Ni 6221

TAS measurements were carried out using the third harmonic of a Nd:YAG laser (EKSPLA, NT 342B, 355 nm, 5 ns pulse width, 0.9 Hz) as the excitation source. A liquid light guide transmitted the laser pulse to the sample resulting in an incident pump intensity of ca. 177 μJ cm⁻² (355 nm). A 100 W tungsten lamp (Bentham, IL 1) coupled to a monochromator (Zolix, Omni - λ 300) was used as the probe light. Variation in optical density (∆OD) of the sample was calculated by measuring the transmitted light using a Si photodiode (Hamamatsu) and an amplification system coupled to both an oscilloscope (Tektronix, TDS 2012C) and data acquisition card (National Instruments NI-6221). The data were averaged over 400 laser shots. OCP measurements were conducted in 1 M NaOH solution with or without 0.5 M Na₂SO₃. The operando TAS experiments were implemented by three-electrode setup controlled by a CHI 760C potentiostat in 1M NaOH solution (pH = 13.7), with the photoanode, Pt, and Ag/AgCl as working, counter and reference electrodes, respectively. During TAS measurements, a constant potential was maintained by chronoamperometry.

SCR was measured continuously at 100 Hz using a pair of disposable, pre-gelled 8-mm Ag/AgCl electrodes (Biopac Systems) attached to the palm of the non-dominant hand. The electrodes were connected to an isolated skin conductance coupler (LabLinc v71–23, Coulbourn Instruments). The skin conductance module was further connected to a 16-bit AD converter (National Instruments, NI-6221), which digitized the raw analogue SCR signal. Offline data extraction was completed with PSPHA^{27 (link)}. SCR amplitude was determined by subtracting the average of a 2-s baseline (prior to stimulus onset) from the maximum response in a 0–7 s window following stimulus onset. This is an established approach for calculating SCR and has been extensively used in the past in our lab as well as others^{17 (link),28 (link)–35 (link)}. All responses were kept in the analysis, and SCR data were Z-transformed analogously to FPS responses.

FPS was measured through electromyography (EMG) of the right orbicularis oculi muscle. Two 4-mm Ag/AgCl electrodes filled with conductive electrolyte gel (Microlyte, Coulbourn Instruments, Holliston, Massachusetts) were placed 1 cm below the pupil and 1 cm below the lateral canthus, and a third (ground) electrode was placed on the forehead^{26 (link)}. Acoustic startle probes (40 ms white noise, 100 dBA) were presented binaurally through headphones (Sennheiser HD 202). The EMG signal was sampled at 1000 Hz and amplified using an isolated bioamplifier with band-pass filter (Lablinc v75-04, Coulbourn Instruments) with a high pass filter of 13 Hz and a low pass filter of 500 Hz. The signal was rectified and smoothed online at a time constant of 20 ms, using a 4-channel integrator (Lablinc v76-24, Coulbourn Instruments). The analogue output was then digitized by a 16-bit AD converter (National Instruments, NI-6221, Austin, Texas). Offline processing was completed with PSPHA^{27 (link)}. Blink amplitude was determined by subtracting a 20-ms baseline (0–20 ms following probe onset) from the peak response in a 21–200 ms window following probe onset. To standardize the data, means and standard deviations from the first testing session were used to calculate within-participant Z-scores.