含釕化合物修飾碳管探討：光磁轉換機制 STM/STS 分析

Abstract

有鑒於2,2-二吡啶-5-胺基菲羅啉釕修飾奈米碳管在室溫下具有光磁轉換與光電轉換的應用潛力，本實驗進以STM影像分析術對其表面進行能態分析，探討這些修飾碳管表面受到473 nm雷射光照射時，其電子傳導能態密度分布是否與修飾物組成與大小有關。實驗結果顯示：於光照下，2,2-二吡啶-5-胺基菲繞啉釕修飾物可縮小奈米碳管表面電子傳導能隙 (Energy gap)，因而提升碳管表面上電子的傳導速率。實驗結果也顯示：碳管表面電子傳導能帶間隙與修飾物粒徑大小有關，隨釕修飾物粒徑變大而變大，致使其光電流隨釕修飾物粒徑增大而降低。雖然如此，其光磁性則隨釕修飾物粒徑增大而增大。

Carbon nanotubes (CNTs) show photomagnetism and photoconductivity at room temperature after the modification with bis(2,2-bipyridine)-5-amino-1,10-phenanthroline ruthenium (II) (Ru(bpy)2(phen-NH2)2+) on their surface through diazotization and denitrogenation processes. In view of this, we carry out investigations on the Ru(bpy)2(phen-NH2)2+-modified CNTs regarding the origin of the photoactivity with the STM/STS techniques. The energy gap (Eg) between the conduction band and the valence bands of the host CNTs are functions of power of the incident light and the size of the modifier. The gap decreases with the power of the light, but increases with the size of the modifier as exposed to photo illumination at 473 nm. Nevertheless, the photomagnetism increases in amplitude with the size of the nano modifier.