Vibrational Spectroscopy and Photodissociation Properties of Ions As Determined by Two-Laser Photodissociation Techniques.

Article abstract of DOI:10.1021/j100242a036

Iodobenzene, bromobenzene, and m-iodotoluene cations trapped in an ion cyclotron resonance (ICR) mass spectrometer undergo an enhanced visible photodissociation process in the presence of infrared irradiation.The infrared wavelength dependence in the 9.7-10.7-μm region for this effect exhibits features wich relate to the infrared spectroscopy of these ions.The variation in extent of the infrared enhancement with visible wavelength is interpreted as reflecting two different mechanisms: at short wavelengths the enhancement is attributed to changes invisible-absorption cross section with increasing internal energy and gives a useful means of observing such effects, while at long wavelengths the enhancement is attributed to a perturbation of the two-photon dissociation kinetics.The photodissociation rates of several other ions were shown not to undergo an enhancement effect when irradiated with the infrared laser.