甲醇交流放电产物的光谱研究

利用浓度调制光谱技术测量甲醇交流放电分解产物的发射光谱，在300～700 nm之间主要观测到激发态CO分子的B 1Σ+—A1Π Angstrōm跃迁带、激发态CH分子430 nm附近的A 2Δ—X 2Π跃迁带系和390 nm附近的B 2Σ-—X 2Π跃迁带系以及CHO(329.82 nm)，CH₂O(369.8 nm)，CH₃O(347.8 nm)，H（巴末耳线系）的发射谱线。通过光谱强度分析得到，CO激发态B 1Σ+的振动温度达1 638 K，CH激发态A 2Δ的振动和转动温度分别为4 200和1 100 K。改变放电电压和样品气压，测量CO，CH和H的发射光谱强度的变化关系，发现增加放电电压或减少样品气压，CO（B 1Σ+）和H(656 nm) 的发射光谱强度比CH(A 2Δ)发射光谱强度增加得快，从而进一步讨论了甲醇交流放电解离通道和产氢机制。

Study on Decomposition Products of Methanol in AC Discharge by Spectroscopy

The intermediate decomposition products of methanol (CH₃OH) in an AC discharge were diagnosticated via concentration modulation spectroscopy. Several main vibrational bands of CO Angstrōm B1Σ＋-A 1Π system, CH A 2Δ-X　2Π system at 430 nm and B 2Σ－-X 2Π at 390 nm, as well as CHO(329.82 nm), CH₂O(369.8 nm), CH₃O(347.8 nm) and Balmer series spectra of H atom were identified in the region between 300 and 670 nm. Furthermore, the dependences of the emission spectral intensities of the intermediate decomposition products on the discharge voltage and parent gas pressure were investigated in detail. The experiments indicated that the relative population ratio of CO(B 1Σ＋) and H increases with increasing discharge voltage more quickly than that of CH(A 2Δ). Several possible reaction passages were given and discussed. Additionally, the vibrational and rotational temperatures of CH(A 2Δ) were determined to be about 4 200 and 1 100 K respectively, and the vibrational temperatures of CO(B 1Σ+) were determined to be about 2 500 K by analyzing the intensity distribution using LIFEBASE computer program. The decomposition mechanism of methanol in the discharge plasma was discussed as well.