E. C. C. Vasconcellos

Far infrared laser lines produced by methanol and its isotopic species: A review

Methanol (CH3OH) is considered today one of the most important active media for the generation of laser radiation in the far-infrared (FIR) spectral region. Together with ten of its other isotopic species, it is responsible for the major part of the laser lines generated by the optical pumping technique. Due to the extreme importance of those molecules as laser generators, we understood that there was a necessity of a comprehensive work which would include as much pratical information as possible about each line.Chang et al(1) early recognized methanol as a source of strong FIR laser lines. Since then, more than 100 papers were published containing information about new laser emission. Recently, Moruzzi et al(114) presented a review of 575 lines produced by12CH3OH. In the present paper, we have extended the review to the various isotopic modifications of this molecule (namely13CH3OH, CD3OH,13CD3OH, CD3OD,13CD3OD, CH3OD, CH318OH, CH2DOH, CH2DOD and CHD2OH), a total of nearly 2000 lines with wavelengths ranging from 19µm to 3030µm.

Methanol and the optically pumped far-infrared laser

New results on the generation and spectroscopic analysis of optically pumped far-infrared (FIR) laser emission from CH/sub 3/OH have been obtained as part of a systematic study of methanol isotopomers as FIR laser sources utilizing the extended line coverage available from a recently developed high-resolution CO/sub 2/ laser of high efficiency. For normal CH/sub 3/OH, six new short-wavelength lines have been found using a 2 m long Fabry-Perot FIR laser cavity. Accurate heterodyne frequency measurements are reported for 14 CH/sub 3/OH FIR laser lines, nearly all above 100 cm/sup -1/, as well as accurate frequency offsets for most of the corresponding CO/sub 2/ pump lines. Spectroscopic assignments are presented for nine high-frequency FIR laser lines in four pump systems.

Effect of low intensity helium-neon (HeNe) laser irradiation on experimental paracoccidioidomycotic wound healing dynamics.

The effect of HeNe laser on the extracellular matrix deposition, chemokine expression and angiogenesis in experimental paracoccidioidomycotic lesions was investigated. At days 7, 8 and 9 postinfection the wound of each animal was treated with a 632.8 nm HeNe laser at a dose of 3 J cm−2. At day 10 postinfection, the wounds were examined by using histologic and immunohistochemical methods. Results revealed that laser‐treated lesions were lesser extensive than untreated ones, and composed mainly by macrophages and lymphocytes. High IL‐1β expression was shown in the untreated group whereas in laser‐treated animals the expression was scarce. On the other hand, the expression of CXCL‐10 was found to be reduced in untreated animals and quite intensive and well distributed in the laser‐treated ones. Also, untreated lesions presented vascular endothelial growth factor (VEGF) in a small area near the center of the lesion and high immunoreactivity for hypoxia‐inducible factor‐1 (HIF‐1), whereas laser‐treated lesions expressed VEGF surrounding blood vessels and little immunoreactivity for HIF‐1. Laser‐treated lesions presented much more reticular fibers and collagen deposition when compared with the untreated lesion. Our results show that laser was efficient in minimizing the local effects observed in paracoccidioidomycosis and can be an efficient tool in the treatment of this infection, accelerating the healing process.

New FIR laser lines from CHD2OH optically pumped by a cw CO2 laser

This work reports 83 new optically pumped far infrared laser lines, using deuterated methyl alcohol, CHD2OH, as active medium. For each line we list the measured wavelength, its polarization relative to the pump line, the optimum gas pressure and the CO2 laser pump power at the maximum absorption.

Hydrazine—an excellent optically pumped far-infrared lasing gas: review

We summarize the 194 far-infrared lasing lines of hydrazine: 7 new lines, 144 lines that we reported recently, and 43 lines reported by other authors. Fewer than 5% of the 43 previously reported lines had wavelengths shorter than 200 μm, but 82% of our 134 lines (127 and 7 new), discovered in cw 12C16O2-laser-pumped hydrazine, were shorter than 200 μm; the shortest was at 49.2 μm. Of the 194 lines now known in hydrazine, 150 have been frequency measured. We present the pump line, the pump offset from the CO2 line center, the far-infrared wavelength and frequency, the optimum pressure, the relative intensity, and the relative polarization of each line.

New short-wavelength laser emissions from optically pumped /sup 13/CD/sub 3/OD

We report the discovery of 15 new laser emissions from /sup 13/CD/sub 3/OD when optically pumped with a CW CO/sub 2/ laser. The wavelengths of these lines, ranging from 57.5 to 135.2 /spl mu/m, are reported along with their polarization relative to the CO/sub 2/ pump laser, operating pressure and relative intensity. A three-laser heterodyne system was then used to measure the frequencies of 12 optically pumped laser emissions from this methanol isotope. These emissions range from 65.7 to 151.8 /spl mu/m and are reported with fractional uncertainties up to 2/spl middot/10/sup -7/.

Optically pumped13CH2F2 laser: Wavelength and frequency measurements

Laser action in carbon-13 difluormethane, C-13H/sub 2/F/sub 2/ was obtained by pumping with CO/sub 2/ CW laser lines from 10R4 to 9R44. Sixty-five lines ranging from 106 to 1220 microns were found. Wavelength, polarization and intensity measurements were performed. The frequencies of 57 of these lines were measured by the synthesis of two frequency-stabilized CO/sub 2/ lasers in a MIM diode. Most of these lines have intensities comparable to those of the well known C-12H/sub 2/F/sub 2/. 5 references.

Optically-Pumped Far-Infrared Laser Lines of Methanol Isotopomers: 12CH3OH, 12CH3OD, and 12CH2DOH

Twenty-seven new far-infrared laser lines from the isotopomers of methanol: 12CD3OH, 12CH3OD, and 12CH2DOH, were obtained by optically-pumping the molecules with an efficient cw CO2 laser. The CO2 laser provided pumping from regular, sequence, and hot-band CO2 laser transitions. The 2-m long far-infrared cavity was a metal-dielectric waveguide closed by two, flat end mirrors. Several short-wavelength (below 100 μm) lines were observed. The frequencies of 28 laser lines observed in this cavity (including new lines and already known lines) were measured with a fractional uncertainty limited by the fractional resetability of the far-infrared laser cavity, of 2 parts in 107.

New N/sub 2/H/sub 4/ far infrared laser lines and frequencies

Measurements have been made for 32 far infrared laser frequencies of optically pumped hydrazine, 30 of which are new. The wavelengths range from 95 to 528 /spl mu/m. A pair of frequency-stabilized CO/sub 2/ lasers were used as standards for the heterodyne frequency measurements. One of the lines can be used as a local oscillator for astronomical searches for /sup 14/N/sup +/, and other lines can be used to study transitions in metastable Ca. >

Laser Lines and Frequency Measurements of Fully Deuterated Isotopomers of Methanol

Fully deuterated isotopomers of methanol (12CD3OD and 13CD3OD) were optically pumped with a CO2 laser. Five new far-infrared laser lines were discovered in 12CD3OD and 25 in 13CD3OD in the range 43.697 to 719.426 μm. The frequencies of these new and some previously reported laser lines, the pump offset, the relative polarization, the relative intensity, and the optimum pressure of operation were measured.