Farhat H, Sasaki K, Kalbac M, Hofmann M, Saito R, Dresselhaus M S, Kong J
Department of Materials Science and Engineering, MIT, Cambridge Massachusetts 02139, USA.
Phys Rev Lett. 2009 Mar 27;102(12):126804. doi: 10.1103/PhysRevLett.102.126804. Epub 2009 Mar 25.
The softening of the radial breathing mode (RBM) of metallic single walled carbon nanotubes (m-SWNTs) due to electron-phonon coupling has been studied by observing the Fermi level [see text] dependence of the RBM Raman peak. In situ Raman spectra were obtained from several individual m-SWNTs while varying [see text] electrochemically. The RBM frequency of an intrinsic m-SWNT is shown to be down-shifted relative to highly doped tubes by approximately 2 cm(1). The down-shift is greatest for small diameter and small chiral angle SWNTs. Most tubes show no change in RBM linewidth. A comparison is drawn between the RBM and the G band (A(LO) phonon) with respect to the [see text] dependence of their frequencies and linewidths.
通过观察拉曼峰的费米能级依赖性,研究了由于电子 - 声子耦合导致的金属单壁碳纳米管(m - SWNTs)径向呼吸模式(RBM)的软化。在电化学改变[见正文]的同时,从几个单独的m - SWNTs获得了原位拉曼光谱。相对于高掺杂管,本征m - SWNT的RBM频率显示出大约2 cm⁻¹的下移。对于小直径和小手性角的SWNTs,下移最大。大多数管子的RBM线宽没有变化。就其频率和线宽的[见正文]依赖性而言,对RBM和G带(A(LO)声子)进行了比较。