Phi multipak software

X-ray photoelectron spectroscopy (XPS) was performed with a photoelectron spectroscopy system (PHI 5000 Versa Probe II, ULVAC-PHI). Monochromated Al Kα (1486.6 eV) radiation with an operating power of 50 W (15 kV voltage) was used in all the XPS measurements. The analyzed area was 200 μm. The XPS survey spectra (Figure 3B) were measured with a pass energy of 117.4 and 0.125 eV energy step. For the measurement of each atomic element, pass energy of 23.5 and 0.025 eV energy steps were used. The recorded signals were accumulated eight times for C1s, O1s, and twelve times for other elements. A take-off angle was 45° to the sample substrate. During the measurement, the samples were neutralized using both a low-energy ion beam and a low-energy electron beam.
For data analysis, we used PHI MultiPak software (ULVAC-PHI). The signal background of each component was subtracted using the Shirley method. The atomic concentration was calculated by considering the relative sensitivity factor for each element corrected with the sensitivity factor of the system. The fitting protocol used the Gaussian-Lorentzian function, but the best fit results were obtained with Gaussian 100%.

The collected solid samples were analyzed using X-ray photoelectron spectroscopy (XPS) to obtain chemical characterization of the aerosols. For the XPS measurements a Perkin Elmer Phi 5500 multi technique system was used. The detailed setup of the machine during measurements was described in a previous work [20 (link)]. Commonly, the C 1s peak originating from the unavoidable atmospheric contamination is used as an internal standard for the binding energies (BEs) during XPS measurements. In the case of ruthenium the Ru 3d_5/2 peak and the C 1s peak are overlapping, making this reference unreliable. To avoid this problem the gold foil conductively connected to the measured samples was used as an internal standard during the measurements. The experimental uncertainty of BE of the Ru 3d_5/2 peak was determined to be ±0.1 eV. The curve fitting of the obtained spectra was made using PHI Multipak software (Ulvac-Phi, Inc.), assuming Shirley background. The asymmetrical shape of peaks was used due to the conductive nature of anhydrous RuO₂ [21 (link)]. XPS analysis was performed using at least two different spots on the samples.

The morphology of the TNB was observed with field-emission scanning electron microscope (SEM, JSM-7600 F, JEOL Ltd., Japan). The crystal structure of samples was identified by PANalytical X-ray diffractometer (XRD, PANanalytical, Westborough, MA). The chemical structure of surface-modified TiO₂ was analyzed by X-ray photoelectron spectra (XPS)(PHI 5000 Versa Probe system Physical Electronics, Chanhassen, MN); and the deconvolution of XPS peak was carried out using the PHI Multipak™ software with the Gauss-Lorentz line and Shirley background subtraction (Physical Electronics, Chanhassen, MN). The monolayer on the TNP was further characterized by Fourier transform infrared spectra (FTIR), and measured under the transmission mode with a Thermo Nicolet 6700 spectrometer (ThermoFisher, Houston, TX). The zeta potential and aggregate size of the ENM was measured using electrophoretic light scattering with a Malvern Zetasizer Nano-ZS instrument (Malvern Instruments Ltd., Worcestershire, UK). The Malvern software established a number of pseudo-replicate runs (usually 10 to 20) to establish one value and these were repeated 3 times for an average value. The standard deviations of these data were always less than 10% of the means, and most were less than 5% indicating very little variance in the replications.