To investigate the chemical effect on the muon capture process through a muon transfer reaction from a muonic hydrogen atom, the formation rate of muonic carbon atoms is measured for benzene and cyclohexane molecules in liquid samples. The muon transfer rate to carbon atoms of the benzene molecule is higher than that to the carbon atoms of the cyclohexane molecule. Such a deviation has never been observed among those molecules for gas samples. This may be because the transfers occur from the excited states of muonic hydrogen atoms in the liquid system, whereas in the gas system, all the transfers occur from the 1 s (ground) state of muon hydrogen atoms. The muonic hydrogen atoms in the excited states have a larger radius than those in the 1 s state and are therefore considered to be affected by the steric hindrance of the molecular structure. This indicates that the excited states of muonic hydrogen atoms contribute significantly to the chemical effects on the muon transfer reaction.

中文翻译：

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苯和环己烷样品中通过μ子转移反应对形成μ原子的化学作用

为了研究通过μ氢原子的μ子转移反应对μ子捕获过程的化学作用，测量了液体样品中苯和环己烷分子的μ碳原子的形成速率。对苯分子碳原子的μ子转移速率高于对环己烷分子碳原子的μ子转移速率。从未在气体样品的那些分子中观察到这种偏差。这可能是因为转移是从液态系统中的μ氢原子的激发态发生的，而在气体系统中，所有转移都是从μs氢原子的1 s（基态）发生的。处于激发态的离子氢原子的半径比处于1 s态的氢原子的半径大，因此被认为受分子结构的空间位阻的影响。