Intercomparison of IBBCEAS, NitroMAC and FTIR analyses for HONO, NO₂ and CH₂O measurements during the reaction of NO₂ with H₂O vapour in the simulation chamber CESAM

We report on applications of the ultraviolet-light-emitting-diode-based incoherent broadband cavity-enhanced absorption spectroscopy (UV-LED-IBBCEAS) technique for optical monitoring of HONO, NO2 and CH2O in a simulation chamber. Performance intercomparison of UV-LED-IBBCEAS with a wet chemistry-based NitroMAC sensor and a Fourier transform infrared (FTIR) spectrometer has been carried out on real-time simultaneous measurement of HONO, NO2 and CH2O concentrations during the reaction of NO2 with H2O vapour in CESAM (French acronym for Experimental Multiphasic Atmospheric Simulation Chamber). The 1σ (signal-to-noise ratio (SNR) = 1) detection limits of 112 pptv for NO2, 56 pptv for HONO and 41 ppbv for CH2O over 120 s were found for the UV-LED-IBBCEAS measurement. On the contrary to many set-ups where cavities are installed outside the simulation chamber, we describe here an original in situ permanent installation. The intercomparison results demonstrate that IBBCEAS is a very well suitable technique for in situ simultaneous measurements of multiple chemically reactive species with high sensitivity and high precision even if the absorption bands of these species are overlapped. It offers excellent capacity for non-invasive optical monitoring of chemical reactions without any perturbation. For the application to simulation chambers, it has the advantage to provide a spatially integrated measurement across the reactor and hence to avoid point-sampling-related artefacts.

Investigation of binary chemical reaction in magnetohydrodynamic nanofluid flow with double stratification

This article addresses MHD nanofluid flow induced by stretched surface. Heat transport features are elaborated by implementing double diffusive stratification. Chemically reactive species is implemented in order to explore the properties of nanofluid through Brownian motion and thermophoresis. Activation energy concept is utilized for nano liquid. Further zero mass flux is assumed at the sheet’s surface for better and high accuracy of the out-turn. Trasnformations are used to reconstruct the partial differential equations into ordinary differential equations. Homotopy analysis method is utilized to obtain the solution. Physical features like flow, heat and mass are elaborated through graphs. Thermal stratified parameter reduces the temperature as well as concentration profile. Also decay in concentration field is noticed for larger reaction rate parameter. Both temperature and concentration grows for Thermophoresis parameter. To check the heat transfer rate, graphical exposition of Nusselt number are also discussed and interpret. It is noticed that amount of heat transfer decreases with the increment in Hartmann number. Numerical results shows that drag force increased for enlarged Hartmann number.

Recent Advances in the Plasma-Assisted Synthesis of Zinc Oxide Nanoparticles

An overview of recent work on the low-temperature plasma-assisted synthesis of zinc oxide (ZnO) nanoparticles is presented and interpreted in terms of gas-phase and surface reactions with illustrated examples. The thermodynamical nonequilibrium conditions allow the formation of chemically reactive species with a potential energy of several eV, which readily interact with the Zn precursors and initiate reactions leading to the formation of nanoparticles or nanowires. The high-quality nanowires were synthesized from Zn powders only upon interaction with moderately ionized plasma in a narrow range of plasma parameters. This technique is promising for the synthesis of large quantities of nanowires with aspect ratios well above 10, but the exact range of parameters remains to be determined. Apart from the ex situ techniques, the ZnO nanoparticles can be synthesized by depositing a film of precursors (often Zn salts or Zn-containing organometallic compounds) and exposing them to oxygen plasma. This technique is useful for the synthesis of well-adherent ZnO nanoparticles on heat-sensitive objects but requires further scientific validation as it often leads to the formation of a semicontinuous ZnO film rather than nanoparticles. Both low-pressure and atmospheric plasmas are useful in converting the precursor film into ZnO nanoparticles despite completely different mechanisms.

Intercomparison of IBBCEAS, NitroMAC and FTIR for HONO, NO₂ and HCHO measurements during the reaction of NO₂ with H₂O vapor in the atmospheric simulation chamber of CESAM

We report on applications of ultraviolet light emitted diode based incoherent broadband cavity enhanced absorption spectroscopy (UV-LED-IBBCEAS) technique for optical monitoring of HONO, NO2 and CH2O in a simulation chamber. Performance intercomparison of the UV-LED-IBBCEAS with a wet chemistry-based NitroMAC sensor and a FTIR spectrometer has been carried out on real time simultaneous measurement of HONO, NO2 and CH2O concentrations during the reaction of NO2 with H2O vapor in the CESAM atmospheric simulation chamber. 1-σ (SNR = 1) detection limits of 200 pptv for NO2, 100 pptv for HONO and 5 ppbv for CH2O over 120 s were found for the UV-LED-IBBCEAS measurement. On the contrary to many set-ups where cavities are installed outside the simulation chamber, we describe here an original in-situ permanent installation. The intercomparison results demonstrate that IBBCEAS is a very well suitable technique for in situ simultaneous measurements of multiple chemically reactive species with high sensitivity and high precision even if the absorption bands of these species are overlapped. It offers excellent capacity to non-invasive optical monitoring of chemical reaction without any perturbation. For the application to simulation chamber, it has the advantage to provide a spatially integrated measurement across the reactor and hence to avoid point sampling related artefact.