Partial photoionisation cross sections of NH₃ are calculated for processes involving transitions from the ground state to ²A₁ and ²E excited electronic states of the neutral target and residual ion respectively for a wide range of wavelengths using the R-matrix method. Some near threshold structures are resolved. A comparative study is reported for the lone pair 3a ₁ electrons with the isoelectronic system, H₂O [Modak and Antony 2020 J. Phys. B: At. Mol. Opt. Phys. 53 045202]. We observe that the lone pair of NH₃ is loosely bound compared to H₂O. A local rise in cross section data for ²A₁ (3a ₁) electronic state due to autoionisation is also observed from higher excited states. This was earlier predicted by Brion etal [Brion etal 1977 J. Elect. Spectrosc. Rel. Phenom. 12 323]. This is the first report which confirms predissociation due to the dissociative photoionisation of ²E state. A major aim of this study is to resolve Rydberg transitions above the ionisation threshold and quantify them for photoionisation rate coefficients. A recent study by Saraswathya etal [Saraswathya etal 2010 Spectrosc. Lett. 43 290] is the only reported data for few of these Rydberg transitions. These transitions are usually absent in experiments due to the difficulty in resolving narrow energy range. In this investigation, we observed Rydberg transitions above the first ionisation threshold of NH₃. An autoionisation peak is also identified in the background of Rydberg transitions.

使用R-矩阵方法，针对涉及从中性目标的基态到残留离子的² A ₁和² E激发电子态和残留离子的跃迁，分别计算了NH _3的部分光电离横截面。解决了一些接近阈值的结构。据报道，利用等电子系统H ₂ O对孤对3 a ₁电子进行了比较研究[Modak and Antony 2020 J. Phys。B：在。大声笑 选择。物理 53 045202]。我们观察到，与H ₂相比，孤对的NH ₃是松散结合的 O.还从更高的激发态中观察到由于自电离引起的² A ₁（3 a ₁）电子态的横截面数据局部升高。Brion等人[Brion等人， 1977 J.Elect。光谱。相对 hen 12 323]。这是第一个证实由于² E状态的离解光电离而导致的预离解的报告。这项研究的主要目的是解决超过电离阈值的里德伯格跃迁，并量化它们的光电离速率系数。Saraswathya等人的最新研究[Saraswathya等人2010 Spectrosc。来吧 [43 290]是这些里德伯格（Rydberg）过渡中很少几个的唯一报告数据。由于难以解决狭窄的能量范围，因此在实验中通常不存在这些转变。在这项研究中，我们观察到Rydberg跃迁高于NH ₃的第一个电离阈值。在Rydberg转变的背景下也发现了一个自电离峰。