Cw Carbon Dioxide Research Articles

Effect of laser power on the structure and specific surface area of laser-induced graphene

Laser-induced graphene (LIG) is a highly porous carbon material with prospects for application in various fields of modern electronics, energy and medicine. In this work, LIG film samples with the size of 5 × 10 mm were synthesized on the surface of polyimide film using line-by-line scanning of focused radiation from a cw carbon dioxide laser. Studies using scanning electron microscopy and Raman spectroscopy revealed that the structure of the resulting material depends significantly on the laser power. Measurements of the specific surface area Ssa of the synthesized carbon material, carried out by the well-known BET method during adsorption and desorption of gaseous nitrogen, showed that Ssa significantly depends on the laser power. At a line scanning speed of 220 mm/s, 25 μm spacing between lines and a focused laser beam diameter of 120 μm, an increase in power from ~1.7 to 8.2 W leads to a decrease in Ssa from ~370 to ~100 m2/g. At the same time, the ratio of the total area of all LIG pores to the area of the obtained film varies in the range ~ 365–660 and reaches its maximum value of 660 at a power ~ 4.3 W.

A Study On The Effect of Using Various Reflectivities of Output Couplers on CW Carbon Dioxide Laser Performance

A Study On The Effect of Using Various Reflectivities of Output Couplers on CW Carbon Dioxide Laser Performance

Two stage laser stabilization using external cavities: Application to a 10 μm CO2 laser locked to an OsO4 transition

A cw carbon dioxide laser, operating on the 10 μm R(0) transition (28.832 THz), was stabilized by locking its frequency to an evacuated Fabry–Perot cavity. The Fabry–Perot cavity was in turn stabilized to the saturated absorption resonance of the Q(15) line of 188OsO4 , contained in a second Fabry–Perot cavity. Cesium-clock referenced, frequency chain measurements of the resultant line frequency are presented together with detailed studies of the line shift sensitivities to various operating parameters.

Discovery and measurement of optically pumped far-infrared laser emissions in 13CD3OH

We report the discovery of four laser emissions from the partially deuterated C-13 methanol isotope 13CD3OH when optically pumped with a cw carbon dioxide (CO2) laser. The wavelengths of these lines, ranging from 45.3 to 108.9 μm, are reported along with their polarizations relative to the CO2 pump laser, operating pressure, and relative intensity. A three-laser heterodyne system was then used to measure the frequencies of eight optically pumped laser emissions from this methanol isotope. These emissions range from 53.4 to 126.1 μm and are reported with fractional uncertainties up to ±2×10-7.

Absolute frequency measurement of a CO2/OsO4 stabilized laser at 28.8 THz

A cw carbon dioxide laser operating on the 10 μm R(0)I transition (28.832 THz) was frequency stabilized by a servo lock to the saturated absorption dip of the Q(15) transition of 188OsO4. The laser frequency was measured with a cesium-clock-based frequency chain. In addition, the absorption line frequencies Q(14) of 188OsO4 and sQ(4,3) of 15NH3, were measured relative to the frequency of Q(15).

Infrared predissociation spectrum of the H3+ ion. II

The infrared predissociation spectrum of the H3+ ion has attracted considerable attention; theoretical models have been developed which account for many of the observed features and which make further predictions. This paper describes the results of experiments designed to test these predictions. The spectrum is recorded by bringing a mass-selected H3+ ion beam into parallel or antiparallel coincidence with a cw carbon dioxide infrared laser beam. In the earlier work, 27 000 lines were observed over the range 874–1094 cm−1, each line being recorded by detecting H+ fragment ions produced by predissociation. The spectrum varied according to the H+ kinetic energy window selected, and it was proved that many of the lines arise from metastable states of H3+ lying above the H2+H+ dissociation limit. The spectrum showed no immediately recognizable pattern, but low resolution convolutions revealed the existence of a coarse-grained structure of four main peaks. The isotopic species H2D+ and D2H+ showed similarly complex spectra which, however, differed depending on whether H+ or D+ fragments were detected. The most important conclusion from subsequent theoretical models is that the metastable states involved are in a region of classical chaos and hence cannot be simply assigned in terms of vibrational modes. However, the coarse-grained spectrum is associated with the remnants of a periodic orbit in which quasilinear H3+ undergoes a large amplitude bending motion. Rotational angular momentum barriers lead to trapping of these essentially regular states, which are embedded in a classically chaotic manifold. Semiclassical trajectory studies and three-dimensional quantum mechanical calculations are consistent with each other. Our present experimental methods are described and questions concerning reproducibility are addressed. We describe new measurements over the range 964–992 cm−1 spanning the position of one of the peaks observed earlier in the convoluted spectrum. The H3+ spectrum is recorded for a series of different H+ kinetic energy windows and the results are summarized in bar charts. Convolutions of the data recorded for H+ ions with very small center-of-mass kinetic energies are consistent with the earlier results and with theoretical predictions, but also reveal additional structure. Convolutions for large H+ kinetic energies (≥500 cm−1) reveal less evidence of characteristic structure. Measurements over the region 1025–1045 cm−1 are also described; they are only for very small H+ kinetic energy release, but the linewidths are also tabulated. Most of the metastable states of H3+ predissociate predominantly through a single channel, but examples of multiple dissociation channels have also been recorded. Direct measurements of some predissociation lifetimes are presented. Selected regions of the spectra of D2H+ and H2D+, measured by recording H+ and D+ fragments separately with kinetic energy windows from 0 to 3000 cm−1, are described. The results are in excellent agreement with theoretical predictions, as also are measurements of the background spontaneous predissociation.

Development of microstructure in laser surface alloying of steel with chromium

Laser surface alloying (LSA) was used to formin situ Fe-Cr-C alloys on AISI 1018 steel substrates. Chromium powders of different particle sizes were mixed together to obtain optimum packing density of the powder deposited on the substrate. The surface was then melted using a 2kW CW carbon dioxide laser. The processing conditions were related to solute (chromium) content, microstructural refinement of the laser alloyed zone and the heat affected zone (HAZ). The microstructure of the laser surface alloyed region was investigated by optical, scanning and transmission electron microscopy, and X-ray microanalysis techniques. Microstructural study showed a high degree of grain refinement and an increase in solid solubility of alloying element. This process produced a fine distribution of complex type of carbide precipitate in the martensite-ferrite matrix because of the high cooling rate. An alloy of this composition does not show any retained phase. The nature of alloying and chemical diffusion profile as a function of intertrack separation distance affects the final content of alloying element in the surface layer.

Photochemistry and photophysics of small heterocyclic molecules. 2. CW carbon dioxide laser inducement of the bimolecular reaction of the thiirane

Photochemistry and photophysics of small heterocyclic molecules. 2. CW carbon dioxide laser inducement of the bimolecular reaction of the thiirane

Coherent Optical Radar

A coherent optical radar is described. The transmitter is a continuous wave (cw) carbon dioxide laser scanned over a 25 mrad x 25 mrad field of view. Radiation scattered by targets within the field is coherently detected by the system, allowing Doppler shifts to be measured. After processing, the detected signals are displayed on a monitor, with target velocity colour coded. Examples of the images obtained to date are given, along with typical detector output signals. The results of some preliminary work on frequency-modulated continuous wave techniques, which allow both target range and velocity to be extracted, are also given.

Laser-Induced Reactive Evaporation and Condensation

ABSTRACTA study of laser-induced reactive evaporation-condensation is presented. This considers coevaporation of metallic, and non-metallic species, by a cw carbon dioxide laser beam, within a reducing environment (98.5% hydrogen, 1.5% methane). A heated W filament placed in proximity of the laser beam-substrate interaction zone produces W for deposition via chemical vapor transport reactions. Composite thin films of a W matrix containing amorphous silica fibers have been deposited on nickel alloy substrates. These films form at rates of about 1 micron/sec, and are found to be adherent to the substrates. The diameter of the fibers is between 25 nm and 120 nm, depending on the interaction time. Various analytical techniques have been employed to characterize as-synthesized layers. Mechanisms of this process are discussed.

He–Ne and cw CO_2 laser long-path systems for gas detection

This paper describes the design and testing of a laboratory prototype dual He-Ne laser system for the detection of methane leaks from underground pipelines and solid-waste landfill sites using differential absorption of radiation backscattered from topographic targets. A laboratory-prototype dual cw carbon dioxide laser system also using topographic backscatter is discussed, and measurement results for methanol are given. With both systems, it was observed that the time-varying differential absorption signal was useful in indicating the presence of a gas coming from a nearby source. Limitations to measurement sensitivity, especially the role of speckle and atmospheric turbulence, are described. The speckle results for hard targets are contrasted with those from atmospheric aerosols. The Appendix gives appropriate laser lines and values of absorption coefficients for the hydrazine fuel gases.

ChemInform Abstract: SLOW OXIDATION OF N‐BUTANE INDUCED BY CW CARBON DIOXIDE LASER VIBRATIONAL PHOTOEXCITATION

Chemischer InformationsdienstVolume 15, Issue 21 Preparative Organic Chemistry ChemInform Abstract: SLOW OXIDATION OF N-BUTANE INDUCED BY CW CARBON DIOXIDE LASER VIBRATIONAL PHOTOEXCITATION C. LALO, C. LALOSearch for more papers by this authorF. LEMPEREUR, F. LEMPEREURSearch for more papers by this authorJ. MASANET, J. MASANETSearch for more papers by this authorJ. TARDIEU DE MALEISSYE, J. TARDIEU DE MALEISSYESearch for more papers by this author C. LALO, C. LALOSearch for more papers by this authorF. LEMPEREUR, F. LEMPEREURSearch for more papers by this authorJ. MASANET, J. MASANETSearch for more papers by this authorJ. TARDIEU DE MALEISSYE, J. TARDIEU DE MALEISSYESearch for more papers by this author First published: May 22, 1984 https://doi.org/10.1002/chin.198421131AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume15, Issue21May 22, 1984 RelatedInformation

Design of a low pressure CW carbon dioxide laser

The purpose of this paper is to describe the design and the construction of a continuous wave CO 2 laser for single line operation. This laser operates in a single axial mode with a frequency stabilization, at the maximum of the power profile, of better than 100 KHz. The output power is in the 0.1–5 W range. A variable coupling experiment is also described. This was used to obtain the gain of the amplifying medium and the optimum coupling for the maximum output power.

A boron nitride CW Carbon dioxide waveguide laser for optically pumping heavy water

Boron nitride has been used to fabricate a 1 cm 3 CW CO 2 capillary waveguide laser which operates at 130 torr gas pressure, and generates 7 W of 10 μm radiation untuned and up to 3 W on individual grating-selected emission lines. Pressure broadened gain profiles are limited to ±200 MHz from line centre by longitudinal cavity mode spacing. Increased absorption of the 9μm band R(22) line by D 2O vapour is observed as this line is tuned across the broadened gain profile towards its D 2O absorption.

Continuously operating CO2laser with a non-self-maintained discharge

A non-self-maintained gas discharge was used to excite the active medium of a cw carbon dioxide laser. Preionization was produced by an electron beam of 150 keV energy. The specific output power from a mode volume was 3 W/cm and the efficiency was 7%. A study was made of the influence of the processes occurring in the cathode region on the stability of the discharge and on the energy characteristics of the laser.

Ablative material response to CO2 laser radiation

Ablative materials performance in high radiative heat flux environments produced by CW carbon dioxide laser