Approach to thermal equilibrium in atomic collisions.
Approach to thermal equilibrium in atomic collisions.
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DOI：
10.1142/9781848164703_0018
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发表时间：
2008-03
影响因子：
8.6
通讯作者：
Peng Zhang;V. Kharchenko;A. Dalgarno;Y. Matsumi;T. Nakayama;Kenshi Takahashi
中科院分区：
文献类型：
--
作者：
Peng Zhang;V. Kharchenko;A. Dalgarno;Y. Matsumi;T. Nakayama;Kenshi Takahashi
从实验和理论上探讨了快原子在热浴气体中运动的能量弛豫。两个时间尺度表征的平衡，一个短的时间，其中各向同性的能量分布曲线放松到麦克斯韦形状在一些中间的有效温度，和第二，一个较长的时间，其中的松弛保持麦克斯韦分布和其有效温度连续下降到浴气体温度。麦克斯韦分布的形成和保持不依赖于射弹与浴气体原子的质量比。这种两阶段行为是由于中性粒子碰撞中小角度散射和小能量转移的主导作用而产生的。从激发的初始能量氮原子穿越浴气体的氦和氩的发射的不断发展的多普勒配置文件的测量证实了理论预测。
The energy relaxation of fast atoms moving in a thermal bath gas is explored experimentally and theoretically. Two time scales characterize the equilibration, one a short time, in which the isotropic energy distribution profile relaxes to a Maxwellian shape at some intermediate effective temperature, and the second, a longer time in which the relaxation preserves a Maxwellian distribution and its effective temperature decreases continuously to the bath gas temperature. The formation and preservation of a Maxwellian distribution does not depend on the projectile to bath gas atom mass ratio. This two-stage behavior arises due to the dominance of small angle scattering and small energy transfer in the collisions of neutral particles. Measurements of the evolving Doppler profiles of emission from excited initially energetic nitrogen atoms traversing bath gases of helium and argon confirm the theoretical predictions.