Resonance-enhanced two-laser infrared multiple photon dissociation of gaseous ions

Ions trapped in a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer exhibited enhanced infrared multiple photon dissociation (IRMPD) when irradiated sequentially by two carbon dioxide lasers using a novel IRMPD probe/pump photodissociation scheme. A low-power pulsed (probe) laser tuned to a resonant infrared absorption band promoted trapped ions to vibrationally excited states, but often had insufficient energy to cause photodissociation. Subsequent irradiation of the excited ions with a fixed-frequency, nonresonant, continuous wave (pump) laser induced photofragmentation. Photodissociation spectra were obtained by varying the wavelength of the probe laser. A novel White-type cell which shows great promise for dramatically enhancing the effect of the probe laser has been designed and constructed for use with these experiments. © 1991 American Chemical Society.