Table of Contents
Laser Chemistry
Volume 8, Issue 2-4, Pages 243-257

Transient Isomerisation and Inverse Electronic Relaxation of Infrared Multiple-Photon Excited Pentafluoropyridine

Chemistry Division, Bhabha Atomic Research Centre, Trombay, Bombay 400 085, India

Received 24 August 1987; Accepted 5 October 1987

Copyright © 1988 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Pentafluoropyridine (PFP) undergoes fast structural isomerisation to fulvenes when irradiated with 9R(16) CO2 laser line in the fluence range 0.5–1.5 J/cm2. The unstable fulvenes slowly decay back to PFP in ms time scale. No detectable permanent dissociation of PFP was observed in the above low fluence experiments. However, by using focused CO2 laser beam for the irradiation of PFP, an emission of light in the visible/near-UV was observed. The time evolution of the luminescence reveals three peaks at 390, 460 and 500 nm on a broad background emission of 300–680 nm. These bands are assigned to the fluorescence of PFP via inverse electronic relaxation (IER) and C2 Swan bands. On prolonged irradiation of PFP in focused condition a small extent of permanent dissociation was observed with the major products as C2F4, a sooty yellow deposit and another compound presumed to be Dewar PFP.