S. C. Zerbetto

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.

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.

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.

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.

12CH2F2 and13CH2F2far-infrared lasers: New lines and frequency measurements

We report here the discovery of 13 new far-infrared laser lines from12CH2F2 and seven new lines from13CH2F2. Most of the new lines were pumped by high-J lines of the 9R branch of a cw-CO2 laser. Wavelengths range from 97.6 to 616.18 µm. Frequency, pump offset, relative polarization, and relative intensity were measured for most of the new lines.

Methanol isotopomers and the optically pumped far-infrared laser

Methanol and its isotopic species have been systematically investigated as sources of far- infrared (FIR) laser emission utilizing a newly designed optically pumped FIR laser system. The system combines several different FIR laser cavity designs with the extended line coverage available from a recently developed high-resolution CO2 laser of high efficiency. New FIR laser lines have been observed pumped by fundamental band CO2 lines of high J, sequence band lines, and hot-band CO2 transitions. The new FIR laser lines extend over a broad spectral region, and contribute significantly to the frequency coverage of the optically pumped FIR laser. Many new short-wavelength lines have been observed for normal CH3OH using a 2-m-long Fabry-Perot FIR laser cavity. Accurate heterodyne measurements have been made of the FIR laser frequencies and the CO2 laser pump offsets for many of the new lines.

New Far-Infrared Laser Lines and Frequency Measurements of Acetaldehyde and Vinyl Fluoride

Eight far-infrared laser lines have been obtained by optically pumping acetaldehyde (CH3CHO) and nine by pumping vinyl fluoride (CH2CHF) with a cw CO2 laser. The far-infrared laser structure used a metal-dielectric waveguide cavity. This is the first reported observation of four of the laser lines in acetaldehyde. In this work, we measure the frequency, optimum pressure of operation, relative intensity, relative polarization, and pump offset from CO2 laser-line center.

13CH3OH far-infrared laser: newly discovered lines, predictions, and assignments

We report 24 new laser lines from 13CH3OH methanol when pumped by a cw-CO2 laser. The majority of the lines are pumped by the 10R and 10SR bands of the CO2 laser. Two are pumped by the 9HP hot-band CO2 line. We measured 21 laser frequencies in this molecule; 18 from new lines and three from previously reported lines. We also remeasured and corrected the frequency of the 9P(44) pumped line as 3 378 404.87 MHz. Assignment of two lines: 10SR(17) - 77.5758 cm-1 and 10R(50) - 119.3020 cm-1, and predictions for other potential FIR laser lines with these two pumps are also included in this work.

Hydrazine: a very efficient laser in the far-infrared: a review

Until recently hydrazine had 35 known far-IR laser lines when optically pumped by a 12C16O2 cw-laser. We have discovered 127 new lines pumped by regular, sequence, and hot band lines of a 12C16O2 cw-laser. One hundred and one of these new lines have wavelengths less than 200 micrometers , the shortest wavelength line is 49.2 micrometers . Of the 162 known lines, 139 have been frequency measured. We list the pump line, pump offset, FIR wavelength and frequency, optimum pressure, relative intensity, and relative polarization for each line. Preliminary work has also identified 12 new lines when hydrazine is pumped by an N2O laser.

Difluoromethane far-infrared lasers: new laser lines and frequency measurements

Difluoromethane (12CH2F2) together with its 13C isotopomer is a well known efficient laser medium for the generation of far-infrared laser lines. Both isotopers have produced nearly 200 laser lines with wavelengths in the range between 95.6 and 1448.1 micrometers . We report here the discovery of 13 new far-IR laser lines from 12CH2F2 and seven new lines from 13CH2F2. MOst of the new lines were pumped by high J-lines of the 9R branch of a cw-CO2 laser. Wavelengths range from 97.6 to 616.18 micrometers . Frequency, pump offset, relative polarization, and relative intensity were measured for most of the new lines.