small amounts of hydrogen chloride to the buffer gas of a double-pulse CuCl laser causes an increase in the production of copper atoms in the ground state. A maximum laser energy increase of 15% was observed and the span of delay times for which laser action occurred increased.

18 citations


Journal ArticleDOI
TL;DR: The vibrational structure of the C 1 Π state of the NaK molecule, excited by laser radiation, was detected observing the atomic potassium fluorescent D-lines that result from the dissociation of the molecule in collisions with a buffer gas as discussed by the authors.

17 citations


Journal ArticleDOI
TL;DR: In this paper, the authors observed five laser transitions in the 358-747nm region, all of which originate from excited energy levels of singly ionized aluminum, and the excitation mechanism was thought to be a Ne+Al charge transfer reaction.
Abstract: We have observed five laser transitions in the 358–747‐nm region, all of which originate from excited energy levels of singly ionized aluminum. Laser action was obtained by exciting a neon buffer gas in an aluminum hollow cathode and the excitation mechanism is thought to be a Ne+‐Al charge transfer reaction. Single‐line output power on the 358‐nm laser transition of Al II was 9 mW, while multiline infrared output was 5 mW.

16 citations


Journal ArticleDOI
TL;DR: In this article, the energy transfer mechanisms for electron beam excited N • 92 dye vapor in various buffer gas mixtures have been examined and the optimum conditions for achieving intense dye vapor fluorescence with short duration electron pulse excitation are reported.
Abstract: The energy transfer mechanisms for electron beam excited N‐92 dye vapor in various buffer gas mixtures have been examined. Optimum conditions for achieving intense dye vapor fluorescence with short duration electron pulse excitation are reported.

Patent
06 May 1977
TL;DR: In this article, a discharge is produced by means of an electron beam and an electric field, and the discharge resulting from the application of the electric field heats secondary electrons produced by the electron beam to an energy level sufficient to make excited states.
Abstract: Apparatus for and method of operating a laser wherein a discharge is produced preferably in a high pressure lasing gaseous mixture comprising at least one suitable first gaseous species capable of providing an excited state which has a finite probability of being ionized and a molecular second gaseous species having a capability for attaching electrons to form negative ions. The gaseous mixture may, for example, comprise argon, neon, helium, xenon, krypton or a metal vapor such as mercury as the first species and, for example, hydrogen iodide, carbon tetrachloride, bromine, iodine or fluorine as the second species. A buffer gas such as, for example, argon, helium or neon may also be used. The discharge is produced by means of an electron beam and an electric field. The discharge resulting from the application of the electric field heats secondary electrons produced by the electron beam to an energy level sufficient to make excited states. Thus, for a mixture comprising argon, krypton and fluorine, for example, the heated secondary electrons pump at least some of the argon and the krypton to the metastable state. The excited argon transfers energy to the krypton to form additional excited krypton which, in turn, reacts with the fluorine to form excited krypton fluoride molecules. The krypton fluoride then dissociates or decays upon the emission of spontaneous or stimulated radiation. At power input levels where the electron density remains constant in time for a constant electric field, efficient discharge pumping of the excited states is provided when the fractional excited state population is kept small. Stable discharge operation is achieved when the lasing mixture contains an amount of the second species gas sufficient to provide an attachment rate n times the equilibrium ionization rate where n is the number of electron excitations which causes ionization of the first species.

Journal ArticleDOI
TL;DR: In this paper, an equilibrium calculation for the vapour growth of GaAs in an inert gas-hydrogen mixed carrier system is described, and the partial pressures of gaseous and gallium containing-species in equilibrium with GaAs are calculated for temperatures, chlorine to carrier gas mole ratios and mole fractions of hydrogen relative to the inert gas.
Abstract: An equilibrium calculation for the vapour growth of GaAs in an inert gas-hydrogen mixed carrier system is described. The partial pressures of gaseous- and gallium containing-species in equilibrium with GaAs are calculated for temperatures, chlorine to carrier gas mole ratios and mole fractions of hydrogen relative to the inert gas. It is shown that the general feature of the equilibrium pressures of the reactants for the inert gas- and inert gas-hydrogen mixed-carrier systems is similar to that of a hydrogen carrier system, and that GaAs tends to vaporize into the gas phase with the increase of the mole fraction of the inert gas. An application of the analysis to the vapour growth of GaAs with H2 introduction is discussed.

Journal ArticleDOI
TL;DR: In this paper, a transverse electrical discharge was used to produce a 100 nsec fwhm laser emission from the 5 2 P 1 2 → 5 2P 3 2 atomic iodine transition.

Patent
25 Apr 1977
TL;DR: In this paper, a carrier gas is injected with the trace gas ions into a vacuum chamber, the walls of which are cooled to cryopump the reagent gas and thus strip it away from the traces.
Abstract: A method of analyzing a trace gas, in which the trace gas is transported in a carrier gas stream into a reaction chamber where the trace gas is ionized. The carrier gas includes or is a reagent gas which is ionized in the reaction chamber and the ions of which in turn form trace gas ions. The carrier gas, which is cryopumpable, is then injected with the trace gas ions into a vacuum chamber, the walls of which are cooled to cryopump the reagent gas and thus strip it away from the trace gas ions. The trace gas ions are focussed into an analyzer and analyzed.

Patent
23 Nov 1977
TL;DR: A method of producing a single crystal of lithium tantalate in a platinum-rhodium crucible containing 20 to 40% by weight of rhodium in an atmosphere of reducing or inert gas is described in this paper.
Abstract: A method of producing a single crystal of lithium tantalate in a platinum-rhodium crucible containing 20 to 40% by weight of rhodium in an atmosphere of reducing or inert gas.

Patent
16 Feb 1977

Journal ArticleDOI
TL;DR: In this article, the rate constants of quenching of the fluorescence of POPOP, PPF, and PT vapors by oxygen were determined, and the addition of a buffer gas (SF6) to POPOP vapor increased the efficiency.
Abstract: Quantum efficiency η was determined for the fluorescence emitted from six dye vapors. The rate constants of the quenching of the fluorescence of POPOP, PPF, and PT vapors by oxygen were determined. The addition of a buffer gas (SF6) to POPOP vapor increased the efficiency η. The mechanism of quenching of the triplet POPOP molecules by the dye itself was analyzed.

Journal ArticleDOI
TL;DR: In this article, a mechanism for increased intensity was proposed, where the heavier support gas ionizes readily to a higher charge state, providing increased cathode heating, and the increased heating permits a reduction in primary gas flow (lower pressure) and subsequent beam increase.
Abstract: Experiments on mixing an easily ionized support gas with the primary ion source gas have produced large beam enhancements for high charge state light ions (masses ? 20). In the Oak Ridge Isochronous Cyclotron (ORIC), the beam increase has been a factor of 5 or greater, depending on ion species and charge state. Approximately 0.1 cc/min of the easily ionized support gas (argon, krypton, or xenon) is supplied to the ion source through a separate gas line and the primary gas flow is reduced by ? 30%. The proposed mechanism for increased intensity is as follows: The heavier support gas ionizes readily to a higher charge state, providing increased cathode heating. The increased heating permits a reduction in primary gas flow (lower pressure) and the subsequent beam increase.

Journal ArticleDOI
TL;DR: Stimulated emission as a result of selfterminating transitions in the copper atom was observed in discharges in copper chloride and iodide Pairs of discharge pulses were applied to a quartz tube with a heated zone 400 mm long and 20 pairs of electrodes Neon was used as the buffer gas as mentioned in this paper.
Abstract: Stimulated emission as a result of self-terminating transitions in the copper atom was observed in discharges in copper chloride and iodide Pairs of discharge pulses were applied to a quartz tube with a heated zone 400 mm long and 20 pairs of electrodes Neon was used as the buffer gas The dependence of the peak output power on the separation in each pair of pulses was determined The specific energy output per pulse was 50 muJ/cm/sup 3/ for CuCl and 40 muJ/cm/sup 3/ for CuI; these values were higher than those obtained by other authors in transverse discharges

Patent
22 Aug 1977
TL;DR: In this article, the disclosed laser employs a working gas comprising ammonia and a buffer gas which is chemically non-reactive with ammonia, and irradiates the working gas to excite ammonia molecules from the symmetric ground state to the anti-symmetric ν2 = 1 vibrational manifold.
Abstract: The disclosed laser employs a working gas comprising ammonia and a buffer gas which is chemically non-reactive with ammonia. A pumping laser beam at a wavelength of 9.2 μm, provided by a carbon dioxide laser tuner to the R(30) transition of the 001-020 band, irradiates the working gas to excite ammonia molecules from the symmetric ground state to the anti-symmetric ν2 =1 vibrational manifold. Collisions with buffer gas molecules cause the excited ammonia molecules to undergo intra-molecular energy transfer to a plurality of energy levels in the symmetric ν2 =1 vibrational manifold. Laser oscillation is achieved simultaneously on a plurality of ν2 =1 to ground transitions in the wavelength range extending from about 9.3 μm to about 13.8 μm.

Patent
21 Oct 1977

Patent
22 Apr 1977

Journal ArticleDOI
TL;DR: In this article, a single isolated saturated absorption feature in 127I2 using the optically pumped 5461nm Hg laser has been observed with low (∼6 MHz) resolution.
Abstract: A single isolated saturated‐absorption feature in 127I2 using the optically pumped 5461‐nm Hg laser has been observed with low (∼6 MHz) resolution The 3S1→3P2 Hg laser transition can be centered exactly on this feature by varying the N2 buffer gas pressure using the measured pressure tuning rate of −94 MHz/Torr This may provide an attractive laser system for absolute wavelength stabilization


Patent
05 Sep 1977

Book ChapterDOI
01 Jan 1977
TL;DR: In this paper, the authors proposed a buffer gas technique for non-resonant mixing processes, but it requires a highly uniform gas mixture and introduces additional absorption due to pressure broadening.
Abstract: Recently, 4-wave sum and difference frequency mixing processes in gases and vapors have received considerable attention as possible sources of tunable, coherent radiation in new regions of the electromagnetic spectrum [1]. The efficiencies of these processes have previously been enhanced either by phasematching by addition of a buffer gas of compensating dispersion or by two-photon resonant enhancement of the nonlinear susceptibility. The buffer gas technique works well for nonresonant mixing processes, but has the disadvantages of requiring a highly uniform gas mixture and of introducing additional absorption due to pressure broadening. This pressure broadening is more serious for two-photon resonant processes since broadening of the two-photon resonance reduces the nonlinear susceptibility [2].

ReportDOI
01 Sep 1977
TL;DR: In this article, a single-molecule detection using a pulsed ultraviolet laser was shown to be possible by using a simple geometry accounting for diffusion and reaction in the central portion of the laser beam.
Abstract: Cesium iodide in the presence of a buffer gas was dissociated with a pulsed ultraviolet laser, which will be referred to as the source laser. This created a population of atoms at a well defined time and in a compact, well defined volume. A second pulsed laser, with a beam that completely surrounded that of the first, photoionized the cesium after a known time delay. This laser will be referred to as the detector laser. It was determined that for short time delays, all of the cesium atoms were easily ionized. When focused, the source laser generated an extremely intense fluence. By accounting for the beam intensity profile it was shown that all of the molecules in the central portion of the beam can be dissociated and detected. Besides proving the feasibility of single-molecule detection, this enabled a determination of the absolute photodissociation cross section as a function of wavelength. Initial studies of the time decay of the cesium signal at low argon pressures indicated a non-exponential decay. This was consistent with a diffusion mechanism transporting cesium atoms out of the laser beam. Therefore, it was desired to conduct further experiments using a tightly focused source beam, passing along themore » axis of the detector beam. The theoretical behavior of this simple geometry accounting for diffusion and reaction is easily calculated. A diffusion coefficient can then be extracted by data fitting. If reactive decay is due to impurities constituting a fixed percentage of the buffer gas, then two-body reaction rates will scale linearly with pressure and three-body reaction rates will scale quadratically. Also, the diffusion coefficient will scale inversely with pressure. At low pressures it is conceivable that decay due to diffusion would be sufficiently rapid that all other processes can be neglected. Extraction of a diffusion coefficient would then be quite direct. Finally, study of the reaction of cesium and oxygen was undertaken.« less

Patent
03 Nov 1977
TL;DR: In this paper, low temperature selective infrared excitation of 85 krypton difluoride in an isotopic compound mixture is used, as well as cryogenic matrix isolation and inert buffer gas isolation techniques.
Abstract: Methods and apparatus for separating krypton isotopes utilizing low temperature selective infrared excitation of 85 krypton difluoride in an isotopic compound mixture. Multiphoton IR excitation and UV excitation techniques are used, as well as cryogenic matrix isolation and inert buffer gas isolation techniques.