The relationship between IR characteristic peak and microstructure of the glass used as optical fiber

Based on the harmonic vibration equation, the relationship between IR characteristic peak of fiberglass and Si-O-Si bond angle was deduced, and 1 100 cm^-1 characteristic peak was specifically studied. It is found that 1 100 cm^-1 characteristic peak shifts to higher wave number when Si-O-Si bond angle increases. Taking fused biconical taper （FBT） coupler as an example, the microstructures of the fiber coupler manufactured at different draw- ing speeds were tested with micro infrared spectrum. According to the test results, it is found that the bond angle at the taper region is the largest, the one at the fused region is the second largest, and the one of bare fiber is the smal- lest. The characteristic peaks of fused-taper region shift to higher wave number when drawing speed increases.

O2-Oxidation of Cyanomethylene Radical:Infrared Identification of Criegee Intermediates syn-and anti-NCC(H)OO

Cyanomethylene radical(HCCN)is an important intermediate in the nitrile chemistry in both the earth’s and the Titan’s atmosphere.Despite that the mechanism for the oxidation of HCCN has been already computationally explored,the key Criegee intermediate,NCC(H)OO,remains unobserved yet.By photolyzing mixtures(1:50:1000)of either HC(N2)CN/O2/N2(266 nm)or HCCNCO/O2/N2(193 nm)at 15.0 K,the elusive carbonyl oxides NCC(H)OO,in syn-and anti-conformations,have been generated and characterized with IR spectroscopy.The spectroscopic identification is supported by ^18O-labeling experiments and the quantum chemical calculations at the BP86/6-311++G(3df,3pd)level.Upon subsequent UV-light irradiation,both conformers of NCC(H)OO further react with O2 and yield NCC(O)H and O3,whereas,the dioxirane isomer HC(O2)CN,which is lower than syn-NCC(H)OO by 23.7 kcal/mol at the CCSD(T)-F12a/aug-cc-pVTZ//BP86/6-311++G(3df,3pd)level,was not observed experimentally.