Using an alternative technique to trap keV ion beams, the kinetic-energy release after dissociative charge transfer of vibrationally cold ${\mathrm{HeH}}^{+}$ was measured. The results indicate that rapid radiative vibrational cooling takes place during the trapping, thus allowing a direct observation of the $a{}^3{\Sigma }^{+}$ metastable state of ${\mathrm{HeH}}^{+},$ which has been a subject of controversy in previous dissociative recombination experiments.

The lifetime of the metastable ${\mathrm{Be}}^{-}{(2s2p}^2{}^4{P}_{3/2})$ state is measured using an electrostatic linear ion trap which stores keV-ion beams. Trapping using electrostatic fields avoids the complication of magnetic-field-induced mixing effects which can interfere with the measurement of the spontaneous decay. The result is found to be $42.07\pm 0.12\mu \mathrm{s},$ which is a factor of 40 better in accuracy than the previous result determined in a heavy-ion storage ring. The measured lifetime is found to be 30% longer than the most recent theoretical value.

The cross sections for electron detachment of internally cold $\mathrm{C}_n{}^{-}$ and $\mathrm{A}\mathrm{l}_n{}^{-}$ clusters were measured using an electrostatic ion beam trap fitted with an internal electron target. The measured electron-impact detachment cross sections for the $\mathrm{C}_n{}^{-}$ ($n=1–9$) clusters exhibit even-odd oscillations reflecting the binding energy trend, namely, higher cross sections for weaker binding. Surprisingly, however, these cross sections increase on the average with cluster size, $n$, in spite of the increase in electron binding. In contrast, the $\mathrm{A}\mathrm{l}_n{}^{-}$ ($n=2–5$) clusters follow the known scaling laws for electron detachment. We suggest that the size-dependent polarizability of these clusters is responsible for the observed behavior.

Electro-fermentation (EF) is an emerging bioprocess with the ability to regulate the metabolism of electrochemically active microorganisms. In various fermentation processes, electrodes perform either as an electron acceptor or donor, facilitating the formation and movement of electrons and protons. The bioelectric activity created by external electrodes enhances the metabolic reactions, resulting in a higher yield of value-added chemicals. The conventional fermentation process has a number of limitations in terms of usability and economic feasibility, whereas electro-fermentation presents a hybrid technology, minimizing redox instabilities and enhancing the metabolic process in general to achieve increased product production and a higher biomass yield. Electrochemically active microorganisms such as Geobacter and Shewanella species can carry out the exchange of electrons with electrodes directly or indirectly by using electron mediators. Furthermore, the integration of microbial fuel cells (MFCs) with microbial electrolysis cells (MECs) precludes the need for external manipulation of the fermentation system as the required change in electrochemical gradient is provided by the MFC counterpart. The major beneficial aspects of electro-fermentation include its role as a potential tool for enhancing the production of value-added compounds. The mixed-culture system clearly had a favorable impact on the synthesis of butyric acid from rice straw. Furthermore, cathodic electro-fermentation (CEF) exhibited benefits over anaerobic fermentation, influencing NADH/NAD⁺, enabling a higher product titer, and reducing the accumulation of byproducts. Hence, in this review, we emphasize the importance of electro-fermentation over conventional fermentation for biofuel and biochemical production, covering its fundamentals, interactions, types, future challenges, and ability to provide several benefits to boost the fermentation process, such as the process efficiency and product yield, on an industrial scale.