Resonance Enhanced Two-Laser Infrared Multiple Photon Dissociation of GaseousIons

摘要

Ions trapped in a Fourier Transform Ion Cyclotron Resonance (FTICR) massspectrometer 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 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 dramatically enhances the effect of the probe laser has been designed and constructed for use with these experiments. Infrared multiple photo dissociation, Infrared spectra of ions, Fourier transform ion cyclotron resonance mass spectrometry, Lasers, Ions, Kinetics, Gas analysis, Collisions, Molecular structure, Energy levels, Probes. (jg)