Ultra-large bandwidth hollow-core guiding in all-silica Bragg fibers with nano-supports

We demonstrate a new class of hollow-core Bragg fibers that are composed of concentric cylindrical silica rings separated by nanoscale support bridges. We theoretically predict and experimentally observe hollow-core confinement over an octave frequency range. The bandwidth of bandgap guiding in this new class of Bragg fibers exceeds that of other hollow-core fibers reported in the literature. With only three rings of silica cladding layers, these Bragg fibers achieve propagation loss of the order of 1 dB/m.Comment: 9 pages including 5 figure

SPECTROSCOPY AND PHOTODISSOCIATION DYNAMICS OF HYDROCARBON RADICALS: ALLYL, PROPARGYL, AND ETHYL

Author Institution: Department of Chemistry, Laboratorium fuer Organische ChemiePolyatomic radicals are uniquely favorable for investigations of dissociation dynamics because of their simple electronic structure and low energy dissociation limits. They are furthermore important intermediates in a variety of gas-phase processes of practical importance, such as combustion and chemical vapor deposition. Building on earlier spectroscopic work from our group, we report the picosecond and nanosecond dissociation dynamics of three radicals that represent three important cases. A combination of time- and energy-resolved work identifies the product channels and allows the extraction of microcanonical rates over a wide range of internal energies. These are compared to the results of high-level ab initio calculations and statistical models. A solution is proposed for the anomalous behavior of ethyl radical

Photoionization and dissociative photoionization of the allyl radical, C3H5

International audienceThe photoionization and dissociative photoionization of the allyl radical in the VUV range was investigated using synchrotron radiation. Allyl radicals were generated by flash pyrolysis from allyl iodide and 1,5-hexadiene. Mass spectra show the appearance Of C3H3+ as a fragment in the dissociative photoionization of allyl above 10 eV. Between 10.4 and 10.5 eV the C3H3+ signal reaches 50% of its maximum value. Cyclopropenyl cation, c-C3H3+, is the thermochemically most stable product, but accompanying ab initio computations indicate that formation of linear 1-C3H3+ becomes competitive at small excess energies. The dissociative photoionization of the precursor molecules is discussed as well. An ionization energy of 8.13 +/- 0.01 eV was deduced from threshold photoelectron spectra

The vacuum ultraviolet photochemistry of the allyl radical investigated using synchrotron radiation

International audienc