Statistical vibrational autodetachment and radiative cooling rates of para-benzoquinone.
Statistical vibrational autodetachment and radiative cooling rates of para-benzoquinone.
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对苯醌的统计振动自脱离和辐射冷却速率。
DOI：
10.1039/d2cp00490a
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Stockett MH
中科院分区：
文献类型：
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作者：
Stockett MH
我们报告测量的统计振动自动脱离（VAD，也称为电子发射）和辐射冷却率孤立的对苯醌（PBQ，C6 H4 O2）自由基阴离子使用低温静电离子储存环设施ECOREE。使用主方程模拟与速率系数使用统计详细平衡理论计算的结果进行解释。VAD速率通过测量中性pBQ的时间依赖性产率来确定，所述中性pBQ的时间依赖性产率是由于来自在电子附着离子源中形成的阴离子的高度激发的系综的自发电子发射。在临界时间τc = 11.00（5）ms后，与辐射冷却的竞争淬灭VAD速率。再现VAD产率的主方程模拟提供了1100（20）K的离子初始有效振动温度的估计，并提供了对阴离子形成情况的洞察。第二次测量pBQ−储存0.5 s的辐射冷却速率是使用2Au <$2B2g和2B 2u <$2B2g跃迁的时间依赖性光剥离作用光谱实现的。的速率，其中热带的贡献褪色的行动频谱是量化的非负矩阵因式分解。发现这与从模拟中提取的平均振动能量相当，1/e寿命分别为0.16（3）s和0.1602（7）s。天体化学的影响进行了讨论。
We report measurements of the statistical vibrational autodetachment (VAD, also called thermionic emission) and radiative cooling rates of isolated para-benzoquinone (pBQ, C6H4O2) radical anions using the cryogenic electrostatic ion storage ring facility DESIREE. The results are interpreted using master equation simulations with rate coefficients calculated using statistical detailed balance theory. The VAD rate is determined by measuring the time-dependent yield of neutral pBQ due to spontaneous electron emission from a highly-excited ensemble of anions formed in an electron-attachment ion source. Competition with radiative cooling quenches the VAD rate after a critical time of τc = 11.00(5) ms. Master equation simulations which reproduce the VAD yield provide an estimate of the initial effective vibrational temperature of the ions of 1100(20) K, and provide insight into the anion formation scenario. A second measurement of the radiative cooling rate of pBQ− stored for up to 0.5 s was achieved using time-dependent photodetachment action spectroscopy across the 2Au ← 2B2g and 2B2u ← 2B2g transitions. The rate at which hot-band contributions fade from the action spectrum is quantified by non-negative matrix factorisation. This is found to be commensurate with the average vibrational energy extracted from the simulations, with 1/e lifetimes of 0.16(3) s and 0.1602(7) s, respectively. Implications for astrochemistry are discussed.