Study on Dynamic Processes of Adsorption and Desorption by means of Time-Resolved Reflectance Spectroscopy

利用实时多通道反射光谱技术研究了气体在固体表面吸附和解吸的动态过程，其中吸附状态由光谱结构指定。(1)在W（001）表面吸附氮气时，发现3.8 eV和2.1 eV下的光谱结构分别与beta_2和beta_1态相关。β _1态的发展首先通过2.1eV的结构增强实现。氮的渗透可能解释了这种状态(2)。室温下Si（111）对氯的吸附新发现如下。1)发现主要过程是原子的吸附而不迁移。确定悬垂键的初始粘附概率为0.48，背键的初始断裂概率为0.14。2)高掺杂硅的初始断裂概率和断裂回键总数更大。孔可能会削弱后面的键。3)在3.6eV左右，SiCI的体态到反键态之间存在由光学跃迁引起的结构。(3)氯饱和Si（111）表面在740K下退火，形成了覆盖* SiCI的静止原子表面。在880 ~ 940k下，剩余原子表面氯的解吸有如下新发现。1)发现主要工艺是修复回粘。测定的活化能为2.7 eV，对应于反应的势阱能，SiCl +SiCl *** SiCI_2 + Si.2)悬空键的恢复仅在解吸的初始阶段观察到。研究表明，根据反射光谱结构确定化学键可以实时研究吸附和解吸的动态过程。

Dynamic processes of adsorption and desorption of gases on solid state surfaces have been studied by real-time multichannel reflectance spectroscopy, in which adsorption states are specified from spectral structures.(1) In the case of nitrogen adsorption on W(001) surface, spectral structures at 3.8 and 2.1 eV are found to be correlated with the beta_2 and beta_1 states, respectively. Development of the beta_1 state is firstly obtained by the enhancement of the structure at 2.1eV.Penetration of nitrogens into the bulk is a possible explanation for this state(2) New findings about chlorine adsorption on Si(111) at room temperature are as follows.1) Main process is found to be adsorption of atoms without migration. Initial sticking probability to dangling bonds and initial breaking probability of back bonds are determined as 0.48 and 0.14, respectively.2) The initial breaking probability and the total number of the broken back bonds are larger for heavyly doped silicon. Holes probably weaken the back bonds.3) A structure originating from optical transitions between the bulk states to the antibonding states of SiCI is found aroud 3.6eV.(3) A rest-atom surface covered with * SiCI is formed by annealing the chlorine-saturated Si(111) surface at 740K.New findings about chlorine desorption from the rest-atom surface at 880-940K are as follows.1) Main process is found to be restoration of back bonds. Activation energy is determined as 2.7 eV and this corresponds to the barrier energy for the reaction, SiCl +SiCl *** SiCI_2 + Si.2) Restoration of dangling bonds are observed only at the initial stage of the desorption.It has been shown that dynamic processes of adsorption and desorption can be real-time studied by specifying chemical bonds from the structures of reflectance spectra.