Nitric oxide concentration measurements in atmospheric pressure flames using electronic-resonance-enhanced coherent anti-Stokes Raman scattering

We report the application of electronic-resonance-enhanced coherent anti-Stokes Raman scattering (ERE-CARS) for measurements of nitric oxide concentration ([NO]) in three different atmospheric pressure flames. Visible pump (532 nm) and Stokes (591 nm) beams are used to probe the Q-branch of the Raman transition. A significant resonance enhancement is obtained by tuning an ultraviolet probe beam (236 nm) into resonance with specific rotational transitions in the (v’=0, v”=1) vibrational band of the A²Σ⁺–X²Π electronic system of NO. ERE-CARS spectra are recorded at various heights within a hydrogen-air flame producing relatively low concentrations of NO over a Hencken burner. Good agreement is obtained between NO ERE-CARS measurements and the results of flame computations using UNICORN, a two-dimensional flame code. Excellent agreement between measured and calculated NO spectra is also obtained when using a modified version of the Sandia CARSFT code for heavily sooting acetylene-air flames (φ=0.8 to φ=1.6) on the same Hencken burner. Finally, NO concentration profiles are measured using ERE-CARS in a laminar, counter-flow, non-premixed hydrogen-air flame. Spectral scans are recorded by probing the Q₁ (9.5), Q₁ (13.5) and Q₁ (17.5) Raman transitions. The measured shape of the [NO] profile is in good agreement with that predicted using the OPPDIF code, even without correcting for collisional effects. These comparisons between [NO] measurements and predictions establish the utility of ERE-CARS for detection of NO in flames with large temperature and concentration gradients as well as in sooting environments. PACS 07.88.+y; 42.62.Fi; 42.65.Dr     

Experimental and Computational Study of the Thermal Decomposition of 3‐Methyl‐3‐buten‐1‐ol in m‐Xylene Solution

An experimental study of the thermal decomposition of a β‐hydroxy alkene, 3‐methyl‐3‐buten‐1‐ol, in m‐xylene solution, has been carried out at five different temperatures in the range of 513.15–563.15 K. The temperature dependence of the rate constants for the decomposition of this compound in the corresponding Arrhenius equation is given by ln k (s^?1) = (25.65 ± 1.52) ? (17,944 ± 814) (kJ·mol^?1)·T^?1. A computational study has been carried out at the M05–2X/6–31+G(d,p) level of theory to calculate the rate constants and the activation parameters by the classical transition state theory. There is a good agreement between the experimental and calculated rate constants and activation Gibbs energies. The bonding characteristics of reactant, transition state, and products have been investigated by the natural bond orbital analysis, which provides the natural atomic charges and the Wiberg bond indices. Based on the results obtained, the mechanism proposed is a one‐step process proceeding through a six‐membered cyclic transition state, being a concerted and slightly asynchronous process. The results have been compared with those obtained previously by us (Struct Chem 2013, 24, 1811–1816) for the thermal decomposition of 3‐buten‐1‐ol, in m‐xylene solution. We can conclude that in the compound studied in this work, 3‐methyl‐3‐buten‐1‐ol, the effect of substitution at position 3 by a weakly activating CH₃ group is the stabilization of the transition state formed in the reaction and therefore a small increase in the rate of thermal decomposition.     

Structural and Kinetic Aspects of Blood Plasma Protein Adsorption on the Surface of Hydrophobic Polymers

Abstract

Due to the wide use of polymers in medicine, researchers are required to solve a very important problem–to understand the interaction between materials of nonphysiological origin and the surrounding biological liquids, and tissues, particularly blood.     

Energy levels of 56Co studied by the 58Ni(d, α)56Co reaction near 0°

Tensor analyzing powers, T₂₀, of outgoing α-particles in the ⁵⁸Ni($\text{d}$, α)⁵⁶Co reaction at detection angles near 0° have been measured for excited states in ⁵⁶Co for beam energies of 6.75, 7.0, 7.5, 9.0 and 9.5 MeV. Thirty-seven spin-parity combinations for ⁵⁶Co excited states have been deduced. Previous J^π ambiguities for 11 of these states have been eliminated, and results in conflict with existing assignments for the levels at 3.235 and 3.378 MeV have been obtained. A search for 0⁺ states was carried out from angular distribution measurements at forward angles of the unpolarized (d, α) reaction. The combined results from this and previous experiments were found to be in reasonable agreement with calculated level schemes.     

Synthesis of a eta 2-2,3-diphosphabutadiene complex of zerovalent platinum from the corresponding eta 2-phosphaalkyne complex

Hydrozirconation of the eta 2-phosphaalkyne complex [Pt(dppe)(eta 2-tBuCP)] with [ZrHCl(eta 5-C5H5)2], followed by treatment with the chlorophosphaalkene ClP=C(SiMe3)2 affords the eta 2-2,3-diphosphabutadiene complex [Pt(dppe)(eta 2-tBuC(H)=PP=C(SiMe3)2]. In the presence of [Pt(PPh3)2] the latter undergoes an addition reaction with water to afford the structurally characterised Pt(II) complex [Pt(dppe)(tBuCH2P(O)HPC(SiMe3)2].     

The selection rule in (d, α) reactions leading to 0+ antianalogue states in odd-odd nuclei

We point out that, in many cases, anti-analogue 0⁺ states cannot be populated in )d, α) reactions. This results from the particular isospin structure of the anti-analogue, and may well be new, useful, tool to aid in the identification of such states. A particular example arising in the ⁴² Ca (d, α) reaction is generalized in a straightforward way.     

Spin-parity assignments for 66Cu levels via the 68Zn(d, α)66Cu reaction

The ⁶⁸Zn($\text{d}$, α)⁶⁶Cu reaction populating low-lying states in ⁶⁶Cu has been studied at θ_lab = 4° using deuteron beams in the energy range 9.0 to 10.5 MeV. Tensor analyzing powers were calculated and natural- or unnatural-parity assignments were made for thirteen states in ⁶⁶Cu. By combining these results with existing limits unambiguous J^π assignments of 2⁺, 2⁺, 2⁺ and 1⁺ have been made for the levels at 186, 465, 822 and 1344 keV respectively. The previous tentative assignments to seven other levels have been confirmed while that for the 1247 keV level has been shown to be incorrect. The identification of the quartet of levels based on the $\text{π(}\text{P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{)v(}\text{f}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{)}$ configuration has been confirmed.