Optically pumped submillimeter laser lines from CH2F2 and CD2Cl2 using a12C18O2 CW laser

Thirty-nine new submillimetre laser lines in CH₂F₂ and twelve in CD₂Cl₂ have been obtained in a Fabry-Perot FIR resonator by optically pumping with a CW¹²C¹⁸O₂ laser. The wavelength range obtained for CH₂F₂ is 126m to 1091m and for CD₂Cl₂ 212m to 774m. The wavelength measurements are accurate to within 5.10^–3. The relative polarisations of the pump laser and the FIR laser output were also determined. Tentative assignments of the IR and FIR transitions were made using existing microwave data.     

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.     

13CH3OH and13CD3OH optically pumped fir laser: New large offset emission and optoacoustic spectroscopy

27 new, large offset, FIR laser lines from¹³CH₃OH and one from¹³CD₃OH have been discovered by pumping with a high tunability waveguide CW CO₂ laser. Optoacoustic measurements of isotopic methyl alcohol have also been performed and the pump offsets of the new and of previously known lines have been measured and checked. Frequency tunability by Stark effect has been observed for 6 strong lines. Some assignments are discussed.     

Frequencies of cw FIR laser lines from optically pumped CH2F2

The frequencies of 48 optically pumped cw FIR CH₂F₂ laser lines have been measured relative to stabilized CO₂ lasers. Uncertainties are estimated to be about 5 parts in 10⁷.     

Acoustooptic extension of the frequency tunability of CW CO2 lasers: New FIR lasers emissions from CH3OH and13CH3OH

We have increased the frequency tunability of our CW waveguide CO₂ lasers by means of an acoustooptic amplitude modulator, operating at the fixed frequency of 90 MHz. The up-shifted, or down-shifted, laser optical sideband can be generated independently by adjusting the orientation of the modulator. The efficiency is larger than 50%. The frequency tunability of the CO₂ laser around each laser line is thus increased by 180 MHz. To demonstrate the possibilities of this method, a source composed of the above modulator and of a CW, 300 MHz tunable waveguide CO₂ laser has been used for the search of new large offset FIR laser lines from optically pumped CH₃OH and¹³CH₃OH molecules. As a result 15 and 10 new large offset laser lines were discovered respectively. New assignments of some laser lines are also proposed. We have also measured the Stark effect, the offset, and the polarization of other already known lines. In particular a Stark effect frequency tuning of about 1 GHz is demonstrated for a laser line at 208.399 m.     

New FIR laser lines from optically pumped C2H3F, C2H3Cl, C2H3Br, C2H3CN, C2H5F, CH2CF2, HCOOH and CH3Br

Twenty-seven new cw far infrared laser lines with wavelengths between 137 and 988m have been observed from optically pumping C₂H₃F, C₂H₃Cl, C₂H₃Br, C₂H₅F, C₂H₃CN, CH₂CF₂, HCOOH and CH₃Br with a CO₂ laser. The wavelengths of these FIR laser lines were determined together with their optimum pressures and relative intensities.     

Far infrared laser frequencies of CH3OD and N2H4

The frequencies of 26 laser lines with wavelengths between 57 and 534 m have been measured in the optically pumped laser gases CH₃OD and N₂H₄. A pair of stabilized cw 12_{CO 2} lasers was used as a frequency standard for the heterodyne frequency measurements. Seven of the 26 lines are new.     

Optically pumped submillimeter laser lines from CD2Cl2 using a large tunability CW CO2 laser

Twenty-five new laser lines have been obtained in the wavelength region from 155 to 830 μm by optically pumping the CD₂Cl₂ (deuterated dichloromethane) molecule with a CW CO₂ laser having a tunability range of 300 MHz. The wavelength, polarization relative to that of CO₂ pumping radiation, and offset relative to the CO₂ center frequency were determined for all of the new lines and some other already known laser emissions. For all of them we give also the relative intensity and the optimum pressure of operation. Permanent address: Depto de Física e Química da FEIS — UNESP 15.378-000 Ilha Solteira-SP, Brazil     

Frequency measurements of CF2CHF and SO2 laser lines and a new far infrared laser line of HDCO

The emission frequencies of several optically pumped far infrared laser lines of CH₂CHF, SO₂ and HDCO molecules have been measured by mixing them with a harmonic of a millimeter-wave synthesizer operating in the range 78–118 GHz. A new line of HDCO at 1886 GHz has been found.     

Far infrared stimulated emissions from CO2 laser excited dichloromethane

Six new far-infrared laser frequencies have been obtained in CO₂-laser excited dichloromethane. Competing transitions have enabled assignments to be made to the v₇ band.     

Optically pumped CW fir laser: New submillimeter laser emissions from CH2DOH, CH3I, CD3I, and trioxymethylene

We obtained twelve new far infrared laser transitions by optically pumping the CH₂DOH, CH₃I, CD₃I and Trioxymethylene molecules with a CW CO₂ laser having a tunability range of 280 MHz. We measured the wavelength, polarization, relative intensity and pump offset relative to the CO₂ center frequency for all the new lines.     

Assignments of optically pumped CH3OD laser lines

Fifteen laser lines from CH₃OD pumped by a CO₂ laser are assigned to specific rotational energy transitions. These assignments have been obtained from the approximation that, except for one constant, the molecular constants in the excited CO stretching state are same as those in the ground state.     

Frequency measurements on far-infrared emissions from12C16O2-pumped methyl chloride and from12C18O2-pumped difluoromethane

The frequencies of 42 far-infrared laser lines have been measured by mixing with high-order harmonics of microwave frequencies in a Josephson junction. A total of 5 emissions between 334 and 1887 m have been measured from¹²C¹⁶O₂-pumped methyl chloride (CH₃Cl) and 37 emissions between 116 and 1092 m in¹²C¹⁸O₂-pumped difluoromethane (CH₂F₂). Additional data is given on the laser emission characteristics.Division of Electrical Science, National Physical Laboratory     

Optothermal spectroscopy of CH3CN by a waveguide CO2 laser: Atlas of absorption lines

An investigation of the absorption of CH₃CN at 63 lines of a tunable waveguide CO₂ laser has been performed using the optothermal technique.     

Optoacoustic Laser Stark spectroscopy and FIR laser action on CH3Br using a waveguide CO2 laser

The optoacoustic spectrum of CH₃Br around 10 m band lines of a tunable cw waveguide CO₂ laser is investigated. Several new infrared absorptions are observed and most of the correspond ing molecular transitions are assigned. Far infra red laser action is reported by pumping with the same CO₂ laser: pump offsets are given using the Transferred Lambs dip (TLD) technique. A new FIR laser emission is obtained and assigned. An optoacoustic Laser Stark spectroscopy technique is used to investigate off resonance infrared tran sitions.     

CO2 laser assisted removal of UO2 and ThO2 particulates from metal surface

Pulsed laser assisted removal of uranium dioxide and thorium dioxide particulates from stainless steel surface have been studied using a TEA CO₂ laser. Decontamination efficiency is measured as a function of laser fluence and number of pulses. Threshold fluence for the removal of UO₂ particulates has been found to be lower than that required for the removal ThO₂ particulates. Usage of a ZnSe substrate, that is transparent to the laser wavelength used here, enabled us to decouple the cleaning effect arising out of absorption in the particulates from that in the substrate and has contributed towards understanding the mechanism responsible for cleaning. The experimental observations are also corroborated by simple theoretical calculations.     

Infrared-microwave double resonance as an aid in assignment of optically pumped submillimetre laser lines: CH2CF2, CH2F2, and CH3OH

Infrared-microwave double resonance has been used to confirm recent assignments of optically pumped submillimeter wave laser lines in CH₂CF₂ and CH₃OH, as well as a tentative assignment of a line in CF₂H₂. Intracavity double resonance signals have also been obtained in CF₂CH₂ using a circular copper waveguide laser.     

Submillimeter emission lines from CD2Cl2 optically pumped lasers

Fifty-five new submillimeter laser lines from optically pumped CD₂Cl₂, have been obtained in a FIR metallic waveguide resonator. Twenty-seven lines, ranging from 184 m to 1387 m, and twenty-eight lines, from 219 m to 888 m, have been observed when using CW CO₂ laser and CW N₂O laser optical pumping, respectively. The accuracy of wavelength measurements are of the order of 3.10^–3.     

Measurements and assignments of new large offset CD3OH FIR laser lines

By using an acoustooptic modulator we extend the 300 MHz tunability of a waveguide CO₂ laser to 480 MHz. The CD₃OH was optically pumped by the 10R(32), 10R(34), and 10R(36) CO₂ laser lines, and 17 new FIR laser lines were discovered. The Stark effect on previously known FIR laser lines was investigated, and some tentative FIR laser lines assignments are suggested.     

FIR Stark spectroscopy on optically pumped CH3OH laser

An extensive theoretical and experimental analysis of the absorption and emission spectrum of a CH₃OH FIR-laser excited by a conventional CO₂ laser is presented. Particular interest is devoted to the Stark shifts of the pump and lasing lines and to the electric field dependence of the Fir-laser output of the various lines. The offsets with respect to the exciting radiation and the Stark shifts of the IR absorption (pump) lines are measured by means of the transferred Lamb dip technique. The theoretical behaviours of the Stark patterns are calculated for several choices of the quantum numbers and selection rules involved in the transitions. A large variety of experimental results are reported and compared to theory. Non-linear Stark shifts have been observed for the 37.5m FIR laser line and for the IR-pump transitions excited by the 9-P(38) and 10-R(38) CO₂ laser Lines. Line assignments are proposed and new FIR laser lines are reported.