Eur. Phys. J. D 38, 151-162 (2006)
https://doi.org/10.1140/epjd/e2006-00029-y

Photolysis of NO₂ at multiple wavelengths in the spectral region 200–205 nm

A velocity map imaging study

¹ Department of Molecular and Laser Physics, University of Nijmegen, 6500 GL Nijmegen, The Netherlands
² Institute of Theoretical Chemistry, University of Nijmegen, 6525 ED Nijmegen, The Netherlands
³ Facultad de Ciencias, Dpt. Qumica Fisica, I. F. Quimica, Universidad Compultense, Madrid, Spain
⁴ School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK

Corresponding author: ^a parker@science.ru.nl

Received: 8 August 2005
Published online: 8 February 2006

Abstract

A study of the photodissociation dynamics of NO₂ in the 200–205 nm region using resonance enhanced multiphoton ionization (REMPI) in conjunction with the velocity map imaging technique is presented. We chose this region because it allowed the use of a single laser to photodissociate the NO₂ molecule and probe both the O(¹D₂) fragment using (2+1) REMPI via the 3p'¹P₁ state at 2 ×205.47 nm and the 3p'¹F₃ state at 2 ×203.5 nm, and the O(³P_J) fragments using (2+1) REMPI via the P_J states around 2 ×∼200 nm. Translational energy and angular distributions are extracted from the O(¹D) and O(³P) product images. A growth in the population of highly excited vibrational levels of the NO X(²Π) co-fragment is found as the dissociation wavelength decreases. These are compared with similar trends observed previously for other triatomic O-atom containing molecules. Detailed information on the electronic angular momentum alignment of the ¹D₂ state is obtained from analysis of the polarization sensitivity of the O(¹D) images using the two resonant intermediate states. The angular dependence of the potential energy in the exit channels is examined using long-range quadrupole-dipole and quadrupole-quadrupole interaction terms, from which molecular-frame multipole moments of the total angular momentum of the recoiling O atoms have been calculated. Comparison with the experimentally derived multipole moments is used to help provide insight into the dissociation mechanism.