本實驗以連續時間光電子能譜技術來研究不同能量的光子照射在吸附於Si(111)-7×7之CF3Br分子的表面光解作用。我們以能量98 eV及120 eV的同步輻射光做為探測光源。由照光後取得的第一個光電子能譜，我們得知CF3Br分子是以分子性物理吸附在Si表面上的。而在連續照光過程中取得的一系列光電子能譜顯示譜線的形狀會隨著光子曝露量的增加而變化。此變化表示吸附的CF3Br分子具有很高的光解截面。至於分子主要的解離機制是被光子激發的來自Si塊材的低動能電子引發的解離性電子附著(Dissociative Electron Attachment)及雙極解離(Dipolar Dissociation)。藉由觀察CF3Br的3a1分子軌道隨光子曝露量增加而變化的情形，我們可以得到分子在不同光子照射下的光解截面。我們得到在98 eV光子照射下之光解截面為3.6×10-18cm2，以及在120 eV光子照射下之光解截面為6.2×10-18cm2。此兩個光解截面的差異是120 eV光子可以游離Si塊材內之Si(2p)蕊層電子，經由歐傑過程所製造的歐傑電子最終將產生較多的低動能電子發射。

The continuous-time photoelectron spectroscopy (PES) was employed to study the photolysis of CF3Br molecules adsorbed on Si(111)-7×7. Evolution of adsorbed CF3Br was monitored at two photon energies of 98 eV and 120 eV. By the first PES spectrum, we know that CF3Br molecules physisorb on Si surface molecularly. The sequential PES spectra show the variation of their shapes with photon exposure. This change indicates that the adsorbed CF3Br molecule has high photolysis cross section. The dissociation of CF3Br is mainly due to dissociative electron attachment and dipolar dissociation induced by photoelectrons. The photoelectrons emitting from the silicon surface are produced by the incident photons. From the variation of the 3a1 obital of CF3Br with photon exposure, we can obtain the photolysis cross section at different photon energies. The photolysis cross sections that we obtained were 3.6×10-18 cm2 at 98 eV photons and 6.2×10-18 cm2 at 120 eV photons, respectively. The difference of these two photolysis cross sections is due to the fact that the 120 eV photons can ionize the Si(2p) core-level of silicon substrate, and the following Auger process will produce Auger electrons resulting in the higher emission of low-energy electrons.

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