Melvin P. Nadler

Synthesis of polyazapolycyclic caged polynitramines

Abstract Syntheses of new polyazapolycyclic caged polynitramines are described. Sequentially reacting 4,10-dibenzyl-2,6,8,12-tetraacetyl-2,4,6,8,10,12-hexaazaisowurtzitane (5a) with NOBF4 and NO2BF4 in sulfolane solvent produces 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo-[5.5.0.05,9.03,11]dodecane, 6). Syntheses of two new polyazapolycyclic caged trinitramines, 3,5,12-trinitro-3,5,12-triazawurtzitane (7a) and 2,4,10-trinitro-2,4,10-triazaadamantane (12a), as well as their labile parent secondary amines, are discussed. A new caged polynitrosamine, 3,5,12-trinitroso-3,5,12-triazawurtzitane (7d), has been obtained by ring-cleavage nitrosation of the new hexamine-wurtzitane compound 3,5,7,9-tetraazahexacyclo-[9.3.1.13,7.02,9.04,13.05,10]-hexadecane (10).

Site‐selective excitation and polarized absorption spectra of Nd3+ in Sr5(PO4)3F and Ca5(PO4)3F

Polarized absorption and fluorescence spectra were analyzed to establish individual energy (Stark) levels of Nd3+ ions in host crystals of Sr5(PO4)3F (SFAP) and Ca5(PO4)3F (FAP). Site‐selective excitation and fluorescence facilitated differentiation between Nd3+ ions in emitting sites associated with 1.06 μm stimulated emission, and nonemitting Nd3+ ions in other sites. Measurements were made on samples containing different concentrations of Nd3+ at 4 K and higher temperatures. Substitution of Nd3+ for Sr2+ or Ca2+ was accompanied by passive charge compensation during crystal growth. Crystal‐field splitting calculations were performed according to site for Stark levels of Nd3+ ions identified spectroscopically. We obtained a final set of crystal‐field parameters Bnm for Nd3+ ions in fluorescing sites with a rms. deviation of 7 cm−1 (52 levels in Nd:SFAP) and 8 cm−1 (59 levels in Nd:FAP). For one of the nonemitting sites in Nd:FAP we obtained a final set of Bnm parameters which gave a rms deviation of 6 cm...

Absorption spectra and energy levels of Sm3+:Y3Al5O12

Abstract Absorption spectra between 0.2 and 6.7 μm are reported for trivalent samarium in single-crystal yttrium aluminum garnet, Y 3 Al 5 O 12 , at liquid-helium, liquid-nitrogen, and room temperatures. Energy levels (4f 5 [ SL ] J μ) associated with sextet, quartet, and doublet states of Sm 3+ are established from data between 1500 and 46000 cm −1 . Most samarium ions occupy yttrium ion sites, which have D 2 point-group symmetry in the lattice. A free-ion wavefunction calculation predicts the assignment of 35 isolated [ SL ] J manifolds with an rms deviation of 32 cm −1 between calculated and observed centers of gravity. A hamiltonian consisting of coulombic, spin—orbit, and crystalline electric field (D 2 symmetry) terms is diagonalized for the two lowest sextet states [6H] J and [6F] J . The calculated Stark levels based on a single set of B km crystal field parameters are compared to the observed levels (54) yielding an rms deviation of 4.9 cm −1 .

FT-IR and FT-NMR Study of Organophosphorus Surface Reactions

Fourier transform infrared (FT-IR) and Fourier transform nuclear magnetic resonance (FT-NMR) methods were used to examine the adsorption and reaction of diisopropyl fluorophosphate (DFP) on various solid adsorbents. Static and flow system experiments were monitored with the use of FT-IR to determine DFP adsorption rates and isotherms on silica, coated silicas, γ-alumina, coated aluminas, and activated charcoal. The adsorption of DFP(g) onto the solid adsorbents was generally very rapid, with a half-life of 20 s for 1 mg DFP onto 25 mg of 350 m2/g silica. The DFP adsorption isotherm on silica indicated chemisorption to a monolayer at P/P0 < 0.6, followed by increased coverage that appears to be physical adsorption. Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, photoacoustic spectroscopy (PAS), and solid-state 31P NMR of adsorbed DFP showed chemisorption on silica and on alumina. Bonding at the P=O of DFP was indicated by a −41 cm−1 shift in the v(P=O) and a 1-ppm upfield shift in the 31P resonance. DRIFT, PAS kinetics, and 31P NMR showed that DFP hydrolyzed after the initial adsorption on alumina and some coated materials but not on silica or activated charcoal. The rate of hydrolysis increased on alumina with addition of water and varied with different aluminas and coated silicas.

High-performance electro-optic polymers for high-frequency modulators

New thermally stable, spin-castable, electro-optic (EO) polymers designed for high frequency optical modulators are reported (the third generation accordion polymers). The softening temperature (the glass transition temperature) is about 240 degrees Celsius, and the upper limit on short term thermal baking stability is about 320 degrees Celsius. The refractive index at 1.3 microns is about 1.73 and fairly birefringent. The second-order nonlinear optic coefficient, d33, of a second generation accordion polymer containing essentially the same chromophore, measured by second- harmonic generation at 1.06 microns, is 120 pm/V (resonance enhanced by the 495 nm absorption). Measurement of the electro-optic coefficient, r33, is in progress. The added thermal stability in these polymers is due to the all- aryl amine electron donor. The molecular topology of the polymer backbone makes it possible for over 85 weight percent of the bulk material to be comprised of EO-active chromophore. The chromophores are configured in a head-to- head mainchain topology. The films are completely amorphous (no microcrystalline scattering sites).

Aging in nonlinear optical polymer waveguides

The role that polymers will play as optical waveguides in the photonic communications revolution is described, including examples of polymer photonic devices, physical and optical requirements, aging mechanisms, competing materials, electric-field poled polymer films, room-temperature processed polymer films, and analytical methods for studying physical aging. Several important recent aging studies on nonlinear optical polymers, both thermoplastic and thermoset, are reviewed.