Phonon-like and single-particle dynamics in liquid lithium
Phonon-like and single-particle dynamics in liquid lithium
复制标题
液态锂中的类声子和单粒子动力学
DOI：
10.1209/epl/i2000-00253-5
复制
发表时间：
1999
期刊：
影响因子：
1.8
通讯作者：
R. Verbeni
中科院分区：
文献类型：
--
作者：
T. Scopigno;U. Balucani;A. Cunsolo;C. Masciovecchio;G. Ruocco;F. Sette;R. Verbeni
利用扩展动量传递区（Q = 1.4 ~ 110 nm−1）的非弹性x射线散射（IXS）重新测量了液态锂（T = 475 K）的动态结构因子S(Q，E)，并提高了能量分辨率（低至1.5 meV）。这些关于这种原型简单液体的新数据允许我们观察到Q从类声子集体模式到单粒子动力学的完整演化。作为Q的函数，我们发现：i)在低Q时，声速的声模为正色散，ii)在中间Q时，激发的能量在晶体布里布鲁因区类似于声子振荡，iii)在高Q时，S（Q，E）接近高斯形状，表明已经达到单粒子动力学。
The dynamic structure factor, S(Q,E), of liquid lithium (T = 475 K) has been remeasured by inelastic X-ray scattering (IXS) in an extended momentum transfer region (Q = 1.4–110 nm−1) and with improved energy resolution (down to 1.5 meV). These new data on such prototypical simple liquid allow to observe the full evolution with Q from a phonon-like collective mode towards the single-particle dynamics. As a function of Q, one finds: i) at low Q's, a sound mode with a positive dispersion of the sound velocity, ii) at intermediate Q's, excitations whose energy oscillates similarly to phonons in the crystal Brillouin zones, and iii) at high Q's, the S(Q,E) approaches a Gaussian shape, indicating that the single-particle dynamics has been reached.