单壁碳纳米管的三声子倒逆过程

Three-phonon Umklapp Process in Single-walled Carbon Nanotubes

介绍了单壁碳纳米管的三声子倒逆过程弛豫率的计算,建立了倒逆过程的选择定则,提出了弛豫率的计算公式以及高温和低温极限下的近似计算公式.在线性色散关系下弛豫率在高温时与频率的平方成正比;在低温极限时弛豫率随温度的倒数是按指数律变化;在高温极限时,弛豫率随温度线性增长.在考虑全部色散关系时,随着散射通道的增加,横波声子的总弛豫率曲线随频率增长时出现大量不连续点,并且光学声子的加入使总弛豫率增长了至少一个数量级.

The calculation of the relaxation rate of the three-phonon umklapp process in single-walled carbon nanotubes is introduced.Selection rules are determined for the umklapp process.The equations are developed to get the relaxation rate,and the high and low temperature limit approximations.The rate varies linearly with the square of the frequency under the linear phonon dispersion assumption.The rate varies exponentially with the inverse of temperature in the low temperature limit,and linearly with temperature ...