摘要
对草酰氯分子的多键解离方式进行了理论和实验的研究。计算表明，草酰氯的第一电子激发态增强了C－C键而削弱了C－Cl键，解离出Cl原子和ClCOCO自由基。在351nm光解实验中观察到中间物ClCOCO的红外发光，该中间物很容易进一步热解为ClCO和CO，势垒仅为0．4eV。第二电子激发态形成C－C较强的反键轨道，造成C－C键的解离而产生ClCO，在248nm光解实验中，产生了振转激发的终产物CO。以瞬态模型分析了CO的振转内能分配，与实验值吻合。
Multi-bonding dissociation of oxalyl chloride (ClCO)2 in its first electronically excited state (A1Au) and second excited state (B1Au) were studied respectively by ab initio calculations and time-resolved infrared emission spectroscopy. The first excited state of oxalyl chloride (A1Au) was prepared by 351nm laser excitation. The C-C bond is strengthened While the C-Cl bond is weakened, indicating a cleavage of C-Cl bond. The emission band of ClCOCO radical centered at 1850cm-1 was observed. Consequently, ClCOCO (X2A1) radical dissociates into ClCO and CO, overcoming a small barrier of 0.4eV. The second excited state of oxalyl chloride (B1Au), which was prepared by 248nm laser excitation, preferrs to break the C-C bond. The generated two ClCO radicals further dissociate into final products of Cl and CO. The CO emission band was observed in the infrared spectra. A vibrational temperature of 3500K and a rotational temperature of 2000K of the nascent CO were obtained by the simulation of the infrared emission spectra.
基金
国家自然科学基金
