---
author:
- 'Alan N. Heays'
- Ruud Visser
- Roland Gredel
- Wim Ubachs
- 'Brenton R. Lewis'
- 'Stephen T. Gibson'
- 'Ewine F. van Dishoeck'
bibliography:
- 'anhrefs.bib'
date: '**Draft –** '
title: Isotope selective photodissociation of by the interstellar radiation field and cosmic rays
---

[Photodissociation of and occurs in interstellar clouds, circumstellar envelopes, protoplanetary discs, and other environments due to ultraviolet radiation originating from stellar sources and the presence of cosmic rays. This source of N atoms initiates the formation of more complex N-bearing species and may influence their isotopic composition.]{} [To study the photodissociation rates of by ultraviolet continuum radiation and both isotopologues in a field of cosmic ray induced photons. To determine the effect of these on the isotopic composition of more complex molecules.]{} [High-resolution theoretical photodissociation cross sections of N$_2$ are used from an accurate and comprehensive quantum-mechanical model of the molecule based on laboratory experiments, as presented for Li et al. 2013. A similarly high-resolution spectrum of H$_2$ emission following interactions with cosmic rays has been constructed. The spectroscopic data are used to calculate photodissociation rates which are then input into isotopically differentiated chemical models, describing an interstellar cloud and a 