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Heterogeneity in seasonal aerosol types due to different sources, local characteristics, and meteorology lead to different optical and radiative properties from one place to another. This study analyzes the long-term averages of aerosol optical and radiative properties obtained by the Aerosol Robotic Network (AERONET) version 3 at four sites in Indonesia representing fire prone areas (Palangka Raya, Pontianak, Jambi: 2012–2020), and urban-industrial (Bandung: 2009–2018). We examined the seasonal variation of aerosol optical depth (AOD), Angstrom Exponent (AE), Precipitable Water Vapor (PWV), and Single Scattering Albedo (SSA) combined with meteorological parameters at these Indonesian sites. Multiple clustering techniques from different relationships among various aerosol optical and radiative parameters was employed to further study the aerosol type in respect to different seasonality. The results exhibited a distinct seasonal pattern at all sites except Bandung, whereas AOD increased owing to forest and peat fire outbreaks during the dry season. The trend in AOD annual depicts an increase in Bandung as emission from urban/industrial increases episodically, while it depicts a decrease at the three biomass burning sites. As AOD increased, Palangka Raya, Pontianak, and Jambi exhibited wider ranges of observed AE (1.2–1.8) and high FMF (>0.8) in the dry burning period (June to October). On the other hand, Bandung has more aerosol distribution in the range of FMF values 0.6–1 and AE 1–1.6, compared with other sites, suggesting contribution of complex aerosol emission from different sources and likely due to the formation of secondary aerosol production from trace gases. Palangka Raya, Pontianak, and Jambi exhibited non-absorbing characteristics, as indicated by high SSA (>0.95), high FMF, and high EAE values (1.2–1.7) with no discrepancy in seasonal patterns, implying that biomass burning aerosols in Indonesia tend to cool the atmosphere with strong scattering rather than absorbing. At Bandung, aerosols mixed with slightly absorbing and non-absorbing aerosols owing to urban and industrial emissions. This study lays a foundation for further research on the contribution of aerosol radiative forcing to climate within the complex aerosol and cloud environments in Indonesia. • Long-term analysis of aerosol optical and radiative properties combined with the climatic condition in Indonesia. • Decreasing (increasing) tendency of interannual AOD at biomass burning (urban) sites. • Indonesia biomass burning aerosol has non-absorbing properties. • Bandung urban aerosols were mixed with slightly absorbing and non-absorbing. [ABSTRACT FROM AUTHOR]

Using mid-infrared laser absorption spectroscopy, we investigated the room-temperature pressure broadening coefficients for hydroperoxyl radicals (HO 2 ) in nitrogen and oxygen over the 1060.0–1065.5 cm −1 range of the ν 3 band. The HO 2 radicals were produced by flash photolysis of a chlorine/1,4-cyclohexadiene/oxygen mixture. The 20 measured absorption profiles were analyzed with Voigt functions. Air broadening coefficients were estimated from the nitrogen- and oxygen-broadening results and compared with previous results. We discuss the dependence of air broadening on rotational states. [ABSTRACT FROM AUTHOR]

The energy transfer rates between phonons and vibrons in the “doorway region” could be the rate-determining step for impact-induced detonation of molecular crystalline explosives. To investigate the relationship between impact sensitivities and energy transfer, the overall rate of energy transfer in the doorway region is estimated on the basis of a simple theory in which the rate is proportional to a product of the number of states and the rate of population relaxation. We estimated frequencies of normal mode vibrations of PETN, β-HMX, RDX, Tetryl, TNT, FOX-7, m-DNB, ANTA, PN, NQ, NTO, and DMN by means of density functional theory calculations at the B3LYP/6-31G(d) level of theory. Normal mode vibrations of TATB were evaluated by using empirical intra-molecular potentials. The number of doorway modes in the regions of 200 to 700 cm−1 was evaluated by the direct counting method. It is found that the number of doorway modes shows a strong correlation with impact sensitivities obtained by drop hammer tests. This can be explained by the theory, if we assume that the rate of population relaxation is almost the same for all of the explosives investigated in the present work. This assumption is consistent with recent experimental measurements of energy transfer rates of explosives at low temperatures. [Copyright &y& Elsevier]

Gas-phase reactions of simple silicon hydride species underlying many types of chemical vapor deposition processes for silicon-based thin-film growth are reviewed in this paper. Mass spectrometry and laser-based spectroscopy are applied to identify gas-phase intermediates in thermal and hot-wire chemical vapor deposition processes. The mechanism of the thermal decomposition of silanes, including reactions that lead to the formation of hydrogenated silicon clusters, is examined. The gas-phase chemical kinetic mechanism in hot-wire chemical vapor deposition is proposed to explain precursor molecules for the film growth. [Copyright &y& Elsevier]

Simultaneous measurements of on-road and in-vehicle NO and NO 2 levels, particle number concentrations (PNCs), and particles size distributions were performed while driving using a test vehicle equipped with real-time sensors. The results obtained on regional roads showed that heavy-duty vehicles in traffic seem to have a major impact on on-road air quality. Measurements on highways that included a 10 km tunnel and a 2 km uphill section of road indicated that sub-50 nm particles have different features from the other species because of their higher volatility. The other species showed quite high on-road concentrations in the tunnel. In-vehicle conditions were made similar to the on-road ones by setting the air conditioning (AC) mode to the fresh air mode. The in-vehicle NO 2 concentration in the tunnel was over 0.50 ppmV, which is almost five times higher than the 1-hour ambient air quality standard proposed by the World Health Organization (WHO). In sections other than the tunnel, the in-vehicle NO 2 concentration was almost the same as the 1-hour WHO standard. Higher on-road NO 2 /NOx ratios than those of exhaust gases and different behavior of sub-50 nm particles from other species suggested that NO 2 and sub-50 nm particles were mainly due to secondary products formed by atmospheric reactions. [ABSTRACT FROM AUTHOR]

Abstract: Direct absorption spectra of methane (12CH4 and 13CH4) at room temperature have been recorded using a 2.4-μm distributed feedback laser. Integrated cross-sections of 13CH4 were measured and compared with those listed in the HITRAN 2008 and 2012 databases, indicating that there are some discrepancies between our results and both editions of the HITRAN database. The pressure-broadening parameters of those 13CH4 lines in synthetic air were also examined experimentally. For the purpose of determining the carbon isotope ratio (13CH4/12CH4) through the spectral measurements, candidate line pairs of 12CH4 and 13CH4 within the range 4147–4154cm−1 were explored. Resultantly, the well-isolated line pair of 12CH4 at 4151.843cm−1 and 13CH4 at 4151.966cm−1 was suggested to be a candidate for determining the carbon isotope ratio of CH4 in this wavenumber region. [Copyright &y& Elsevier]

Abstract: Time-resolved measurements of HO2 and OH have been conducted in 355nm photolysis of dimethyl ether/Cl2/O2 mixture at elevated temperature, using near-infrared frequency modulation spectroscopy. A part of OH was found to be produced at a timescale of several microseconds by the methoxymethyl with O2 reaction, while HO2 is formed mainly in milliseconds with the yield increasing up to 60% between 500 and 600K. It was rationalized that HO2 is not a direct product of the O2 adduct decomposition, but a secondary product through HCHO+OH reaction. Another pathway through HCO formation from the adduct is also discussed. [Copyright &y& Elsevier]

A time-step model was constructed to estimate the amount of evaporative emissions from vehicular diurnal breathing loss (DBL) on the basis of fuel adsorption–desorption experiments for several carbon canisters attached to seven gasoline vehicles using a chassis dynamometer. Experimental results showed that the canister's total volatile organic compound (VOC) storage ability is proportional to the canister volume, and a canister's desorption ability strongly depends on the amount of VOC trapped in the canister and the air purge flow rate of each vehicle. These properties were formulated into equations by regression analysis and used with the material balance inside the canister to propose a model for estimating emissions after carbon canister breakthrough, which are a function of a vehicle's driving and parking frequency. The model was applied to DBL experimental results derived from our previous studies to confirm its validity. Better agreement between the model and the previous experimental results was obtained when appropriate parameters were set. The proposed model is expected to contribute to estimating the VOC emission inventory for gasoline vehicles. Unlabelled Image • We measured carbon canister adsorption ability for gasoline vehicles. • Canister purge ability was measured using a chassis dynamometer. • We propose a model that estimates evaporative emissions from vehicles. • The proposed model closely replicates our previous experimental results. • Our model will contribute to estimating the VOC emission inventory. [ABSTRACT FROM AUTHOR]

The effects of Reid vapor pressure (RVP) on refueling emissions and the effects of ethanol 10% (E10) fuel on refueling and evaporative emissions were observed using six cars and seven fuels. The results indicated that refueling emissions can be reproduced by a simple theoretical model in which fuel vapor in the empty space in the tank is pushed out by the refueling process. In this model, the vapor pressures of fuels can be estimated by the Clausius–Clapeyron equation as a function of temperature. We also evaluated E10 fuel in terms of refueling and evaporative emissions, excluding the effect of contamination of ethanol in the canister. E10 fuel had no effect on the refueling emissions in cases without onboard refueling vapor recovery. E10 showed increased permeation emissions in evaporative emissions because of the high permeability of ethanol. And with E10 fuel, breakthrough emissions appeared earlier but broke through slower than normal fuel. Finally, canisters could store more fuel vapor with E10 fuel. [ABSTRACT FROM AUTHOR]

In this study, we conducted seven-day diurnal breathing loss (DBL) tests on gasoline vehicles. We propose a model based on the theory of thermodynamics that can represent the experimental results of the current and previous studies. The experiments were performed using 14 physical parameters to determine the dependence of total emissions on temperature, fuel tank fill, and fuel vapor pressure. In most cases, total emissions after an apparent breakthrough were proportional to the difference between minimum and maximum environmental temperatures during the day, fuel tank empty space, and fuel vapor pressure. Volatile organic compounds (VOCs) were measured using a Gas Chromatography Mass Spectrometer and Flame Ionization Detector (GC-MS/FID) to determine the Ozone Formation Potential (OFP) of after-breakthrough gas emitted to the atmosphere. Using the experimental results, we constructed a thermodynamic model for estimating the amount of evaporative emissions after a fully saturated canister breakthrough occurred, and a comparison between the thermodynamic model and previous models was made. Finally, the total annual evaporative emissions and OFP in Japan were determined and compared by each model. [ABSTRACT FROM AUTHOR]

Highlights: [•] We measured stable carbon isotope ratios of CO2 by a laser absorption spectrometer. [•] The H2O broadening coefficients of CO2 were determined. [•] The effect of humidity on δ13C determination was examined. [•] The spectrometer keeps constant measurement conditions over 12-h periods. [ABSTRACT FROM AUTHOR]

Abstract: In situ measurements of nitrogen dioxide (NO2) concentrations were conducted at an urban site in Tokyo (35°71′N, 139°76′E), Japan during the summers of 2007–2009. A chemiluminescence instrument equipped with a molybdenum oxide converter (Mo-CL) and a laser-induced fluorescence (LIF) instrument were used simultaneously for determining the ambient NO2 concentrations. A tight linear correlation between the NO2 concentrations determined by the LIF and Mo-CL techniques was evident except for high ozone concentration periods over 50 ppbv. During the high ozone episodes, correlation plots of the NO2 concentrations between Mo-CL and LIF techniques indicated an overestimation of Mo-CL NO2. To examine in detail the systematic differences between two techniques, a thermal dissociation laser-induced fluorescence (TD-LIF) instrument was employed in the summer of 2009 to measure total peroxy nitrates (ΣPNs) and total reactive nitrogen (NO z ). We found that the ΣPNs concentrations correlated well with the discrepancies in NO2 concentrations determined by the Mo-CL and LIF techniques. This result suggests that peroxy nitrate species significantly contribute to the observed interference in the Mo-CL measurements under high O3 concentrations in our observation at the urban site in Tokyo. [Copyright &y& Elsevier]

Abstract: A highly sensitive cavity ring-down spectrometer (CRDS) was used to monitor the aerosol extinction coefficient at 532nm. The performance of the spectrometer was evaluated using measurements of nearly monodisperse polystyrene particles with diameters between 150 and 500nm. By comparing the observed results with those determined using Mie theory, the accuracy of the CRDS instrument was determined to be >97%, while the upper limit for the precision of the instrument was estimated to be 0.6–3.5% (typically 2%), depending on the particle number concentration, which was in the range of 30–2300particlescm−3. Simultaneous measurements of the extinction (b ext), scattering (b sca) and absorption (b abs) coefficients of ambient aerosols were performed in central Tokyo from 14 August to 2 September 2007 using the CRDS instrument, two nephelometers and a particle/soot absorption photometer (PSAP), respectively. The value of b ext measured using the CRDS instrument was compared with the sum of the b sca and b abs values measured with a nephelometer and a PSAP, respectively. Good agreement between the b ext and b sca + b abs values was obtained except for data on days when high ozone mixing ratios (>130ppbv) were observed. During the high-O3 days, the values for b sca + b abs were ∼7% larger than the value for b ext, possibly because the value for b abs measured by the PSAP was overestimated due to interference from coexisting non-absorbing aerosols such as secondary organic aerosols. [Copyright &y& Elsevier]