Raman spectroscopy of basic copper(II) and some complex copper(II) sulfate minerals: Implications for hydrogen bonding

The minerals used in this study were, Langite (sample D4379, Cornwall, U.K.), Brochantite (samples D20320 Chuquicamata, Chile and D28957 Bisbee, Arizona, U.S.A.), Antlerite (M33489 Antlerite, Chuquicamata, Chile), Posnjakite (M27302 Drakewalls adit, near Gunnislake, Cornwall, U.K.), Cyanotrichite (G14601 Maid of Sunshine Mine, Cochise County, Arizona, U.S.A.), Devilline (G17182 Spania Dolina, Czechoslovakia), Ktenasite (G24983 Glomsevo Kollen, Amot Modum, Norway), Serpierite (G4034 Laurium, Greece), Glaucocerinite (G17641 Maid of Sunshine Mine, Cochise County, Arizona, U.S.A.). The identity of each phase was confirmed using x-ray diffraction, and the compositions checked using EDX measurements. The crystals of the minerals were placed and oriented on a polished metal surface on the stage of an Olympus BHSM microscope, which is equipped with 10× and 50× objectives. The crystals were oriented to provide maximum intensity. All crystal orientations were used to obtain the spectra. Power at the sample was measured as 1 mW. The incident radiation was scrambled to avoid polarization effects. The microscope is part of a Renishaw 1000 Raman microscope system, which also includes a monochromator, a filter system, and a Charge Coupled Device (CCD). Raman spectra were excited by a Spectra-Physics model 127 He-Ne laser (633 nm) at a nominal resolution of 4 cm−1 in the range between 100 and 4000 cm−1. Repeated acquisitions using the highest magnification were accumulated to improve the signal to noise ratio in the spectra. Spectra were calibrated using the 520.5 cm−1 line of a silicon wafer. Spectroscopic manipulation such as baseline adjustment, smoothing and normalization were performed using the Spectracalc software package GRAMS (Galactic Industries Corporation, NH, USA). Band component analysis was undertaken using the Jandel “Peakfit” software package, which enabled the type of fitting function to be selected and allows specific parameters to be fixed or varied accordingly. Band fitting was done using a Gauss-Lorentz cross-product function with the minimum number of component bands used for the fitting process. The Gauss-Lorentz ratio was maintained at values greater than 0.7, and fitting was undertaken until reproducible results were obtained with squared correlations, r2, greater than 0.995.

Figure 1 shows Raman spectrum of the hydroxyl-stretching region of (a) antlerite, (b) brochiantite, (c) posnjakite, (d) langite, and (e) wroewolfeite. Figure 2 shows Raman spectrum of the hydroxyl-stretching region of (a) cyanotrichite, (b) devilline, (c) glaucocerinite, (d) serpierite, and (e) ktenasite. Figure 3 shows Raman spectrum of the hydroxyl-stretching region of (a) cyanotrichite, (b) devilline, (c) glaucocerinite, (d) serpierite, and (e) ktenasite. Figure 4 is the hydrogen-bond distance as a function of the peak position of the symmetric SO4-stretching vibration. Figure 5 shows Raman spectrum of the SO4 bending region of (a) antlerite, (b) brochiantite, (c) posnjakite, (d) langite, and (e) wroewolfeite. Figure 6 shows Raman spectrum of the low wavenumber region of (a) cyanotrichite, (b) devilline, (c) glaucocerinite, (d) serpierite, and (e) ktenasite.

本研究中采用的矿物包括：兰锑石（样本D4379，英国康沃尔），勃朗特石（样本D20320，智利丘基卡马塔和D28957，美国亚利桑那州比斯比），鹿角石（样本M33489，智利丘基卡马塔），波什纳克石（样本M27302，英国康沃尔格尼恩斯莱克附近的Drakewalls竖井），青钴石（样本G14601，美国亚利桑那州科奇斯县阳光矿），迪维林（样本G17182，捷克斯洛伐克斯帕尼亚多利纳），克滕纳石（样本G24983，挪威阿莫特莫杜姆的Glomsevo Kollen），赛皮埃里特（样本G4034，希腊劳里乌姆），蓝铜辉石（样本G17641，美国亚利桑那州科奇斯县阳光矿）。各相的身份均通过X射线衍射进行确认，其成分则通过能量色散X射线（EDX）测量进行核实。矿物晶体被放置并定向于置于奥林巴斯BHSM显微镜载物台上的抛光金属表面，该显微镜配备有10倍和50倍物镜。晶体的定向旨在提供最大强度。所有晶体取向均用于获取光谱。样品上的功率测量为1毫瓦。入射辐射被随机化以避免极化效应。该显微镜是雷尼绍1000拉曼显微镜系统的一部分，该系统还包括单色仪、滤光系统以及电荷耦合器件（CCD）。拉曼光谱由光谱物理公司生产的型号为127的氦-氖激光器（633纳米）激发，在100至4000厘米^-1范围内以4厘米^-1的标称分辨率进行激发。使用最高放大倍数进行重复采集，以改善光谱的信噪比。光谱使用硅片520.5厘米^-1的线条进行校准。使用Spectracalc软件包GRAMS（Galactic Industries Corporation，新罕布什尔州，美国）进行了光谱操作，如基线调整、平滑和归一化。带成分分析采用Jandel "Peakfit"软件包进行，该软件包允许选择拟合函数类型，并允许相应地固定或调整特定参数。使用高斯-洛伦兹乘积函数进行带拟合，拟合过程中使用的成分带数量最少。高斯-洛伦兹比维持在大于0.7的值，拟合一直进行到获得可重复的结果，平方相关系数r^2大于0.995。

图1展示了（a）鹿角石、（b）勃朗特石、（c）波什纳克石、（d）兰锑石和（e）wroewolfeite的羟基伸缩区域的拉曼光谱。图2展示了（a）青钴石、（b）迪维林、（c）蓝铜辉石、（d）赛皮埃里特和（e）克滕纳石的羟基伸缩区域的拉曼光谱。图3展示了（a）青钴石、（b）迪维林、（c）蓝铜辉石、（d）赛皮埃里特和（e）克滕纳石的羟基伸缩区域的拉曼光谱。图4显示了对称SO4伸缩振动的峰位与氢键距离的关系。图5展示了（a）鹿角石、（b）勃朗特石、（c）波什纳克石、（d）兰锑石和（e）wroewolfeite的SO4弯曲区域的拉曼光谱。图6展示了（a）青钴石、（b）迪维林、（c）蓝铜辉石、（d）赛皮埃里特和（e）克滕纳石的低波数区域的拉曼光谱。