光诱导雄黄矿物同质异象变化的显微成像拉曼散射研究

利用拉曼光谱研究了激光照射诱导雄黄的同质异象变化，这些结果证实了下面的反应：由于As—As键相对较弱，首先As—As键被破坏，有1个S原子加入到As—As键中，形成As—S—As键。此时由As₄S₄(Realgar类型)变化为As₄S₅相，而As₄S₅处于不稳定状态，As₄S₅相变化为 Pararealgar时有1个S原子从As—S—As键中释放出来。释放出来的S原子又加入到另外1个As₄S₄(Realgar)中，引起As₄S₄(Realgar)相变化为As₄S₅,As₄S₅进而分裂为1个S原子和As₄S₄(Pararealgar类型)。照射促进雄黄经由 As₄S₅ 分子被转换成副雄黄。

Microscopic Raman Imaging Spectra of Realgar and Light-Induced Degradation Products in Realgar

Light-induced degradation in realgar was studied by means of Raman spectroscopy. The result substantiated the following reaction: An additional S atom is inserted between the As atoms in the As4S4 molecule because As--As bonds are weaker than As--S bonds. It is likely that the resulting As--S--As molecule is too unstable to exist. Furthermore, an S atom in the As4S5 molecule is released from one of the equivalent As--S--As linkages in As4Ss which becomes the As4S4 molecular of pararealgar. After the As4S5 molecule is divided into an S atom (radical) and the As4S4 (pararealgar type) molecule, the free S atom is re-attached to another As4S4 (realgar type) molecule, reproducing an As4S5 molecule. The reproduced As4S5 molecule is again divided into an S atom (radical) and an As4S4 (pararealgar type) molecule. This cycle whereby realgar is indirectly transformed into pararealgar via the As4S5 molecule is promoted by light and repeated during light exposure.