Nicolet nexus 470 spectrometer

Transmission electron microscopy (TEM, JEOL, Tokyo, Japan) and high-resolution TEM (HRTEM) images were taken on a JEOL-2100F transmission electron microscope. Scanning electron microscopy (SEM, JEOL, Tokyo, Japan) images, energy dispersion spectrum (EDS), and elemental mapping images of the samples were taken on a JSM-4800F scanning electron microscope. Atomic force microscopy (AFM, Bruker, Billerica, MA, USA) images were measured on a Bruker Multimode 8 AFM system. X-ray diffraction (XRD, Rigaku Corporation, Tokyo, Japan) patterns of g-C₃N₄, EF, and as-prepared EFC heterojunctions were taken on a Rigaku Smartlab diffractometer. Fourier-transform infrared spectra (FTIR, ThermoFisher, Waltham Mass, MA, USA) were recorded on a Nicolet NEXUS 470 spectrometer in the range of 4000–400 cm⁻¹. XPS spectra (ThermoFisher, Waltham, MA, USA) were detected on a Thermo ESCALAB 250XI X-ray photoelectron spectroscopy spectrometer equipped with anAlKαX-ray source. The N₂ adsorption desorption isotherms and BET specific surface area was measured on a Micromeritics ASAP 2460 analyzer at 77 K (Micrometrics, Londonderry, NH, USA).

FTIR and NMR assays were carried out according to previous methods [80 (link),81 (link)]. For FTIR spectra, KSC and its oligosaccharides (2.0 mg) were mixed with KBr (200 mg) powder, ground and pressed, and then measured on a Nicolet Nexus 470 spectrometer (Thermo Fisher Scientific, Waltham, MA, USA). For NMR spectra, KSC (50 mg) was dissolved in 500 μL 99% of the D₂O, freeze-dried and repeated 3 times. The sample was then redissolved in 500 μL D₂O and transferred to an NMR tube. Finally, ¹H-NMR/¹³C-NMR with Agilent DD₂ 500 MHz NMR spectrometer was performed with acetone as the internal standard.

The freeze-dried samples were ground into small fragments. After that, the PSAH, PGAH, and PAAH were analyzed in KBr (potassium bromide) disks by Fourier transform infrared spectroscopy (Nicolet Nexus 470 spectrometer, Thermo Scientific, Waltham, MA, USA). The wavenumber range scanned was 4000–500 cm⁻¹; 32 scans of 2 cm⁻¹ resolution were signal-averaged and stored. The films utilized in this analysis were sufficiently thin to obey the Beer–Lambert law.

¹H NMR and ¹³C NMR spectra were performed at 25 °C on an Agilent DD2 500M NMR spectrometer (Agilent Technologies, Santa Clara, CA, USA). Polysaccharide (60 mg) was deuterium-exchanged by lyophilization three times with 99.9% D₂O and then was dissolved in 0.5 mL of 99.9% D₂O and transferred into NMR tube. Chemical shift was expressed as δ (ppm) relative to acetone (¹H: 2.225 ppm, ¹³C: 31.07 ppm). ¹H–¹H COSY, ¹H–¹H TOCSY, ¹H–¹³C HSQC, ¹H–¹H NOESY and ¹H–¹³C HMBC experiments were also carried out. Spectra were processed and analyzed using MestReNova (V12.0.3, Mestrelab Research, Santiago de Compostela, Spain). For the FTIR spectrum, the polysaccharide was ground with KBr, pressed into a 1 mm transparent sheet and then determined on a Nicolet Nexus 470 spectrometer (Thermo Fisher Scientific, Waltham, MA, USA) with a scan range of 400–4000 cm⁻¹. UV spectrum was recorded on a UV-2802 PC spectrophotometer (UNICO Shanghai Instrument Co., Ltd., Shanghai, China) between 190 and 400 nm.

The obtained PbSe films were characterized structurally by X-ray diffraction (XRD), using a PANalytical XPERT-PRO diffractometer with Cu-Kα emission line, in the scan range of from 20° to 80° and a step 0.04°. Optical characterization was performed by spectral absorption measurements, using a JASCO V-670 spectrophotometer in the 400–1800 nm wavelength range with a resolution of 1.0 nm and by FTIR with a Thermo Nicolet Nexus 470 spectrometer in absorption mode and scan resolution of 2.0 cm⁻¹. For FTIR characterization, PbSe powders and KBr were mixed to produce a pellet with a ratio of 1/50, PbSe/KBr W/W. Also, the powder and films were characterized morphologically by scanning electron microscopy (SEM), where a FE-SEM Zeiss Auriga 39–16 operating at between 1 and 2 kV was used.

Attenuated Total Reflection (ATR)-FTIR type spectra were obtained using a Nicolet NEXUS 470 spectrometer (Thermo, Waltham, MA, USA). The spectrum scope of samples was taken between 4000 cm⁻¹ and 650 cm⁻¹.