Irradiation response of mobile protons in buried SiO{sub 2}

Trapping of mobile protons is observed in various SOI materials, but only upon irradiating under a positive top Si bias. Thermal detrapping shows that the proton traps are shallow and located near the substrate Si/SiO{sub 2} interface

A quantum mechanical investigation of positively charged defects in SiO{sub 2} thin film devices

Ab initio Hartree-Fock and second-order Moeller-Plesset theory calculations have been performed to investigate the stability of triply-coordinated O{sup +} centers in the Si-O-Si network of amorphous SiO{sub 2}. The calculations reveal that the H{sup +} ion binds with a bridging O center to form a very stable (D{sub e} > 6 eV) trivalent O complex. Capture of an electron by the positively charged protonated complex, however, is predicted to immediately lead to the dissociation of the O-H bond. A relatively weaker, but stable bond is also formed between the bridging O atom and a {sup +}SiH{sub 3} ion

Microscopic structure of E{sub {delta}}` center in amorphous SiO{sub 2}: A first principles quantum mechanical investigation

We report the first ab initio quantum mechanical investigation of the structure of the E{sub {delta}}` center in a-SiO{sub 2}. Our calculations suggest that the unpaired electron is shared by only two Si atom, irrespective of the Si cluster size

Ab initio configuration-interaction studies of the ground state potential energy and hyperfine coupling constants of 35^{35}Cl2−_2^-

Potential energy and spectroscopic constants for the X$^2 \sum^+ _\mu$ ground state of a;, were calculated by configuration-interaction (Cl) methods, using large basis sets with polarization and diffuse functions. From these CI wavefunctions, the isotropic (a$_{iso}$) and dipolar (A$_{dip}$) components of the hyperfine coupling constant were obtained. The effects of various s, p basis sets, polarization and diffuse functions, as well as the influence of reference configurations and configuration selection thresholds were investigated. The best values obtained are 35·31 G for a$_{iso}$ and 29·440 for A$_{dip}$• tobe compared with experimental values of 37 ± 1 G and 32 ± 1 G, respectively. It is shown that the contributions to a1so of the K and L shells are opposite in sign, differing by about 4 G. Upon vibrational averaging, both a$_{iso}$ and A$_{dip}$ move towards smaller values as v increases. An adiabatic electron affinity of 2·46eV was obtained for CL$_2$ , and a vertical electron detachment energy of 3·71 eV for Cl;

Second-Order Nonlinear Optical Effects in Novel Side-Chain Liquid Crystalline Polymers and Monomers Under Bias of an Applied DC Electric Field

Second-order nonlinear optical susceptibilities of a series of newly synthesized liquid crystalline polymers and corresponding monomers were measured by using second-harmonic generation. A substituted stilbene moiety was selected as the main conjugated π-electronic structure, and systematic modifications were made at the site of the donor and in the conjugation path to compare the roles of various donors and charge-transferring linkages in the second-harmonic-generation process. The β values extracted from the measurements made on solutions and on thin films yielded similar values for the monomers and the corresponding polymers. The variations in β values are discussed in terms of molecular structural properties, charge-transferring power of the donors, and dispersion effect

Nonlinear optical properties of chiral liquids: electric-dipolar pseudoscalars in nonlinear optics

We give an overview of linear and nonlinear optical processes that can be specific to chiral molecules in isotropic media. Specifically, we discuss the pseudoscalars that underlie nonlinear optical activity and chiral frequency conversion processes in fluids. We show that nonlinear optical techniques open entirely new ways of exploring chirality: Sum-frequency-generation (SFG) at second-order and BioCARS at fourth-order arise in the electric-dipole approximation and do not require circularly polarized light to detect chiral molecules in solution. Here the frequency conversion in itself is a measure of chirality. This is in contrast to natural optical activity phenomena which are based on the interference of radiation from induced oscillating electric and magnetic dipoles, and which are observed as a differential response to right and left circularly polarized light. We give examples from our SFG experiments in optically active solutions and show how the application of an additional static electric field to sum-frequency generation allows the absolute configuration of the chiral solute to be determined via an electric-dipolar process. Results from ab initio calculations of the SFG pseudoscalar are presented for a number of chiral molecule