The infrared spectra of NH4HS and ND4DS have been recorded from 200 to 4000 cm−1 at liquid nitrogen temperatures, and the Raman spectra of these substances have been recorded from 0 to 4000 cm−1 over the temperature range 83–390°K. No evidence of a second solid phase was obtained. Internal and external fundamentals were assigned, in detail, based on selection rules, isotopic frequency shifts, and analogy with other structurally similar salts. Barriers to anion and cation reorientation of 3.8 and 1.9 kcal/mole, respectively, have been calculated from librational assignments. The implications of the infrared spectrum of NH4HS for the possible spectroscopic detection of this substance in the atmosphere of the planet Jupiter are discussed.
Intense three wave mixing (3WM) spectra are reported for transient fragments produced by 266 nm laser photolysis of benzene and several substituted benzenes. Single pulse broadband 3WM spectra taken with an optical multichannel analyzer establish that the fragments are primary photoproducts obtained under collision-free condition. The spectra consist of many features at anti-Stokes frequency shifts of 900–3100 cm−1 from a 532 nm ω1 pump. 90° fluorescence studies of the photolysis zone show that C2 is produced in various electronic states and energetic consideration require that dissociation of C6H6 must involve two or more photons at 266 nm. 3WM spectra of C6D6 are identical to those of C6H6 in the anti-Stokes shift region near 3000 cm−1 and hence the transients do not contain CH bonds. 3WM spectra of C2H2 fragments are quite similar to those of benzene in the 3000 cm−1 region so that C2 is believed to be responsible for both 3WM and fluorescence spectra. The 3WM spectra cannot be interpreted in terms of simple CARS vibrational resonances of C2. Intensity considerations suggest that enhancement due to multiple resonance is likely, and various electronic–electronic and vibrational–electronic 3WM processes are discussed.
Large deployable space-based optical systems will likely require complex structure position controls in conjunction with an adaptive optic to maintain optical tolerances necessary for near diffraction-limited performance. A real-time holographic (RTH) compensation system can greatly reduce the requirements and complexity of the position control system and enable the use of novel or imperfect optical components for large mirror surfaces. A hologram of the distorted primary is recorded with a local beacon at 532 nm (-100 nJ/exposure) on an optically addressed spatial light modulator and transferred as a phase grating to a ferroelectric liquid crystal layer. The hologram is played back with target light containing the same optical distortion. A corrected image is obtained in the conjugate diffracted order where the phase of the optical distortion is subtracted from the distorted image. We report recent test results and analysis of a RTH-compensated deformed mirror of 0.75 m diameter. The short exposure hologram is recorded at video frequencies (30 Hz) at bandwidths up to 5 kHz.Correction for tens of waves of static and dynamic optical distortions including mechanical and thermal warp, mechanical vibration, and air turbulence are shown for monochromatic (532 nm) and broadband (532 nm) illuminated targets.
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