[Mid-infrared and Raman spectral analysis of geometrically frustrated natural atacamite]

At room temperature, the mid-infrared spectra of geometrically frustrated natural atacamite (hydroxyl copper chloride, beta-Cu2(OH)3Cl) in the range of 4 000-400 cm(-1) were measured by FTIR spectrometers, and meanwhile its Raman spectrum in the range of 4 000-95 cm(-1) was obtained by Jobin Yvon LabRAM HR800 Raman spectrometer. According to its crystal structure parameters, the authors confirmed the characteristic peaks of sample 4 000-2 500-1 000 cm(-1) in the functional group region and 1 000-550-200-95 cm(-1) in the fingerprint region, and also explored its microscopic origin Five distinct regions were assigned: the hydroxyl stretching vibration v(O-H) determined by the overall environment around the hydroxyl group; the overtones generated by the sum or multiplication of fundamental frequencies of hydroxyl bending vibration; the hydroxyl bending vibration modes delta(O-H) of the combination of delta(Cu-O-H) and delta(O-H...HCl); the vibration modes of strongly bonded planar CuO4 units; the vibration modes of weakly bonded linear-triatomic chain Cl-Cu-O/Cl. The bands were assigned in accordance with its crystal structure parameters, which is more reasonable to establish the relationship between its molecular structure and its respective spectral properties.