Travel Grant to perform Photoionisation Studies on small Reactive Intermediates at the Elettra (Trieste) synchrotron facility

分子自由基是指处于基电子态的电子数目不成对的分子。正因为如此，它们的反应性很强。它们在等离子体、燃烧和地球大气等环境中很重要，因为它们的反应性，它们通常以低浓度存在。然而，它们在控制这些环境中观察到的最终化学产物和主要化学途径方面发挥着重要作用。分子自由基的电离能，将在这项工作中测量，导致确定离子的形成热和中性分子键解离能，可用于环境模型，如等离子体，火焰和地球的大气。以地球大气中离子的产生为例：——太阳进入地球大气的辐射既有连续的（黑体）分布，也有几条离散的线。这种辐射的一部分能量足以直接电离大气中的分子自由基（即非共振）。另一种电离机制涉及产生高激发的中性态（里德伯态），高于第一个离子极限，然后可以电离。详细研究这些非共振和共振过程对于理解地球大气中不同电子和振动状态下离子的产生是重要的。由分子自由基产生的分子离子在等离子体、燃烧和溶液中也很重要，本项目提出的通过电子结构计算支持的光谱方法研究它们有助于了解它们的结构和性质，从而了解它们在这些环境中的行为。综上所述，分子自由基的光电离过程具有重要的基础意义，在许多科学领域都有应用，包括天体物理学、行星科学、地球大气化学、辐射化学、物理学和生物学。这些领域的工作人员需要电离能和电子激发态和低空离子态的信息，以及在宽光谱范围内光吸收和光电离强度（相对和绝对横截面）的测量。这些信息在这些环境的计算机模拟和建模中特别有用。

Molecular radicals are molecules with an unpaired number of electrons in their ground electronic states. Because of this they are highly reactive. They are important in environments such as plasmas, combustion and the earth's atmosphere where because of their reactivity, they are often present in low concentrations. However, they play a major role in controlling the final chemical products and dominant chemical pathways observed in these environments. Ionization energies of molecular radicals, which will be measured in this work, lead to determination of heats of formation of ions and neutral molecule bond dissociation energies which can be used in models of environments such as plasmas, flames and the earth's atmosphere. The production of ions in the earth's atmosphere will be taken as an example:-Radiation from the sun entering the earth's atmosphere consists of a continuous (black-body) distribution as well as several discrete lines. A part of this radiation is sufficiently energetic to ionize molecular radicals in the atmosphere directly (i.e. non-resonantly). Another mechanism of ionisation involves production of a highly excited neutral state (a Rydberg state), above the first ionic limit which can then ionize. Studying these non-resonant and resonant processes in detail is important in terms of understanding the production of ions in different electronic and vibrational states in the earth's atmosphere. Molecular ions produced from molecular radicals are also important in plasmas, combustion and solution, and studying them via spectroscopic means, supported by electronic structure calculations, as proposed in this project helps to understand their structure and properties, and hence behaviour in these environments. In summary, photoionization processes of molecular radicals are of fundamental importance, and find application in a large number of scientific areas, including astrophysics, planetary science, the chemistry of the earth's atmosphere, radiation chemistry, physics and biology. Workers in these fields require ionisation energies and information on electronic excited neutral states and low-lying ionic states, as well as measures of intensities for photoabsorption and photoionization ( relative and absolute cross-sections) over a wide spectral range. This information is particularly useful in computer simulations and modelling of these environments.