Rayleigh light scattering properties of atmospheric molecular clusters consisting of sulfuric acid and bases

Abstract

The Rayleigh light scattering properties of (H2SO4)a(NH3)b and (H2SO4)a((CH3)2NH)b atmospheric molecular clusters have been investigated using a response theory approach. Using density functional theory the molecular structures and stepwise formation free energies of clusters with a and b up to 4 have been re-investigated. The Rayleigh scattering intensities are calculated from the dipole polarizability tensor α using the CAM-B3LYP functional by applying linear response methods. The intrinsic scattering properties of (H2SO4)a(NH3)b and (H2SO4)a((CH3)2NH)b indicate that amine containing clusters scatter light significantly more efficiently then their ammonia containing counterparts. Using the Atmospheric Cluster Dynamics Code (ACDC) the steady state cluster concentrations are estimated and the effective scattering is calculated. The effective scattering is shown to be highly dependent on the estimated concentrations and indicates that there exist competitive pathways, such as nucleation and coagulation, which influence the cluster distributions. The frequency dependence of the scattering is found to depend on the cluster composition and show increased responses when clusters contain more bases than acid molecules. Based on structures obtained using semi-empirical molecular dynamics simulations the Rayleigh scattering properties of clusters with up to 20 acid-base pairs are evaluated. This study represents the first step towards gaining a fundamental understanding of the scattering properties of small atmospheric clusters in the ambient atmosphere.

Experimental Study on Removal Characteristics of SO3 by Wet Flue Gas Desulfurization Absorber

“…The inlet flue gas temperature exerts a significant effect on SO 3 aerosol formation in a spray scrubber. With the low inlet flue gas temperature, the relative humidity of flue gas increases in the scrubber, thereby forming a supersaturated vapor environment that benefits the SO 3 aerosol coagulation . A portion of SO 3 aerosols with large particle sizes is condensed and coagulated, thereby achieving high removal efficiency.…”

“…With the low inlet flue gas temperature, the relative humidity of flue gas increases in the scrubber, thereby forming a supersaturated vapor environment that benefits the SO 3 aerosol coagulation. 32 A portion of SO 3 aerosols with large particle sizes is condensed and coagulated, thereby achieving high removal efficiency. Therefore, reducing flue gas temperature at the inlet of the scrubber is beneficial to promote the SO 3 aerosol removal efficiency in a certain range.…”

Decomposition of molecular properties

“…26, an excellent approach for Rayleigh scattering of particles in the nanoscale covering the scattering intensities of various incident light frequencies. Going to the other limit, to very small clusters, quantum chemistry methods can be used both for the scattering problem and for the nucleation of the clusters, a recent example being the work of Elm et al 106,107 who used quantum mechanical response theory and a combinatorial sampling approach to study the Rayleigh and hyper-Rayleigh scattering properties of some binary and ternary water clusters containing sulfuric acid and ammonia. The molecular Rayleigh, and hyper-Rayleigh, scattering intensities were expressed from the total dipole polarisability a and hyperpolarisability b tensors allowing for the exploration of the effect of cluster morphology on the scattering properties.…”

A combined ab initio and Franck–Condon simulation study of the photodetachment spectra of the HCBr− anion

“…Recently, the haze weather continues, and this has set the alarm bells ring for human survival [1,2]. Research in the important environment-related molecules are expected to help prevent environmental problems and govern environmental issues, which has been an important research field in molecular physics and chemical physics.…”