Theta probe

Raman spectra were collected in a spectrograph system (Andor Technology; model: SR-500i-D2-R) with a high-performance laser source (Cobolt Samba^TM; wavelength 532 nm and laser power of 5 mW) and CCD detector (model: DV416A-LDC-DD). The silicon vibration peak located at 520 cm⁻¹ was utilized to calibrate the measurement system. The elemental composition was determined using XPS (Thermo Fisher Scientific Theta Probe, Al Kα X-ray source). The carbon 1 s peak was used to calibrate the reference of binding energy. The measurement was performed in an ultra-high vacuum condition (~10⁻⁹ torr) and with a beam size of 400 μm. For XPS depth profiling, in-situ Ar sputtering was utilized with an etching rate of 0.298 nm per second for the as-sputtered MoTe₂ film. The spectra of binding energy were deconvoluted using the Shirley background correction and characterized based on NIST XPS database^{24 (link)}. The relative sensitivity factors of Mo 3d_5/2, Te 3d_5/2, and O 1 s were 6.51, 25 and 2.88, respectively. The deconvoluted Mo 3d line shape was fit using an asymmetry distribution of LA (1.1, 2.3, 2) while others were fit using a symmetric distribution of Gaussian–Lorentzian (60).

The XPS analysis was performed using a Thermo Fisher Scientific Theta Probe (Thermo Fisher Scientific, Waltham, MA, USA) spectrometer. For analysis, a monochromatic Al Kα (1486.6 eV) X-ray source was used. The spectra were measured at room temperature at a pressure of ~5 × 10⁻⁸ Pa in the analytical chamber. The samples were mounted on a titanium sample holder with two-sided adhesive tape. The energy scale of the spectrometer was calibrated to provide the following values for reference samples (i.e., metal surfaces freshly cleaned by ion bombardment): Au 4f_7/2–83.96 eV, Cu 2p_3/2–932.62 eV, Ag 3d_5/2–368.21 eV. Survey and high-resolution spectra of appropriate core levels were recorded at constant pass energies of 300 and 100 eV and with step sizes of 1 and 0.1 eV, respectively. The electrostatic charging effects were compensated by using an electron neutralizer. The binding energy scales for the cellulose samples were referenced to the C–OH component in the C 1s spectra at 286.73 eV [62 (link)] and for Ag black at 285.0 eV. After charge referencing, a Shirley-type background with inelastic losses was subtracted from the high-resolution spectra. The surface chemical composition was calculated using atomic sensitivity factors included in the software of the spectrometer corrected for the transfer function of the instrument.

The height and width of the resultant GO nanosheets were investigated by atomic force microscopy (AFM; Nanocute, Hitachi High-Tech Sci. Co.). X-ray diffraction (XRD) patterns were collected on a Rigaku SmartLab 3 kW X-ray diffractometer equipped with a Cu Kα (λ = 0.154 nm) radiation source. A field-emission Scanning electron microscopy (FE-SEM) images were recorded on a SU-8000 (Hitachi High-Technologies Corporation) microscope. Elemental analyses and chemical-state profiles were conducted using an X-ray photoelectron spectroscopy (XPS) apparatus (ThetaProbe, Thermo Fisher Scientific). The C 1s XPS spectra were fitted based on of the contributions of eight groups (–COOH, C<svg xmlns="http://www.w3.org/2000/svg" version="1.0" width="13.200000pt" height="16.000000pt" viewBox="0 0 13.200000 16.000000" preserveAspectRatio="xMidYMid meet"><metadata>
Created by potrace 1.16, written by Peter Selinger 2001-2019
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O, C–O–C, C–OH, sp³ C–C, C–H defects, C–N, and sp² CC bonds). Fe 2p_3/2 and Fe 2p_1/2 XPS spectra were fitted based on the contributions from four groups (Fe²⁺ + N, Fe³⁺ + N, Fe oxide, and Fe satellite).

The thickness of the film deposited on the Si substrate was measured using spectroscopic ellipsometry (UVISEL, Horiba, Kyoto, Japan). XPS (Theta Probe, Thermo Fisher Scientific Co., Waltham, MA, USA) was used to analyze the chemical bonding of the HfO_x films and to ascertain the presence or absence of La in the HfO_x films. The morphological properties of the deposited films were characterized by AFM (XE-100, Park Systems, Suwon, Korea). Furthermore, the crystalline phase and crystallite size and orientation were determined by GI-XRD (SmartLab, Rigaku, Tokyo, Japan) and TEM (Tecnai F20 G², FEI, Hillsboro, OR, USA). For the cross-sectional TEM image, a sample was prepared using the focused ion beam system, and for the plan view TEM image, samples were prepared using the ion milling system.

X-ray photoelectron spectroscopy (XPS), electron spectroscopy for chemical analysis, was used for determining the functionalization of the NW surface [29 (link)]. XPS measurement was performed using a Thermo Fisher Scientific Theta Probe with a monochromatic X-ray source (Al Kα, 1486.6 eV) and a concentric hemispherical analyzer. Binding energy of 284.6 eV for the C 1s peak was calibrated as the reference. XPS analysis was performed by National Nano Device Laboratories (Hsinchu, Taiwan).