雪宝顶扁平状绿柱石的显微振动光谱研究

Micro-vibrational Spectroscopy of Tabular Beryl from Xuebaoding

四川绵阳雪宝顶绿柱石由于其独特的透明扁平状结构而备受关注,目前其扁平状形成原因还存在分歧。本文应用显微振动光谱及成像,结合化学定量检测,对雪宝顶绿柱石进行了深入分析。显微红外成像表明通道中除了水分子,还存在铁合水离子和二氧化碳分子,且在晶体中不均匀分布。Li元素替换Be元素会造成Be-O四面体和Al-O八面体结构畸变,表现为晶格振动模式的拉曼峰位向高波数偏移。同时,通道中水分子与Na结合,使其极化率减小,表现为伸缩振动模式的拉曼峰位向低波数偏移。本文研究为探究雪宝顶绿柱石扁平状成因提供了基础,为研究单个水分子量子态提供了参考。

The beryl from Xuebaoding,Mianyang,Sichuan,China has attracted much attention because of its unique transparent tabular shape.However,there are still different opinions about the real reason of the tabular shape.In this study,the micro-vibrational spectroscopy combined with quantitative chemical component is used to analyze the Xuebaoding beryl further.The micro-IR mapping shows that there are not only water molecules but also water-Fe3+ ions and carbon dioxides in the channel.They distribute unevenly in the crystal.Element substitution between Li and Be will cause structural distortion of Be-O tetrahedron and Al-O octahedron which can be reflected as the lattice vibrational bands blue-shift in the Raman spectroscopy.Meanwhile,the stretch mode band of water molecule shows red-shift in Raman spectroscopy because of the reduced polarizability caused by combining with Na+ in the channel.This study provides not only a further understanding for exploring the genesis of the tabular habit of Xuebaoding beryl,but also a reference for studying the quantum state of a single water molecule.