摘要
本實驗室於流動式樣品槽中以266 nm光解碘化甲烷分子 (碘甲烷、二碘甲烷與碘仿)，在初始放射光譜中觀察到電子激發態物種如CH (A2Δ、 B2Σ−、C2Σ+)與C2 (d3Πg)及碘原子 (4P03/2)等，此外，在530 nm~820 nm中觀察到一系列的未知譜帶是光解溴化甲烷分子所沒有觀察到的，經過分析後得知為振動結構。利用同位素取代實驗，將前驅物置換成CD2I2、CD3I與13CH2I2，但在初始放射光譜中並沒有觀察到譜線頻率改變，因此得知此未知物種是只含有碘的分子，並且經由模擬與實驗推測此分子並非碘分子 (B3Π+0,u → X1Σ+g)。將譜線帶入非簡諧振盪模型中計算其振動參數，與文獻對比發現並不是碘分子的雷德堡態 (Rydberg state)、離子對態 (ion- pair)與離子態。分別比較266 nm及532 nm光解碘化甲烷分子的光譜，譜線位置幾乎相同，但強度與波形明顯有不一樣之處。
並列摘要
Nascent emission spectra following the 266 nm photolysis of iodomethanes (CHI3, CH2I2, and CH3I) were recorded in a slow flow system at ambient temperature. We observed the electronically excited species such as CH (A2Δ, B2Σ−, and C2Σ+), C2 (d3Πg), and atomic iodine. Additionally, we found a series of unknown bands that appears at 530-820 nm, and was not seen in the nascent emission spectra following photolysis of bromomethanes. The unknown bands have some distinctive vibrational structures. Nascent emission spectrum following photolysis of the isotopomer (CD2I2, CD3I, or 13CH2I2) was also recorded. No isotopic shifts were observed in nascent emission spectra of unknown bands following the photolysis of CD2I2, CD3I and 13CH2I2. This indicates the carrier probably does not contain hydrogen or carbon atoms. Vibrational analysis shows that the carrier could not be I2 molecule including the Rydberg states or the ion-pair states. Power dependence, pressure dependence, and temporal waveform measurements were also conducted. Moreover, the nascent emission spectrum following the 532 nm was also acquired for comparison. These results shed light on the formation mechanism of these unknown bands.
參考文獻
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