PHOTODISSOCIATION OF KR-N+ CLUSTERS

The photodissociation of Krn+ (3≤n≤11) cluster ions is observed for the first time in the 565 to 630 nm wavelength range. Kr3+ has a photodissociation cross section of (8.1 ± 0.8)× 10-17 cm2 at 612 nm, while Kr 4+ and Kr5+ are found to have larger photodissociation cross sections than Kr3+ with a slightly red-shifted spectrum. Only Kr+ is detected as a photofragment of Kr3+, while in the Krn + (4≤n≤7) experiments, both Kr2+ and Kr+ photofragments are seen. As size n increases from 7 to 11, Kr+ disappears and Kr3+ appears. Laser power studies show that all are single photon photodissociation processes. For higher order Krn+ clusters (4≤n≤7) the intensity ratio between the two photodissociation products Kr2+ and Kr+ is dependent on the wavelength of the laser light used in the photodissociation, but independent of the polarization direction of the laser. Translational energy analysis of the photofragments is used to investigate the photodissociation mechanisms. In contrast to the photodissociation of Kr 3+, where two types of Kr+ photofragments with different values of translational energy release are observed, only one type of Kr2+ photofragment, with zero kinetic energy release is found in the Kr4+ photodissociation. These findings are discussed in terms of the dynamics of photodissociation and possible structures of these cluster ions. © 1990 American Institute of Physics.