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   https://doi.org/10.1021/acs.jpca.3c01264  

   Harrilal, Christopher P.; Garimella, Sandilya V.B; Chun, Jaehun; Devanathan, Nikhil; Zheng, Xueyun; Ibrahim, Yehia M; Larriba-Andaluz, Carlos; Schenter, Gregory; Smith, Richard D. (June 2023, The Journal of Physical Chemistry A)
2. Study of ion charging effect to improve reactive-ion-etching profile of PbSe grating structures

   https://doi.org/10.1016/j.mee.2024.112170  

   Hemati, Tehere; Yang, Gang; Weng, Binbin (June 2024, Microelectronic Engineering)

   This research studies the impact of the charging effect on the RIE-etched profile of narrow-slot Lead- Selenide (PbSe) gratings. By decreasing the slot width from 4 to 2 𝜇𝑚, we observed the increased irregularity and RIE-lag in etched profiles.We suggest that the charging effect is the main responsible mechanism for this phenomenon. The accumulated charge on the non-conductive photoresist plays a crucial role in forming this effect. Therefore, introducing a conductive layer can neutralize the accumulated charge and significantly improves the profile. To prove this theory, we introduced a thin layer of copper on the gratings. While without any conductive coating, we failed to etch gratings with a slot width of less than 1 𝜇𝑚, by introducing a copper layer, we succeeded etching gratings with 0.7 𝜇𝑚 slot width with the improved sidewall profiles. Hence, this technique enables us to fabricate sub-micron PbSe gratings with applications of mid-infrared (MIR) devices. 

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3. Connecting the Ion Separation Factor to the Sorption and Diffusion Selectivity of Ion Exchange Membranes

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   Luo, Hongxi; Agata, Wendy-Angela Saringi; Geise, Geoffrey M. (August 2020, Industrial & Engineering Chemistry Research)

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4. Partition energy in polyamide membranes and its link to ion-ion selectivity

   https://doi.org/10.1016/j.memlet.2025.100099  

   Birnhack, Liat; Porat, Oren Ben; Fridman, Ori; Tong, Tiezheng; Epsztein, Razi (June 2025, Journal of Membrane Science Letters)

   Understanding the mechanisms of molecular transport in polyamide membranes is imperative to improve their solute-specific selectivity. We explored the partitioning behaviors of water and salts in polyamide membranes to elucidate the role of ion-membrane interactions in the transport. Quartz crystal microbalance (QCM) was employed to quantify the mass uptake at different temperatures and determine partition energies (Ek) for water and salts under two different pH values. Zeta potential and permeability tests were conducted to support the ionmembrane affinity trends observed with QCM and link these trends to ion-ion selectivity. Our results demonstrate a high affinity of water to the polyamide membrane (Ek < 0), with a significant swelling effect attributed to dipole interactions and hydrogen bonding. Ion partitioning revealed distinct differences between monovalent and divalent cations, as well as between kosmotropic and chaotropic anions. Specifically, divalent cations (Ca2+ and Mg2+) exhibited considerably lower partition energies (-0.99 and 0.29 kcal mol-1, respectively) and more efficient charge neutralization, indicating stronger interactions with the membrane compared to monovalent cations (~2.2 kcal mol-1). The partition energies of the chaotropic iodide and kosmotropic sulphate anions were substantially different (-5.5 and 4.0 kcal mol-1, respectively), likely due to the different tendency of these anions to shed their hydration shell and stick to the polymer. Last, our permeability tests indicate the potential existence of an intrinsic tradeoff between ion partitioning and intrapore diffusion, presumably due to the opposite effects that ion-membrane interactions have on these transport steps. Overall, our work underscores the role of ionspecific interactions in membrane transport and selectivity. 

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   https://doi.org/10.1021/acs.est.5c04303  

   Ershov, Alexander; Xu, Hengyu; Li, Ying; Tong, Tiezheng; Epsztein, Razi (August 2025, Environmental Science & Technology)