Thermal decomposition of NCN(3) as a high-temperature NCN radical source: singlet-triplet relaxation and absorption cross section of NCN((3)Σ).
Thermal decomposition of NCN(3) as a high-temperature NCN radical source: singlet-triplet relaxation and absorption cross section of NCN((3)Σ).
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NCN(3)作为高温NCN自由基源的热分解：NCN((3)Σ)的单重态-三重态弛豫和吸收截面
DOI：
10.1021/jp1043046
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
G. Friedrichs
中科院分区：
文献类型：
--
作者：
J. Dammeier;G. Friedrichs
在激波管实验中研究了叠氮化氰（NCN 3）热分解作为高温氰氮（NCN）源的可能性。电子基态NCN（3 <$）自由基已被窄带宽激光吸收在属于振动热的A <$3 <$u（010）−X <$3 <$g−（010）系统的振动3 <$+−3 <$子带的Q1分支的重叠跃迁处检测到，在ν <$= 30383.11 cm−1（329.1302 nm）。在总压为0.2−2.5 bar时直接测量了高温吸收截面σ，log[σ/（cm 2 mol −1）] = 8.9−8.3 × 10−4×T/K（± 25%，750 <T< 2250 K）。在这些高温下，NCN（3 π）的形成受到最初形成的受激NCN（1Δ）自由基的缓慢电子弛豫的限制，而不是NCN 3的热分解。测得的与温度相关的碰撞诱导系间穿越（CIISC）速率常数最好用kCIISC/（cm 3 mol − 1 s −1）=（1.3 ± 0.5）× 1011 exp [−（21 ± 4）kJ/mol/RT]（740 <T< 1260 K）表示。然而，稳定的NCN浓度平台已被观察到，表明NCN 3是一个理想的前体NCN动力学实验后冲击波。
The potential of the thermal decomposition of cyanogen azide (NCN3) as a high-temperature cyanonitrene (NCN) source has been investigated in shock tube experiments. Electronic ground-state NCN(3Σ) radicals have been detected by narrow-bandwidth laser absorption at overlapping transitions belonging to the Q1branch of the vibronic3Σ+−3Π subband of the vibrationally hot Ã3Πu(010)−X̃3Σg−(010) system at ν̃ = 30383.11 cm−1(329.1302 nm). High-temperature absorption cross sections σ have been directly measured at total pressures of 0.2−2.5 bar, log[σ/(cm2mol−1)] = 8.9−8.3 × 10−4×T/K (±25%, 750 <T< 2250 K). At these high temperatures, NCN(3Σ) formation is limited by a slow electronic relaxation of the initially formed excited NCN(1Δ) radical rather than thermal decomposition of NCN3. Measured temperature-dependent collision-induced intersystem crossing (CIISC) rate constants are best represented bykCIISC/(cm3mol−1s−1) = (1.3 ± 0.5) × 1011exp[−(21 ± 4) kJ/mol/RT] (740 <T< 1260 K). Nevertheless, stable NCN concentration plateaus have been observed, showing that NCN3is an ideal precursor for NCN kinetic experiments behind shock waves.