Covariance mapping and triple coincidence techniques applied to multielectron dissociative ionization

Single versus multiphoton multiple ionization of diatomic and triatomic molecules is discussed. The former experiments use synchrotron radiation, while the latter ones require pico- or femtosecond laser pulses focused to an intensity exceeding 10(14) W/cm(2). A method of improving covariance maps by decorrelating laser fluctuations is presented. Removal of false coincidences in triple coincidence experiments is extended to a varying excitation rate. An explanation of the multielectron dissociative ionization mechanism is sought in terms of bond softening, bond hardening (stabilisation), and ionization enhancement due to Stark-shift excitation. It is expected that this excitation is accompanied by emission of vacuum ultraviolet radiation that differs from high harmonic generation.