New CW FIR laser action by Stark tuning from optically pumped CH3OH and CH3OD

Fifteen new CW FIR laser lines are reported from Stark tuned CO2optically pumped CH3OH and CH3OD. Four new CW laser lines have also been observed from zero field optically pumped CH3OD, three with a CO2laser, and one with an N2O laser.     

Assignments of the high power optically pumped CW laser lines of CH3OH

Thirteen far IR laser lines in CH3OH, optically pumped by a CO2laser, have been assigned toa- andb-type transitions in ν5CO-stretch band. Identification procedures used were: a frequency match between the CO2pump and CH3OH absorption, frequency match of laser lines and CH3OH ν5transitions, polarization of far IR radiation, cascade and competition effects between far IR laser lines, and frequency consistencies. An improved set of molecular constants for ν5transitions were also obtained.     

New optically pumped CW submillimeter emission lines from OCS CH3OH and CH3OD

A new emission line has been observed by optically pumping OCS with 9 μm R(8) CO2laser radiation and has been tentatively assigned. In addition, fourteen new emission lines of CH3OD and four of CH3OH have been discovered.     

Assignment of laser lines in optically pumped CH3OH

A number of far-infrared laser emission lines from CH3OH, pumped by a CO2laser, have been assigned to specific energy levels of the rotation-internal rotation spectrum in the first excited CO stretch state. The assignments are based on comparison with the established model for the vibrational ground state, and on criteria concerning internal consistency, polarization, and line strength.     

Submillimeter laser action of CW optically pumped CF3Br

Far infrared laser action at 823 and 883 μm is reported for the first time from the optically pumped CF3Br molecule. This molecule exhibits strong absorptions in thePandRbranches of the 9 μm band of the CW CO2laser. Tentative assignments are proposed for the first two transitions observed.     

Collisional narrowing in the optically pumped CH3OH and CH3F lasers

The gain linewidth of the optically pumped CH3F laser is observed to narrow and rebroaden with the addition of He. In addition, we observe the same effect in the CH3OH laser with the addition of the polyatomic buffer gases SF6and CS2. These results offer conclusive evidence of the Dicke narrowing phenomena in these inverted pure rotational transitions. The effect is observed using a high harmonic mixing technique in a Schottky barrier diode.     

New FIR laser lines from optically pumped CH3OH: Measurements and assignments

26 new FIR laser lines have been observed in CO2laser pumped CH3OH, and together with some previously observed lines their wavelengths have been measured with a relative accuracy of3 times 10^{-4}by using the FIR resonator as a scanning Fabry-Perot interferometer. Based on the internal consistency of the data, it is suggested that a number of the lines originate from combination bands involving simultaneous excitation of the CO stretch mode and a different vibrational mode.     

On the assignment of weak FIR laser lines in optically pumped CH3OH

The rotational-torsional-vibrational quantum numbers of the methanol states involved in the FIR laser action for 9P(22) and 9P(32) CO2pumping are derived. The pumping of weak FIR lines occurs through hot-band and weakly allowed IR lines.     

New CW far-infrared laser lines from CO2laser-pumped CD3OH

Twenty-one new CW far-infrared laser lines have been observed from the CD3OH molecule pumped by a CO2laser. The wavelengths of these new lines fall in the short wavelength range from 34.5 to 287 μm.     

New efficient CW far-infrared optically pumped CH2F2laser

Far-infrared laser action is reported for the first time from the optically pumped CH2F2molecule. Lasing on twelve FIR transitions was produced by pumping with six emission lines in theRbranch of the 9.6 μm band of the CW CO2laser. High conversion efficiencies of up to 20 percent of the quantum limit have been obtained with the stronger FIR laser lines.     

Submillimeter laser action of CW optically pumped CF2Cl2 (Fluorocarbon 12)

Eleven new CW far infrared (FIR) laser lines have been observed in the 600 μm–1200 μm range from the CF₂Cl₂ (Fluorocarbon 12) molecule optically pumped by a CO₂ laser. A 510^?4–10^?3 accuracy is achieved in the measurement of the FIR wavelengths. The frequency offset between the CO₂ pump center and the absorption line centers are measured using the transferred Lamb dip technique. Owing to a recent spectroscopic study of the CF₂ ³⁵Cl₂ molecule three lines may be assigned with great confidence as rotational transitions in thev ₆ vibrational band 923 cm^?1 of this main isotope.     

Analysis of CH3OH far infrared laser lines optically pumped by sequence band and isotopic CO2lasers

Assignments are presented for seven far infrared (FIR) laser lines of CH3OH pumped by theS-9P(31),18-10R(24),13-9R(26), and13-9P(16)CO2laser lines, plus an interesting speculation for the FIR line pumped by the18-9P(12)CO2line. Frequencies have been deduced to a substantially improved accuracy of ±0.001 cm^-1from IR and FIR spectroscopic combination differences for most of the assigned lines as well as three other predicted transitions. In addition, accurate frequencies are given for 13 predicted FIR laser transitions which are expected from the IR spectrum to be pumped by three¹⁶O¹²C¹⁸O laser lines.     

Observation and assignment of large offset farinfrared laser lines in CH3OH optically pumped by a CO2waveguide laser

Four new FIR laser lines at 62.98, 48.77, 224.53, and 190.65 μm are reported from CH3OH, optically pumped by the 10R34 and 9R10 lines of a waveguide CO2laser. Measurements performed by several techniques confirm that the pump offsets are outside the tuning range of conventional CO2lasers. Two of the lines are assigned as highJtransitions within the torsional ground state of the CO stretch.     

FIR laser lines of CH3OH pumped by CO2laser sequence lines

We report on the utilization of a sequence band CO2laser as the pumping source for new FIR laser lines of CH3OH.     

Far infrared laser lines in CH3OH, optically pumped to CO stretch states and to strongly interacting vibrational states

A commented table is presented, containing 90 assigned FIR emission lines of the CH3OH laser, which can be dixectly or indirectly related to the torsional ground state of the CO stretch. Based on a model, which empirically takes into account interactions with other vibrational modes, the table compares measured and calculated pump and emission frequencies. For 14 pump transitions withJ leq 26, the rms deviation is 0.005 cm^-1. For 26 FIR emission transitions involvingJ leq 26, where the accuracy of the model can be checked against frequency measurements, the rms deviation is 0.004 cm^-1. Pump transitions to a strongly perturbing mode are identified, and accurate energy level parameters for this mode are given.     

New laser lines with wavelengths from λ = 61.7 µm down to λ = 27.7 µm in optically pumped CH3OH and CD3OH

25 new CW far infrared laser lines have been observed with wavelengths fromlambda = 61.7 mum down tolambda = 27.7 mum. We have significantly increased the number of known short wavelength laser lines and extended the laser line spectrum to the 30 μm region by using a BaF2outcoupling system.     

Broad-band gain in optically pumped S2

TheB^{3} Sigma-_{u} rightarrow X^{3}Sigma-_{g}system of S2has many of the characteristics required of a tunable laser: a broad fluorescence spectrum and a Franck-Condon shift between theBandXstates. In this paper, theupsilon' = 4level of theB^{3} Sigma-_{u} rightarrow X^{3}Sigma-_{g}system of S2is pumped by the absorption of the 308 nm XeCl excimer radiation. Rare gas-S2collisions redistribute the population among theupsilon'levels, and the subsequent emission contains intense bands throughout much of the neat UV and visible region of the spectrum. Broad-band gain is reported on two blue-green bands (2,17) and (3,18) populated by rare gas relaxation. Absorption is reported on the near UV bandsupsilon' = 0 rightarrow upsilon" rightarrow 6,7,8where the lower levels are filled by the transient population cascading down theXstate manifold. A fluorescence study is presented which examines the potential advantages and limitations of this system.     

Very short far-infrared pulses from optically pumped CH3OH/D, CH3F, and HCOOH lasers using an EQ-switched CO2laser as a pump source

Very short far-infrared (FIR) pulses were generated from optically pumped CH3F, CH3OH/D, and HCOOH lasers using aQ- switched, current pulsed (200 mA, 100 μs), low pressure (20 torr) CO2laser as a pump source. Values of 20 ns for the rise time and 50 ns for the decay time of the FIR pulses have been observed. The dependence of the FIR pulse shape parameters, i.e., rise time, decay time, and pulse buildup time, on the width of the pump pulse and the pressure of the molecular gas have been investigated experimentally. Due to the regular pulse shape, high repetition rate (350 Hz), high peak power (≳1 W), and broad spectral range (lambda = 100-500 mum), the pulses are very useful for purposes of solid-state and molecular time resolved spectroscopy.     

Optically pumped FIR laser action in chlorofluoromethane (CH2CIF)

Thirteen new submillimeter laser lines have been detected in chlorofluoromethane optically pumped with a CW¹²C¹⁶O2laser. Their wavelengths measured in a Fabry-Perot resonator to an accuracy better than 0.5 percent, lie between 175 and 1014 μm.