ABSTRACT
Coherent radiation at various VUV wavelengths, e.g., 125.9, 126.1, and 125.4 nm, has been generated through fourwave mixing processes enhanced by two-photon resonances in xenon. Maximum efficiencies of the order of 10(-4) were achieved. Maximum output intensities of difference generation (2omega(1) - omega(2)) for 7p[0 (1/2)](0), 7p[1 (1/2)](2), and 6p' [1 (1/2)](2) resonant states occurred at xenon pressures of 24, 12.5, and 4 Torr, corresponding to values of phase mismatch per atom of 1.2 x 10(-18), 2.3 x 10(-18), and 7.1 x 10(-18) esu, respectively. Parametric generation at 117.0 nm through the 7s[1(1/2)](0)(1) state was also observed.
ABSTRACT
Measurements on the stability of a coaxial flashlamp-pumped dye laser demonstrated that the quality of the output can be dramatically improved by isolating the dye cell thermally from the flashlamp and ensuring uniform axially symmetric flow of the dye throughout the cell. A quadraxial laser tube in which the dye cell is surrounded by an evacuated annulus to provide thermal isolation and is terminated by specially designed end caps to provide uniform injection and removal of the dye solution was tested in a standard cavity with a 1200-line/mm grating in Littrow configuration as the dispersive element. The performance characteristics were 1-mrad divergence, 0.5-A bandwidth of the spectral distribution, and 0.04-A jitter of wavelength at maximum intensity.
ABSTRACT
It has been shown that a dense (>10(14) -cm(-3)) atomic vapor, irradiated by a saturating pulse of resonance radiation, will ionize on a time scale of <10(-6) sec. The ionization can be 95% complete and has been observed in Li, Na, Ca, Sr, and Ba. A large number of physical processes contribute to the ionization with different processes dominating at different stages in the ionization. These processes are discussed, and two models for calculating the ionization are described. The results of the various experiments and the applications to the spectroscopy of ions and to atomic physics studies in general are reviewed.
ABSTRACT
A recently developed laser-excitation technique has been used in the first photoabsorption studies of the even-parity 2p(5)3s3p and 2p(5)3s4p autoionizing levels of Na I. The observed-level values are compared, where applicable, with those previously obtained by ejected-electron spectroscopy of collisionally excited Na, and the identifications are confirmed by ab initio calculations.
ABSTRACT
Radiation was generated between 1210 and 1230 A by four-wave sum mixing in beryllium vapor where the 2s(2)(1)S-2s3d(1)D transition was two-photon resonant. Results indicate that beryllium will be an efficient nonlinear medium in this spectral region with improvements to the stability of the furnace to allow phase matching and operation at higher pressures.
ABSTRACT
Experiments with optical radiation often require separation of a region of relatively high pressure from a lower-pressure region while allowing transmission of radiation between regions. When work is done with vacuum ultraviolet radiation (VUV), the problem is made more difficult by the small number of transparent materials, there being no bulk materials which transmit at shorter wavelengths than the 1050-A cutoff of LiF. In this paper we report the successful use of glass capillary arrays combined with differential pumping to sustain large pressure differences with excellent transmission of radiation throughout the VUV region.
ABSTRACT
A ground-based differential absorption lidar (DIAL) system is described which has been developed for vertical range-resolved measurements of water vapor. The laser transmitter consists of a ruby-pumped dye laser, which is operated on a water vapor absorption line at 724.372 nm. Part of the ruby laser output is transmitted simultaneously with the dye laser output to determine atmospheric scattering and attenuation characteristics. The dye and ruby laser backscattered light is collected by a 0.5-m diam telescope, optically separated in the receiver package, and independently detected using photomultiplier tubes. Measurements of vertical water vapor concentration profiles using the DIAL system at night are discussed, and comparisons are made between the water vapor DIAL measurements and data obtained from locally launched rawinsondes. Agreement between these measurements was found to be within the uncertainty of the rawinsonde data to an altitude of 3 km. Theoretical simulations of this measurement were found to give reasonably accurate predictions of the random error of the DIAL measurements. Confidence in these calculations will permit the design of aircraft and Shuttle DIAL systems and experiments using simulation results as the basis for defining lidar system performance requirements.
