We investigated interlayer phonon modes of mechanically exfoliated few-layer 2H-SnS2 samples by using room temperature low-frequency micro-Raman spectroscopy. Raman measurements were performed using laser wavelengths of 441.6, 514.4, 532 and 632.8 nm with power below 100 μW and inside a vacuum chamber to avoid photo-oxidation. The intralayer Eg and A1g modes are observed at ~206 cm−1 and 314 cm−1, respectively, but the Eg mode is much weaker for all excitation energies. The A1g mode exhibits strong resonant enhancement for the 532 nm (2.33 eV) laser. In the low-frequency region, interlayer vibrational modes of shear and breathing modes are observed. These modes show characteristic dependence on the number of layers. The strengths of the interlayer interactions are estimated by fitting the interlayer mode frequencies using the linear chain model and are found to be 1.64 × 1019 N · m−3 and 5.03 × 1019 N · m−3 for the shear and breathing modes, respectively.

The evolution of the optical phonons in layered semiconductor alloys SnSe(1-x)Sx is studied as a function of the composition by using polarized Raman spectroscopy with six different excitation wavelengths (784.8, 632.8, 532, 514.5, 488, and 441.6 nm). The polarization dependences of the phonon modes are compared with transmission electron diffraction measurements to determine the crystallographic orientation of the samples. Some of the Raman modes show significant variation in their polarization behavior depending on the excitation wavelengths. It is established that the maximum intensity direction of the Ag 2 mode of SnSe(1-x)Sx (0x1) does not depend on the excitation wavelength and corresponds to the armchair direction. It is additionally found that the lower-frequency Raman modes of Ag 1 , Ag 2 and B3g 1 in the alloys show the typical one-mode behavior of optical phonons, whereas the higher-frequency modes of B3g 2 , Ag 3 and Ag 4 show two-mode behavior.

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The present study aimed to assess the health risks of chemical contaminants of residents in the coastal areas of Cambodia through their drinking water pathways. Water was sampled from tube wells (n= 22), dug wells (n= 31), ponds (n= 11), canals (n= 12) and lakes (n= 4) across the Cambodian coastal areas, and measured for the contaminants of health concern (As, Cu, Cr, Cd, F−, NO2-, NO3-, Pb, Escherichia coli and total coliform) and aesthetic quality following the United States Environmental Protection Agency (USEPA) and standard methods. Analytical results reveal that 9.1% of tube wells and 9.7% of dug wells contained As > 0.01 mg/L. Appropriately, 22.7% of tube wells and 32.3% of dug wells contained Fe > 0.3 mg/L while 100% of tube wells and 80.6% of dug wells contained Mn > 0.1 mg/L. Health risk assessment found that the hazard quotient (HQ) > 1 for children and women. Additionally, the lifetime cancer risk (LCR) was found >1 × 10−4 for As in Cambodian coastal areas. Therefore, a monitoring programme and appropriate treatment to remove contaminants like arsenic, cadmium and fluoride would be required to ensure a safe drinking water supply to Cambodian coastal residents.