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The nanoparticle density (PD) of the substrates is crucial for surface‐enhanced Raman scattering (SERS) performance. Here, bottom‐up SERS substrates based on rough gold nanorods (R‐Au NRs) with different PD are fabricated and their SERS property are investigated. In particular, R‐Au NRs are deposited on the Si wafer from sparse to dense through electrostatic interaction and from monolayer to multiple layers by interface self‐assembly technique. It is found that the SERS intensity increases dramatically with increasing PD and remains almost unchanged when the PD increases to 241.22 counts µm−2, and the limited penetration depth of laser is the reason for the intensity saturation. Additionally, similar results are observed in the smooth Au NRs substrates, re‐confirming the PD‐dependent SERS performance. Importantly, the SERS activity of R‐Au NRs substrates is higher than smooth Au NRs substrates in each PD, indicating that R‐Au NRs can produce stronger electromagnetic field enhancement, which is supported by the theoretical simulation results. Finally, it is demonstrated that the optimal SERS substrates can be effectively utilized for the quantitative measurement of thiram in soil. Briefly, the PD of substrates has a great impact on SERS activity, which offers an idea for the design of highly efficient SERS substrates. [ABSTRACT FROM AUTHOR]

The FH2– anion has a stable structure that resembles a configuration in the vicinity of the transition state for neutral reaction F + H2 → HF + H. Electron photodetachment spectra of the FH2– anion reveal the neutral reaction dynamics in the critical transition-state region. Accurate quantum dynamics simulations of the photodetachment spectra using highly accurate new ab initio potential energy surfaces for both anionic and neutral FH2 are performed and compared with all available experimental results. The results provide reliable interpretations for the experimental observations of FH2– photoelectron detachment and reveal a detailed picture of the molecular dynamics around the transition state of the F + H2 reaction. The latest high-resolution photoelectron detachment spectra [Kim et al. Science, 2015, 349, 510-513] confirm the high accuracy of our new potential energy surface for describing the resonance-enhanced reactivity of the neutral F + H2 reaction.

Theoretical studies of the dynamics of the abstraction reaction, H' + HBr (v=0,j=0) --> H'H + Br, have been performed with quasiclassical trajectory method (QCT) on a new ab initio potential energy surface (Y. Kurosaki and T. Takayanagi, private communication). The calculated QCT cross sections are in good agreement with earlier quantum wave packet results over most of the collision energy range from 0.1 to 2.6 eV, and the state-resolved rotational distributions of the product H'H molecule are quantitatively consistent with the experimental results. Comparisons of the QCT-calculated rotational-state-resolved cross sections on different potential energy surfaces show that the characteristics of the potential energy surface in the region far away from the minimum energy path have a large influence on the title abstraction reaction dynamics, and the indirect reactions that do not follow the minimum energy path have little influence on the differential cross sections (DCS). The DCSs are mainly governed by the direct reactions that do follow the minimum energy path, at both low and high collision energies. The degree of the rotational alignment of the product H'H molecule is strong at high collision energies, which means that the influence of the indirect reactions on the product rotational alignment is negligible, whereas the distribution of P(varphi(r)) is sensitive to the indirect reactions at high collision energies. With increasing collision energy, the polarization of the product rotational angular momentum decreases and the molecular rotation of the product prefers an in-plane reaction mechanism rather than the out-of-plane mechanism.