Thermal and Nonthermal Effects in Plasmon‐Mediated Electrochemistry at Nanostructured Ag Electrodes

Hot carriers (HCs) and thermal effects, stemming from plasmon decays, are crucial for most plasmonic applications. However, quantifying these two effects remains extremely challenging due to the experimental difficulty in accurately measuring the temperature at reaction sites. Herein, we provide a novel strategy to disentangle HCs from photothermal effects based on the different traits of heat dissipation (long range) and HCs transport (short range), and quantitatively uncover the dominant and potential‐dependent role of photothermal effect by investigating the rapid‐ and slow‐response currents in plasmon‐mediated electrochemistry at nanostructured Ag electrode. Furthermore, the plasmoelectric surface potential is found to contribute to the rapid‐response currents, which is absent in the previous studies.     

N-lines and chromium-pairs in the luminescence spectra of the spinels ZnAl2O4:Cr3+ and MgAl2O4:Cr3+

It is shown that the N-lines in the luminescence spectra of the two spinels ZnAl₂O₄:Cr³⁺ and MgAl₂O₄:Cr³⁺ exhibit quite similar dependencies on chromium concentration, excitation frequency, and thermal treatment of the samples. While most of these lines are structure dependent, the line N₄ at $\text{ν}{}_{\mathrm{R}}\text{?}\text{ν}\text{≈ 400}\text{cm}{}^{\mathrm{?1}}$ and two very weak lines are in both cases due to chromium-pairs. The exchange Hamiltonian H_ex = JS₁ · S₂ + j(S₁ · S₂)² used for the ground-state splitting is fitted by the parameters J = 40.9 cm^?1, j = 1.5 cm^?1 and J = 45.6 cm^?1, j = 2.0 cm^?1 for ZnAl-spinel and MgAl-spinel, respectively. The differences between the spectra of low-doped and high-doped samples are in both cases caused by the existence of a phonon sideband of the N₄-line, which is in many respects similar to the well-known phonon side band of the R-line.