EFFECTS OF TEMPERATURE AND OPTICAL HEATING ON THE OPTICAL-SPECTRA OF METALLOPORPHYRINS IN THE VAPOR-PHASE

The spectral trends associated with static and optical heating are studied for octaethylporphyrins in the gas phase near 600 K. Both the absorption and emission profiles are observed to red shift rapidly with increasing temperature. The 0-0 origin in the absorption spectrum of the Q bands all have a very diffuse character that is well described by a Lorentzian profile with a FWHM of about 20 nm. This linewidth cannot be accounted by collisional or population lifetime broadening. The impact of optical heating in the emission spectra is found to be comparable to that of static heating. The addition of 0.7 eV of excess energy results in a measured temperature rise in octaethylporphyrins of 70 K. The relevance of these results to ultrafast studies in the condensed phase, including heme proteins, is also discussed. © 1995 American Institute of Physics.