Reactions of N(2²D) with CH₃OH and Its Isotopomers

Abstract

The reaction pathways of N(2D) with methanol and its isotopomers were specified by laser pump-and-probe experiments and molecular orbital calculations. It was shown experimentally that CH3OH deactivates N(2D) efficiently to produce ground-state NH and OH radicals. The nascent state distributions of these radicals are not statistical, suggesting that the intermediate species decompose before energy randomization. A similar result was obtained for ND and OD formed in the N(2D)/CD3OD system. NH, ND, OH, and OD radicals were identified in partially deuterated systems. The ND/NH population ratio measurements show that NH and ND radicals are produced from both hydroxyl and methyl positions, but the former plays more important roles, one order of magnitude, than the latter. This is consistent with the result of ab initio molecular orbital calculations that the most favorable initial step is the addition of N(2D) to the O atom. The OD/OH ratio in the CD3OH system as well as the OH/OD ratio in the CH3OD system is 0.5. OH(OD) is produced mainly by the C−O bond scission just after the insertion of N(2D) into a C−H(C−D) bond, but the bond scission after intramolecular H/D scrambling is also important. This is also consistent with the result of calculations that the barrier height for the H(D) atom migration is much lower than the available energy.

The difference of equilibrium melting point between poly(l‐lactic acid) and poly(l‐lactic acid)/poly(d‐lactic acid) blends: cases with three molecular weights

“…[32][33][34] In addition, it was reported that the chains with lower M n prefer extended chain crystallization (ECC) while chains with higher M n prefer folded chain crystallization. 35,36 Considering the alternate arrangement of PLLA and PDLA chains in the lattice, SC is a typical example of intermolecular crystal nucleation and growth; 24 meanwhile, SC prefers the ECC model even with higher M n . Thus, for the PLA samples with higher M n , PLLA adopts the ECC model to a larger extent than the PLLA/PDLA blends.…”

Multiple melting behavior of poly(butylene succinate). II. Thermal analysis of isothermal crystallization and melting process

“…It has been clarified that T c dependence of the radius growth rate of spherulites (G vs. T c ) shows a bellshaped curve, and that this dependence is expressed by an exponential function, including T c . 26,27 Recently, Umemoto et al 28,29 investigated G versus T c for various polymers and reported the bell-shaped G versus T c curve of poly(ethylene succinate) (PESu) that is a homologue of PBSu Miyata and Masuko 3 obtained the G versus T c of the PBSu film sample. However, no peak appeared in their G versus T c curve, because their G versus T c was obtained above 90 8C.…”

Relationship between Oxygen Additive Amount and Photoresist Removal Rate Using H Radicals Generated on an Iridium Hot-Wire Catalyst

“…Our earlier report demonstrated that the removal rate of a novolak photoresist increases in proportion to the H-radical density [19]. The rate of removal by H radicals at 1.0% must be much smaller than that in the pure hydrogen system because the H-radical density was reduced to less than one-half that without oxygen [9]. However, O and OH radicals are also produced with H radicals when oxygen is added.…”

“…To overcome the limitation, we examined a way of adding a trace amount of oxygen gas to the atmosphere in which H radicals are produced. According to Umemoto and Moridera [9], not only H radicals but also O and OH radicals can be produced by activating mixtures of hydrogen and oxygen on a tungsten hot-wire surfaces in the absence of photoresists. Generally speaking, OH radicals are highly reactive and thereby may improve the rate [10,11].…”

“…This increase can easily be explained by the removal by OH radicals. This decrease may be due to the decrease in the production rate of H radicals by the catalytic poisoning of O atoms on the catalyst surface [9]. The added oxygen amount is limited to a small amount when using a W catalyst because of its poor oxidation resistance.…”