# Electronic Structures of Chlorophyll a Investigated by Nitrogen K‑Edge X‑ray Absorption Spectroscopy under a Radiation-Induced Effect

## TL;DR

This paper studies the electronic structure of chlorophyll a using X-ray spectroscopy and finds that radiation affects the molecule's structure.

## Contribution

The study reveals how radiation-induced effects alter the electronic structure of chlorophyll a through changes in the phytol chain.

## Key findings

- C=N π* peaks in chlorophyll a show split profiles detectable by X-ray absorption spectroscopy.
- Radiation-induced effects cause progressive changes in the intensity of C=N π* peaks due to phytol chain cleavage.
- Quantum chemical calculations confirm the structural changes affecting electronic properties.

## Abstract

The electronic structures
of high-purity solid chlorophyll a were investigated
using nitrogen K-edge X-ray absorption
spectroscopy. The CN π* peaks of the chlorins exhibited
characteristic split profiles, which changed progressively with successive
scans owing to radiation-induced effects. Inner-shell quantum chemical
calculations for structural models of chlorophyll a with different phytol chain lengths assigned the electronic structures
of the CN π* peaks and confirmed that the intensity
changes of the CN π* peaks are caused by cleaving the
phytol chain. The influence of the vibration of the phytol chain to
the CN π* peaks of the chlorins was also discussed.