Bojan B. Radak

Efficient small-scale TEA CO2 laser for material surface modification

An efficient small scale TEA (Transversely Excited Atmospheric) CO2 laser has been considered. The laser was a low flowing, UV preionized, pulsed system. Specific design of the head as well as the electrical circuit ensure the laser operation with high efficiency and reliability. Nonconventional CO2/Y, Y equals N2/H2; H2/He and H2 gas mixtures showed relatively high energy output. CO2/N2/H2 mixture as the most superior one produces output energy and peak power of 220 mJ and 1.40 MW, respectively. High-energy output of the laser was employed for surface modification of austenitic stainless steel AISI 316 and titanium nitride (TiN) coating deposited on the same steel substrate. Used laser peak power densities of 100 and 170 MW/cm2 have induced the morphology changes of AISI 316 steel and TiN coating, respectively.

Pressure effects on CO2-laser coincidences with ethene and ammonia investigated by photoacoustic detection

Abstract Carbon dioxide laser coincidences were investigated by photoacoustic detection at laser lines 10P(28) and 9P(28) with ethene and at 10P(20) and 10P(16) with ammonia. The intensities of coincidences were measured as a function of pressure of a buffer gas (dry air) and pure gas. The intensities of two ammonia coincidences show an inversion with pressure. A method of eliminating all pressure effects other than those of spectral nature from the PA signal was introduced. This enabled deriving the pressure broadening coefficients of the coinciding absorption lines.

CO2-laser photoacoustic spectroscopy of deuterated and tritiated forms of hydrogen sulphide

Abstract Spectra of coincidence of HDS and D2S IR absorption with CO2-laser emission lines were recorded by use of photoacoustic detection in the entire range of CO2-laser emission. The strongest absorption of the laser radiation was found at 970.55 cm−1 [laser line R(12)] for HDS and at 974.62 cm−1 [laser line R(18)] for D2S. The exceptional sensitivity of the method was also used for obtaining photoacoustic data on HTS absorption in the CO2-laser emission range with the lowest feasible concentration of 250 ppm HTS in H2S. In this case, the strongest absorptions were found at 1045.02 cm−1 [laser line P(22)] and at 971.93cm−1 [laser line R(14)].

Two band line interference in CO2 as a function of temperature studied by laser photoacoustic spectroscopy

The absorption spectrum of carbon dioxide in the 9–11 μm region was studied as a function of temperature theoretically and by photoacoustic (PA) spectroscopy with a CO 2 laser as the radiation source.

IR Laser-Induced Changes to L-adrenaline-D-hydrogentartrate Incorporated in KBr Matrices

Changes in the pharmaceutical L-adrenaline-D-hydrogentartrate, incorporated in KBr matrices, induced by a pulsed carbon-dioxide Transversely Excited Atmospheric (TEA) laser, were observed. Modifications of the sample were monitored via infrared spectra. Special attention was devoted to the dependence of the sample changes on the laser energy density used. The irradiation of the pharmaceutical has been performed with two laser lines at wavelengths of about 10.6 µm. The laser lines coincide well with the absorption band of the pharmaceutical, which is assigned to the ring vibrations/out-of-plane OH deformation vibrations, within the carboxyl (COOH) group of L-adrenaline-D-hydrogentartrate. Laser energy densities of 1.20 and 1.70 J/cm2 modified the pharmaceutical/compound. It was found that this modification is in essence a thermal effect. The level of change showed a dependence on the laser energy density, number of accumulated laser pulses and temporal shape of the pulse.

Two band line interference in CO2as a function of temperature studied by laser photoacoustic spectroscopy

The absorption spectrum of carbon dioxide in the 9–11 μm region was studied as a function of temperature theoretically and by photoacoustic (PA) spectroscopy with a CO 2 laser as the radiation source.

Determining pressure broadening coefficients by photoacoustic detection with a non-tunable laser

A procedure for determining the pressure broadening coefficients of spectral gas absorption lines is introduced. An important part of this procedure is the experimental determination of the photoacoustic signal dependence on pressure and its elimination from the purely spectral factors related directly to pressure broadening.

Two band line interference in

The absorption spectrum of carbon dioxide in the 9–11 μm region was studied as a function of temperature theoretically and by photoacoustic (PA) spectroscopy with a CO 2 laser as the radiation source.

CH3F absorption of the CO2-laser emission measured by the photoacoustic technique

Spectra of coincidence of SO2 IR absorption with CO2-laser emission at pressure of 50,100 and 450 Torr were recorded by the use of a photoacoustic detection method in the whole range of CO2-laser emission. The spectra show that SO2 absorbs many CO2-laser lines in the range 1084–1071 cm−1 with the strongest absorption at 1082.29cm−1, laser line R(26). The intensities of all absorptions rise with increasing pressure, but some absorptions change their relative intensity with respect to one another. In addition, the fine structure of line spectra, characteristic of lower pressure samples, disappear as pressure is increased.

Buffer gas effect on laser photoacoustic spectra of methyl chloride

Spectra of coincidence of CH3C1 IR absorption with CO2-laser emission were recorded by a photoacoustic detection method in the whole range of CO2-laser emission. The samples were neat gas and mixtures with argon, at several pressures (10 to 600Torr) so that pressure effects could be observed. The results show that argon affects absorption of CO2-laser emission quite differently from neat chloromethane, both regarding the most prominent coincidences and background absorption.