The Nonthermal Rotational Distribution of H3+
The Nonthermal Rotational Distribution of H3+
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H3 的非热旋转分布
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
Erik Epp
中科院分区：
文献类型：
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作者：
T. Oka;Erik Epp
虽然H在等边三角形平衡结构中是非极性的，但由于离心畸变导致的对称性破坏会导致小的偶极矩，从而导致旋转跃迁。自发辐射的时间是在几个星期的顺序为低旋转水平，并在星际空间的碰撞间隔。此外，还有亚稳态转动能级，如J = K = 3，严格禁止自发辐射。一个非常非热旋转分布的产生。我们提出了一个模型计算模拟热化的H。由于H在星际空间中的寿命比自发辐射时间和碰撞间隔长几个数量级，因此假设为稳态近似。精确的理论值从头算理论用于自发辐射率。在完全随机选择规则的假设下，使用满足详细平衡原则的近似公式计算了旋转能级之间的碰撞诱导跃迁率。结果表明，在（3，3）亚稳能级上观测到的高布居数的H原子是向银河系中心（M。后藤等）的观测表明，存在非常大的高温（T ≥ 300 K）和低密度[n（H2）≤ 70 cm-3]云。结果表明，其他较高的亚稳水平可以容纳可观察到的H在这样的云和激发温度从所观察到的相对人口（1，0）和（1，1）应提供关键信息的条件下，这样的云。
Although H is nonpolar in the equilateral triangle equilibrium structure, symmetry breakdown due to centrifugal distortion causes a small dipole moment and hence rotational transitions. The spontaneous emission times are on the order of a few weeks for low rotational levels and are comparable to collision intervals in interstellar space. Moreover, there are metastable rotational levels such as J = K = 3, from which spontaneous emissions are rigorously forbidden. A very nonthermal rotational distribution is produced. We present a model calculation simulating the thermalization of H. Since the lifetime of H in interstellar space is orders of magnitude longer than the spontaneous emission time and collision intervals, a steady state approximation is assumed. Accurate theoretical values by ab initio theory are used for spontaneous emission rates. The rates of collision-induced transitions between rotational levels are calculated on the assumption of completely random selection rules using an approximate formula that satisfies the principle of detailed balancing. The results indicate that the observed high population of H in the (3, 3) metastable level toward the Galactic center (M. Goto and coworkers) signifies the presence of very large high-temperature (T ≥ 300 K) and low-density [n(H2) ≤ 70 cm-3] clouds. It is shown that other higher metastable levels may accommodate observable H in such clouds and that the excitation temperature determined from the observed relative populations of (1, 0) and (1, 1) should provide crucial information on the condition of such clouds.