COVARIANCE MAPPING AND TRIPLE COINCIDENCE TECHNIQUES APPLIED TO MULTIELECTRON DISSOCIATIVE IONIZATION

Single versus multiphoton multiple ionization of diatomic and triatomi c molecules is discussed. The former experiments use synchrotron radia tion, while the latter ones require pico- or femtosecond laser pulses focused to an intensity exceeding 10(14) W/cm(2). A method of improvin g covariance maps by decorrelating laser fluctuations is presented. Re moval of false coincidences in triple coincidence experiments is exten ded 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 St ark-shift excitation. It is expected that this excitation is accompani ed by emission of vacuum ultraviolet radiation that differs from high harmonic generation.