School of Chemistry, Physics and Mechanical Engineering, Science and Engineering, Faculty Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia.
Spectrochim Acta A Mol Biomol Spectrosc. 2013 Feb 15;103:431-4. doi: 10.1016/j.saa.2012.07.057. Epub 2012 Aug 3.
Plumbogummite PbAl(3)(PO(4))(2)(OH,H(2)O)(6) is a mineral of environmental significance and is a member of the alunite-jarosite supergroup. The molecular structure of the mineral has been investigated by Raman spectroscopy. The spectra of different plumbogummite specimens differ although there are many common features. The Raman spectra prove the spectral profile consisting of overlapping bands and shoulders. Raman bands and shoulders observed at 971, 980, 1002 and 1023 cm(-1) (China sample) and 913, 981, 996 and 1026 cm(-1) (Czech sample) are assigned to the ν(1) symmetric stretching modes of the (PO(4))(3-), at 1002 and 1023 cm(-1) (China) and 996 and 1026 cm(-1) to the ν(1) symmetric stretching vibrations of the (O(3)POH)(2-) units, and those at 1057, 1106 and 1182 (China) and at 1102, 1104 and 1179 cm(-1) (Czech) to the ν(3) (PO(4))(3-) and ν(3) (PO(3)) antisymmetric stretching vibrations. Raman bands and shoulders at 634, 613 and 579 cm(-1) (China) and 611 and 596 cm(-1) (Czech) are attributed to the ν(4) (δ) (PO(4))(3-) bending vibrations and those at 507, 494 and 464 cm(-1) (China) and 505 and 464 cm(-1) (Czech) to the ν(2) (δ) (PO(4))(3-) bending vibrations. The Raman spectrum of the OH stretching region is complex. Raman bands and shoulders are identified at 2824, 3121, 3249, 3372, 3479 and 3602 cm(-1) for plumbogummite from China, and at 3077, 3227, 3362, 3480, 3518 and 3601 cm(-1) for the Czech Republic sample. These bands are assigned to the ν OH stretching modes of water molecules and hydrogen ions. Approximate O-H⋯O hydrogen bond lengths inferred from the Raman spectra vary in the range >3.2-2.62Å (China) and >3.2-2.67Å (Czech). The minority presence of some carbonate ions in the plumbogummite (China sample) is connected with distinctive intensity increasing of the Raman band at 1106 cm(-1), in which may participate the ν(1) (CO(3))(2-) symmetric stretching vibration overlapped with phosphate stretching vibrations.
铅矾 PbAl(3)(PO(4))(2)(OH,H(2)O)(6) 是一种具有环境意义的矿物，属于明矾-铁矾超族的一员。矿物的分子结构已通过拉曼光谱进行了研究。尽管存在许多共同特征，但不同的铅矾标本的拉曼光谱却有所不同。拉曼光谱证明了由重叠带和肩组成的光谱轮廓。在中国样本中观察到的 971、980、1002 和 1023 cm(-1) 和在捷克样本中观察到的 913、981、996 和 1026 cm(-1) 的拉曼带和肩归因于 (PO(4))(3-)的 ν(1)对称伸缩模式，在 1002 和 1023 cm(-1)（中国）和 996 和 1026 cm(-1) 归因于 (O(3)POH)(2-)单元的 ν(1)对称伸缩振动，而在 1057、1106 和 1182 cm(-1)（中国）和在 1102、1104 和 1179 cm(-1)（捷克）的拉曼带和肩归因于 ν(3)(PO(4))(3-)和 ν(3)(PO(3)) 反对称伸缩振动。在中国样本中观察到的 634、613 和 579 cm(-1) 和在捷克样本中观察到的 611 和 596 cm(-1) 的拉曼带和肩归因于 ν(4)(δ)(PO(4))(3-)弯曲振动，而在 507、494 和 464 cm(-1)（中国）和 505 和 464 cm(-1)（捷克）的拉曼带和肩归因于 ν(2)(δ)(PO(4))(3-)弯曲振动。OH 伸缩区域的拉曼光谱很复杂。在中国的铅矾中，拉曼带和肩分别在 2824、3121、3249、3372、3479 和 3602 cm(-1) 处被识别，在捷克共和国的样本中在 3077、3227、3362、3480、3518 和 3601 cm(-1) 处被识别。这些带被分配给水分子和氢离子的 ν OH 伸缩模式。从拉曼光谱推断的近似 O-H⋯O 氢键长度在 >3.2-2.62Å（中国）和 >3.2-2.67Å（捷克）之间变化。在中国样本中少量存在的一些碳酸根离子与拉曼光谱中 1106 cm(-1) 处强度增加有关，其中可能涉及与磷酸伸缩振动重叠的 ν(1)(CO(3))(2-)对称伸缩振动。
